Nearly every cell in the body uses calcium to communicate with neighboring cells, and researchers can follow these exchanges by tracking changes in calcium. Previous work by the Ahrens Lab and its collaborators had established ways to image calcium signals across the entire brain of a transparent larval zebrafish, including methods for equipping neurons with sensors that light up when calcium changes. Those approaches supplied glimpses of activity within one major system, but they did not provide a simultaneous account of communication across the fish’s brain, cardiovascular system, digestive system, muscles and other organs.

WHOLISTIC, an abbreviation for WHole Organism Live Imaging System for recording Tissue and IntraCellular activity, was designed to address that gap. Its central technical challenge was to introduce a calcium sensor into almost every cell in the fish’s body, then detect the resulting activity despite differences among tissues and cell types. The researchers used high-speed volumetric fluorescence imaging to record signals throughout the body at once. They also developed computational methods that tracked signals as the fish moved, aligned them across the recording and identified different cell types from their activity patterns. Because many cells lacked specific labels, the team subsequently used whole-body expansion microscopy to enlarge the tissue and reveal fine structural details that helped confirm the identities of cells captured by WHOLISTIC.

The method allows researchers to examine individual cells while retaining information about the organism-wide context in which their activity occurs. Virginie Ruetten, a postdoctoral researcher in Misha Ahrens’s lab who performed the work as a joint graduate student with Ahrens and Maneesh Sahani, described the technique as a bridge between two fundamental scales of biology: the cell and the organism. This combination makes it possible to observe cellular responses at scale while also recording the behavior and physiological state of the same animal. It also allows investigators to examine networks that are distributed among organs rather than contained in a single location, potentially revealing relationships that would be difficult to identify by studying one tissue in isolation.

Initial applications showed widespread correlations in cellular activity among the brain, muscles and organs, indicating broad coupling between these systems. Many cell types from different organs also displayed characteristic temporal dynamics. Those patterns allowed the computational analysis to identify cell types even when the cells had no specific fluorescent labeling, adding another way to characterize the cellular organization captured in the recordings. Ahrens said the simultaneous view permits scientists to examine which elements are connected, when their activity changes together and which relationships may otherwise be overlooked. The observations do not, by themselves, establish that every detected correlation is causal, but they show that coordinated signaling can be measured across the same vertebrate at cellular resolution and in real time.

One application addressed the physiological response to insufficient oxygen. WHOLISTIC revealed body-wide mechanisms involved in survival under low-oxygen conditions and showed that the brainstem controls the redirection of blood flow from the gut toward the brain and muscles. This finding brought the nervous and cardiovascular systems into the same cellular recording, making it possible to observe a coordinated response across distant organs as the animal faced a common physiological challenge. The study further illustrates the practical value of a whole-body approach: information that would otherwise be divided among separate specialties can be analyzed concurrently in one living animal.

A second series of observations was made during prolonged motor quiescence, a state that may be associated with sleep. The researchers detected traveling activity oscillations along the spinal cord and brain that originated in ependymal cells, the cells lining the ventricles that contain cerebrospinal fluid. Because the recordings captured both these cells and the spatial propagation of their activity, the findings suggest that ependymal cells may participate in sleep-related processes. The evidence does not establish that the traveling oscillations generate sleep, nor does it resolve the full causal chain connecting cellular activity, neural propagation and behavioral state. It does, however, identify a candidate cellular source for a coordinated body-wide pattern and provide a means of testing that role in future experiments.

The whole-body recordings also identified cell types that respond to cold, including chondrocytes, the main cellular components of cartilage. Ketamine produced a separate pattern in which the meninges — the cells and connective tissue surrounding the brain — responded along with neurons. These observations demonstrate that an imaging strategy focused on the entire animal can detect activity in tissues that might be missed when a study concentrates only on the brain or one peripheral organ. They also show that WHOLISTIC can be applied to questions involving physiological challenges, behavioral states and responses to a pharmacological agent within the same experimental framework.

The team is now adapting WHOLISTIC to Danionella, a fish that remains transparent throughout its life. The days-old larval zebrafish used in the reported experiments can be observed under a microscope, but the researchers note that Danionella can display more complex behaviors, potentially making it useful for investigating how a vertebrate brain generates behavior. They also plan to share the fish with the scientific community and make the computational methods open source. The microscope used for the technique is commonly found in biology laboratories, which the researchers hope will support broader adoption. The work is an early step toward simultaneous observation of cellular communication across an animal; it does not provide a complete account of human physiology or demonstrate that the same circuits operate in mammals.

Subject of Research: Whole-organism calcium imaging of cellular communication in larval zebrafish

Article Title: A ‘WHOLISTIC’ view of cellular communication across an entire animal

Article References: A ‘WHOLISTIC’ view of cellular communication across an entire animal. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: WHOLISTIC, larval zebrafish, calcium imaging, cellular communication, whole-body circuits, fluorescence microscopy, behavior, physiology, cell identification, neuroscience, view, cellular

The paper, titled ‘The first brain at the centre: An enteric reframing of the nervous system,’ was authored by Dr Tim Hibberd, Hayley Rhodes and Professor Nick Spencer of Flinders University. It was published as a commentary, meaning it presents an interpretive argument synthesized from existing evidence rather than the results of a single new experiment. Even so, its implications reach into the heart of evolutionary neuroscience, because it suggests that the energy-hungry business of digestion, not cognition, may have been the original driving force behind the emergence of nervous tissue in early animals.

At the center of the argument is the enteric nervous system, the vast web of neurons embedded in the walls of the gastrointestinal tract. Often described as the body’s ‘second brain,’ this network contains hundreds of millions of neurons in humans, a number that rivals or exceeds the neuronal population of the spinal cord. Crucially, the enteric nervous system can operate without direct input from the brain or spinal cord. It senses the chemical and mechanical conditions of the gut lining, processes that information locally, and coordinates complex patterns of muscle contraction, secretion and blood flow that make digestion possible. Isolated segments of intestine continue to generate coordinated peristaltic activity in laboratory conditions, a striking demonstration of just how autonomous this system is.

Dr Hibberd, from Flinders’ College of Medicine and Public Health, argues that this autonomy is precisely why the enteric nervous system deserves to be reconsidered as the body’s original neural architecture. ‘We are proposing a different way of looking at the nervous system,’ he says. ‘The enteric nervous system in the gut can sense its environment, process information and coordinate complex responses. In many ways, it functions like a brain in its own right.’ By that logic, he and his colleagues contend, it may be more accurate to think of the gut’s neural network not as a second brain but as the first one.

The evolutionary reasoning behind this claim rests on a simple biological imperative. For any organism, the overriding priority is securing energy: capturing nutrients, breaking them down and distributing them to tissues. Early multicellular animals faced this challenge without the benefit of centralized nervous systems. A diffuse network of neurons arranged around the digestive apparatus would have provided an immediate survival advantage, allowing a primitive gut to detect food, respond to it and coordinate the movements needed to move it through the body. Only later, as animals grew larger, more mobile and more behaviorally complex, would centralized brains have become useful, and even then, the Flinders researchers argue, the brain’s fundamental role remained to support the gut’s mission of energy acquisition.

This perspective aligns with features of modern nervous system diversity. Many animals with simple body plans, including certain cnidarians and other basal lineages, possess nerve nets with little or no centralization, organized largely around the oral and digestive regions. In more complex animals, the gut tube retains its own complete nervous system regardless of how elaborate the brain has become. The persistence of this independent enteric circuitry across such a wide range of species, the researchers suggest, hints at its ancient origins. Rather than being a derived or secondary feature, the gut’s nervous system may preserve the architecture of the earliest nervous systems that ever evolved.

Senior author Professor Nick Spencer, from Flinders Health and Medical Research Institute, says the theory helps explain a puzzle that has long interested physiologists: why the gut remains so influential in directing functions throughout the body, long after brains capable of vision, memory and movement appeared. ‘The gut is constantly gathering information and communicating with other organs,’ says Professor Spencer. ‘It plays a major role in regulating digestion, metabolism and other functions essential for survival. These fundamental processes may have helped drive the evolution of the nervous system.’ The gut, in this framing, is not a passive organ awaiting instructions but an active sensing and signaling hub whose outputs ripple through hormones, immune signaling and neural pathways to shape appetite, metabolism and even mood.

The reframing also speaks to a growing body of research on the gut-brain axis, the bidirectional communication network linking the gastrointestinal tract with the central nervous system. The vagus nerve provides a direct neural highway between gut and brain, while gut-derived hormones modulate hunger, satiety and glucose regulation. Clinical observations have reinforced the significance of this axis: alterations in gut function are increasingly documented in conditions as varied as Parkinson’s disease, obesity and diabetes. In Parkinson’s disease, for example, aggregates of the protein alpha-synuclein have been detected in the enteric nervous system, prompting ongoing debate about whether pathological processes may begin in the gut before reaching the brain. A theoretical framework that treats the gut’s nervous system as primary, rather than peripheral, could reshape how such connections are investigated.

The Flinders team is candid that their proposal is unlikely to change medical practice overnight. As an opinion piece, it functions as a challenge to the field, an invitation to reinterpret existing evidence through a different lens rather than a definitive proof of gut-first neural evolution. But the authors argue that the conceptual stakes are high, because the assumptions scientists bring to anatomy shape the questions they ask about disease. ‘The way we think about the body shapes the way we investigate disease,’ says Dr Hibberd. ‘If we begin to view the gut as a central player in nervous system function, it may open up new avenues for research.’ Those avenues could include exploring the enteric nervous system as a therapeutic target for metabolic and neurodegenerative disorders, or re-examining the evolutionary record of early animals with fresh attention to the neural tissue surrounding the digestive tract.

Whatever the ultimate verdict of the scientific community, the paper injects new energy into one of evolution’s oldest questions. If the Flinders researchers are right, the human brain, with all its capacity for language, art and abstraction, is best understood not as the founding organ of the nervous system but as a brilliant late addition, recruited in service of an older, quieter intelligence coiled within the gut. The idea invites scientists and the public alike to reconsider where the story of the nervous system truly began: not in the skull, but in the ancient, energy-driven demands of the gut that every animal, from the simplest worm to the human being, still carries at its core.

Subject of Research: Evolutionary origins of the enteric nervous system and the gut-first hypothesis of brain evolution

Article Title: What evolved first – our brain or gut?

Article References: What evolved first – our brain or gut?. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: enteric nervous system, evolution, gut-brain axis, neuroscience, digestion, Flinders University, Journal of Physiology, brain evolution, Parkinson's disease, metabolism, second brain, physiology

The challenge the team faced was a familiar one in animal research: how to measure posture continuously without attaching markers, sensors, or harnesses to the animal. Marker-based systems require extensive animal preparation and can interfere with natural behavior, while manual observation is too imprecise for rigorous analysis. Their solution was a custom pipeline built around a stereo camera that records the animal from two viewpoints simultaneously, feeding the footage into a deep learning system trained to detect fifteen anatomical landmarks on the sheep’s body. The result is a markerless record of how the animal’s body position shapes its internal pressure landscape.

The technical core of the system is a two-stage detection process. First, a custom object detector locates the sheep in each frame, isolating the animal from its surroundings. Second, a landmark detection network identifies fifteen anatomical points on the sheep’s body, from the head and neck to the limbs and hooves. The team trained this network on footage from six sheep, giving it enough appearance variability to handle the low inter-individual variation within the species. The pipeline was designed to work on animals it has never seen before, without requiring additional labeling or retraining.

Once the landmarks are detected, the system reconstructs the sheep’s three-dimensional body position from the two camera viewpoints. This reconstruction is then refined using a smoothing process that enforces temporal continuity, ensuring that the record of the animal’s movement is stable and reliable. The team evaluated this refinement against the raw detections, confirming that the smoothed record is more consistent than the unprocessed data. The result is a stable, three-dimensional record of how the animal moves through its environment.

The final stage of the pipeline classifies the sheep’s body position into predefined categories, such as standing, lying, and other postures. This classification allows the team to segment video sequences into meaningful intervals, facilitating retrospective analysis and simplifying future research. The team trained this classifier on footage from six sheep, giving it enough variability to handle the low inter-individual variation within the species. The result is a system that can automatically segment hours of footage into meaningful intervals.

The team paired this posture pipeline with eight simultaneously recorded pressure signals, selected because they were critical to investigations of cerebrospinal fluid dynamics. The pressure channels are treated generically throughout the system, allowing the number and type of measurements to change without intrinsically tying the pipeline to a specific set of signals. The team synchronized the pressure recordings with the stereo footage, creating a complete record of how the animal’s body position shapes its internal pressure landscape. The result is a system that can correlate posture with physiology in a living animal.

The team evaluated the pipeline on footage from six sheep, confirming that it works on animals it has never seen before without requiring additional labeling or retraining. The annotated landmarks encompass frames from six sheep, providing sufficient appearance variability to support generalization given the low inter-individual variation within the species. The pipeline was designed to be modular, supporting flexible integration of new detection networks and pressure signals. The result is a system that can adapt to future advances in animal research.

The team acknowledged that the pipeline has limitations. The system records eight pressure signals that were selected because they were critical to investigations of cerebrospinal fluid dynamics, but the pipeline is not intrinsically tied to this specific set of measurements. The team also noted that the pipeline was evaluated on a limited number of animals, and that future work should expand the evaluation to more subjects. The result is a system that can adapt to future advances in animal research.

The team concluded that their markerless pipeline offers a new way to correlate posture with physiology in a living animal. By pairing a simple stereo camera with eight simultaneously recorded pressure signals, the system can interpret how body position shapes the internal pressure landscape of a living sheep. The pipeline was designed to be modular, supporting flexible integration of future advances in detection networks and pressure signals. The result is a system that can adapt to future advances in animal research.

Subject of Research: Physiology

Article Title: Automated 3D sheep posture estimation and telemetric pressure synchronization via a markerless computer vision pipeline

Article References: Roncoroni, M., Podgoršak, A., Kaufmann, A., Flürenbrock, F., Trimmel, N. E., Oertel, M. F., Zeilinger, M., Weisskopf, M., & Schmid Daners, M. (2026). Automated 3D sheep posture estimation and telemetric pressure synchronization via a markerless computer vision pipeline. Frontiers in Veterinary Science, 13, Article 1933870. https://doi.org/10.3389/fvets.2026.1933870

Image Credits: AI Generated

DOI: 10.3389/fvets.2026.1933870

Keywords: sheep, stereo camera, posture, pressure signals, cerebrospinal fluid, markerless, animal model, physiology, Automated, estimation, telemetric, pressure

The framework, developed by Torsak Tippairote of the University of South Africa and HP Medical Center in Bangkok and Pruettithada Hoonkaew of Mahachai Hospital in Samut Sakhon, Thailand, builds on a century of stress physiology, from Walter Cannon’s homeostasis and Hans Selye’s general adaptation syndrome to modern models of allostasis and allostatic load. What those classical frameworks describe well is the mobilization of energetic resources during challenge. What they describe less well, the authors argue, is why coordinated stress responses sometimes resolve cleanly and sometimes become persistent and maladaptive. Their answer draws on network physiology, an emerging field that treats the body not as a collection of independent organs but as a dynamically interacting web of physiological systems whose coordination patterns can be measured and modeled.

Bioenergetic impedance is defined as the time-dependent constraint on energetic throughput and recovery that arises when energetic pressure exceeds available biological capacity. The terminology is deliberately borrowed from electrical engineering, but the authors are careful to note that the analogy is heuristic rather than literal: there is no claim of electrical equivalence or a universal impedance metric. Instead, the framework organizes a relational sequence of concepts. Energetic demand generates pressure. Conductance governs how much throughput that pressure can drive. Buffering capacity temporarily accommodates mismatches between demand and throughput. Reserve represents latent capacity that can be recruited during challenge, and recovery capacity specifically supports the resolution, repair, replenishment, and adaptive remodeling that follow it. Resistance, delay, congestion, and buffering burden may contribute to or manifest impedance, while compensatory rerouting may represent the body’s attempt to work around a constrained pathway.

Crucially, the construct is scale dependent rather than a single global quantity. The organizing principle—energetic pressure exceeding available throughput and recovery capacity—can apply at the level of cells, tissues, organs, or whole physiological networks, but the mechanisms and measurements differ at each scale. The authors also draw a sharp boundary around what bioenergetic impedance is not: it is not synonymous with mitochondrial dysfunction, inflammation, lactate accumulation, or any single biomarker. Those processes become relevant only when they contribute to, reflect, or sustain a demonstrable mismatch between demand, throughput, and recovery. The framework, in other words, organizes relationships among established biological processes rather than renaming them.

At the cellular level, the framework anchors itself in three mechanistic scenarios. The first is substrate congestion and redox backpressure: when carbon skeletons and reducing equivalents such as NADH enter metabolism faster than mitochondria can oxidize them, intermediates accumulate and oxidative flux becomes constrained. Cells can respond by increasing respiratory throughput, restricting substrate entry, buffering the excess, or rerouting carbon flow. Chronic nutrient excess and the insulin resistance that follows may illustrate one such adaptive restriction of substrate entry, though the authors emphasize this is compatible with the framework rather than direct proof of it. The second scenario is adaptive metabolic rerouting, exemplified by lactate production, which regenerates NAD+ and sustains glycolytic flux when oxidative metabolism cannot fully accommodate incoming substrate. Rerouting is not inherently pathological; its significance depends on whether it accompanies a sustained demand-throughput mismatch and a failure to restore oxidative flexibility. The third is mitochondrial stress signaling, in which mitochondrial remodeling, integrated stress responses, reactive oxygen species signaling, tricarboxylic acid cycle metabolites, and even the release of mitochondrial nucleic acids translate local energetic strain into transcriptional, inflammatory, and immune signals that can propagate beyond the cell.

That propagation is where the framework makes its most distinctive move. Because physiological systems are coupled, a local bioenergetic constraint can alter signaling, resource distribution, or functional demand elsewhere in the body—through metabolites, cytokines, mitokines such as GDF15 and FGF21, autonomic and neuroendocrine signaling, vascular responses, or nutrient redistribution. The authors distinguish local impedance, which occurs when pressure within a cell or tissue exceeds its capacity, from network-level impedance, a higher-order state in which distributed constraints and compensatory responses reorganize the interactions among physiological systems and sustain a compensatory configuration. Importantly, this relationship is bidirectional: whole-organism neuroendocrine, immune, and behavioral responses can alter the demand imposed on local energetic machinery, just as cellular constraints can reshape those same networks. One illustrative example comes from recent work on metabolic dysfunction-associated steatohepatitis, in which GDF15-mediated brainstem signaling suppressed hepatic inflammation independently of weight loss—a systemic stress communication compatible with the proposed architecture, though not direct evidence of network lock-in.

The framework’s central prediction concerns reversibility. In adaptive impedance cycling, a challenge that transiently exceeds available capacity produces impedance, followed by recovery that restores or adaptively recalibrates flexible cross-system organization—and, when adaptive remodeling expands capacity, potentially produces hormetic expansion of reserve. Consistent with hormetic conditioning, the framework predicts that adaptive remodeling should yield smaller impedance excursions, faster resolution, and preserved or expanded reserve during comparable subsequent challenges. In maladaptive trajectories, by contrast, the initiating pressure persists or the time and resources required for recovery are insufficient before the next challenge arrives. Incomplete recovery leaves residual constraint and reduced reserve, so each subsequent challenge begins from an incompletely resolved state and encounters greater impedance. With repetition, compensatory responses become persistent, network reconfigurability declines, and resources remain preferentially allocated toward continued defense rather than restoration. The authors call this persistent state impedance lock-in, a descriptive term that does not imply a formally demonstrated dynamical attractor.

From a network physiology perspective, the distinguishing signature is not simply increased or decreased coupling between organ systems. Increased coupling may reflect effective coordination or compensatory recruitment; persistent coupling may indicate unresolved demand; reduced coupling may reflect appropriate release of coordination after an exposure resolves, or, during exhaustion, loss of physiological integration. Lock-in should instead be identified by persistent or stereotyped reconfiguration together with impaired recovery, residual constraint or hysteresis, reduced network flexibility, altered task-dependent centrality, and incomplete restoration of functional reserve. The key question is always whether network interactions remain appropriate to physiological demand, permit impedance to resolve, and restore or expand subsequent adaptive capacity.

The framework also generates concrete, testable predictions. First, reducing persistent energetic pressure—from inflammation, hypoxia, sleep disruption, environmental exposures, excessive substrate load, pain, or sustained psychosocial stress—should improve recovery without necessarily increasing nutrient or substrate supply, distinguishing the impedance model from a simple substrate-deficiency account. Second, improving a limiting determinant of conductance, buffering, or recovery capacity—such as oxygen delivery, vascular perfusion, oxidative capacity, or metabolically active tissue—should permit greater adaptive throughput. Third, impedance and recovery should be tested sequentially under standardized challenge: under comparable imposed demand, greater independently measured demand-capacity mismatch should predict slower recovery, greater residual constraint, altered network reconfiguration, and reduced tolerance of a subsequent challenge. A standardized exercise protocol could serve as exactly such a test, with adaptive trajectories showing rapid recovery and restored challenge tolerance and lock-in trajectories showing delayed, incomplete recovery and declining tolerance.

The authors are candid about the framework’s current status. Bioenergetic impedance remains a proposed systems-level construct rather than an established measurable quantity, and evidence for its component mechanisms establishes biological plausibility without independently validating the higher-order construct. They also propose Exposure-Related Malnutrition as a hypothesis-generating candidate phenotype—a state in which sustained metabolic and adaptive demand may exceed available bioenergetic capacity, with resources preferentially allocated toward vital functions while growth, maintenance, repair, and recovery become relatively under-supported—but they stress that independent empirical validation remains limited and that the phenotype requires an operational case definition. The framework’s ultimate utility will depend on whether prospectively defined demand-capacity constraints predict recovery dynamics, network reconfiguration, and subsequent adaptive capacity, and whether they provide explanatory value beyond established measures such as cardiorespiratory fitness, allostatic load indices, and frailty scores. If they do, the implications could be profound: a physiology in which the decisive variable for health is not how much stress we face, but whether the network can complete the respond-adapt-recover cycle before the next challenge arrives.

Subject of Research: A network physiology framework proposing bioenergetic impedance as a systems-level construct linking cellular energetic constraints to stress adaptation, maladaptation, and recovery

Article Title: Bioenergetic impedance: a network physiology framework for stress adaptation, maladaptation, and recovery

Article References: Tippairote, T., & Hoonkaew, P. (2026). Bioenergetic impedance: a network physiology framework for stress adaptation, maladaptation, and recovery. Frontiers in Network Physiology, 6, Article 1967461. https://doi.org/10.3389/fnetp.2026.1967461

Image Credits: AI Generated

DOI: 10.3389/fnetp.2026.1967461

Keywords: bioenergetic impedance, network physiology, stress adaptation, recovery dynamics, mitochondria, resilience, allostasis, metabolic health, Bioenergetic, impedance, network, physiology

The choice of the specific parameters measured in this study reflects both practical constraints and the priorities of space medicine. Body weight, core body temperature, blood pressure, heart rate, and peripheral oxygen saturation are inexpensive, quick, and reliable to obtain in a confined habitat without specialized equipment, making them feasible for repeated measurement by crew members themselves. Each parameter also serves as a proxy for a distinct physiological system. Body weight integrates fluid balance, energy intake, and expenditure, and shifts in weight during confinement can signal changes in dietary habits, hydration, or activity levels. Blood pressure and heart rate reflect cardiovascular regulation and, indirectly, autonomic nervous system tone, which is sensitive to stress, sleep quality, and physical activity. Core body temperature relates to thermoregulation and circadian rhythmicity, both of which can be disrupted when natural light cycles and environmental variability are removed. Peripheral oxygen saturation, while generally stable in healthy individuals at sea level, provides a safety margin check that can detect respiratory or environmental problems. Together, these five measures form a minimal but informative panel for monitoring crew health in resource-limited settings.

The pronounced inter-individual variability observed, particularly for body weight and cardiovascular measures, deserves careful attention because it mirrors one of the most consistent findings across analog and spaceflight literature. Individual responses to identical environmental stressors can diverge substantially, influenced by baseline fitness, habitual diet, sleep chronotype, stress coping styles, and prior experience with confined or expeditionary settings. In the Mars500 experiment, for example, crew members showed markedly different patterns of sleep-wake disruption and activity over the 520-day simulated mission, and similar heterogeneity has been documented in Antarctic overwintering personnel. This variability has practical consequences: group-level averages can mask clinically meaningful changes in individual crew members, which argues for personalized monitoring approaches in which each individual serves as their own control. It also complicates the design of analog studies, since small cohorts drawn from a variable population may not represent the range of responses expected in larger, more diverse astronaut corps.

The methodological decision to rely on descriptive statistics rather than inferential testing reflects a common and often underappreciated challenge in analog research. With 40 participants measured at three time points, the dataset is respectable by the standards of analog missions, which frequently involve crews of four to six individuals. Even so, the authors found that several variables deviated from normal distributions, as assessed with Q-Q plots, which undermines the assumptions underlying parametric tests such as repeated-measures analysis of variance. Non-normal distributions of physiological parameters in small samples can arise from genuine biological heterogeneity, from measurement variability, or from the bounded nature of some measures such as oxygen saturation, which clusters near its physiological ceiling. When distributional assumptions fail, inferential tests lose their interpretability, and presenting medians, ranges, and distribution shapes becomes more honest than reporting p-values that may be unstable or misleading. This approach also guards against overinterpreting random fluctuation as meaningful adaptation, a pitfall that has affected some smaller analog studies.

The measurement schedule itself, with assessments on Days 1, 7, and 14, represents a compromise between scientific resolution and operational feasibility. Weekly sampling can capture broad trends and identify whether parameters drift over the mission, but it cannot resolve day-to-day fluctuations that may carry their own information. Heart rate and blood pressure, for instance, are influenced by acute factors such as sleep quality, caffeine intake, exercise timing, and even the stress of being measured, and single daily readings may not distinguish between transient variation and genuine directional change. The authors’ call for higher-frequency monitoring in future studies aligns with a broader trend in space health research toward continuous or near-continuous ambulatory monitoring using wearable sensors. Such devices can capture heart rate variability, activity levels, and sleep patterns around the clock, providing a far richer picture of autonomic adaptation than episodic spot checks. However, wearables introduce their own challenges in confined habitats, including sensor drift, skin irritation, data management, and the psychological effect of constant observation on crew behavior.

The LunAres Research Station itself is worth situating within the broader landscape of analog facilities. Located in Piła, Poland, it operates as an isolated habitat in which crews live and work without access to the external environment for the duration of a mission, simulating key characteristics of what researchers term ICE environments: isolated, confined, and extreme. Unlike facilities that simulate specific planetary surfaces, such as HI-SEAS on Hawaiian volcanic terrain or stations designed around Martian regolith scenarios, LunAres emphasizes the human factors dimension of isolation, with modular living quarters, laboratory space, a gym, and a kitchen arranged around a central research area. This design makes it particularly suitable for studies of behavioral health, crew dynamics, and physiological monitoring under confinement, complementing facilities whose primary value lies in geological or operational realism. The diversity of analog platforms is itself an asset, since different facilities isolate different subsets of the stressors experienced in spaceflight, allowing researchers to attribute effects more precisely.

It is important to recognize what this study deliberately does not model. Microgravity, space radiation, and the specific hazards of launch and landing are absent by definition in a terrestrial habitat, and the authors are explicit that their aim was not to replicate spaceflight physiology. This transparency matters because analog findings are sometimes overextended in popular reporting, with confinement effects conflated with the cardiovascular deconditioning or bone loss caused by weightlessness. What analogs like LunAres isolate is the psychological and behavioral component of spaceflight: the loss of environmental variety, the enforced proximity to a small group, the structured routines, and the separation from family and normal social life. These stressors are genuinely relevant to long-duration missions, and their physiological correlates, such as altered sleep, changed activity patterns, and stress-mediated cardiovascular adjustments, can be studied without the enormous cost and rarity of orbital research. The finding that short-term confinement alone did not perturb basic physiological parameters suggests that, for healthy adults, the psychological stress of a two-week isolation is within the adaptive capacity of normal homeostatic mechanisms.

The emphasis on standardized measurement protocols in the authors’ conclusions points to a persistent weakness in the analog literature. Because analog studies are conducted by many independent groups with different instruments, timing conventions, and definitions of baseline, results are difficult to compare or pool. Blood pressure measured after rest versus after activity, body temperature measured orally versus tympanically, and weight measured at different times of day relative to meals can all yield systematically different values. Establishing community standards for measurement timing, posture, instrumentation, and data reporting would allow individual studies to contribute to a cumulative evidence base rather than existing as isolated snapshots. The authors’ observation that routine parameters are often interpreted without adequate consideration of confounders such as hydration status, circadian phase, and recent physical activity is a pointed reminder that even simple measurements require careful protocol design to be interpretable.

The prospective observational design, in which measurements were planned before the mission and collected at fixed time points, strengthens the study relative to retrospective analyses of mission records, though it remains observational in the strict sense. Without a control group experiencing the same schedule outside confinement, the study cannot attribute any observed change specifically to isolation, and indeed the absence of temporal trends means there is little to attribute. This limitation is inherent to analog research, where the practical and ethical difficulty of isolating a matched control group for two weeks is considerable. Some studies address this by comparing mission data with pre-mission baseline periods or with crew members’ habitual routines, and future LunAres studies could incorporate such baseline extensions to sharpen inference.

Finally, the study’s framing of physiological stability as a finding in its own right, rather than as a failure to detect effects, is a useful corrective to publication norms that favor dramatic results. Demonstrating that a well-controlled two-week confinement does not destabilize basic cardiovascular, thermal, and metabolic markers in healthy adults provides a reassuring data point for short-duration mission planning and establishes a baseline against which longer missions can be compared. The authors’ recommendation to add psychological markers alongside physiological ones acknowledges that the most consequential effects of isolation may be behavioral rather than vital-sign-based, and that integrated monitoring of mood, cognition, sleep, and interpersonal dynamics will be essential as mission durations extend toward the months and years required for lunar surface operations and eventual journeys to Mars.

Subject of Research: Physiological monitoring of healthy adults during a 14-day isolated analog space mission

Article Title: Analytical comparison of physiological parameters in participants during an analog space mission

Article References: Kijak, K., Lubkowska, A., Skomro, P., Ardan, R., Budkowska, M., Gronwald, B., Gronwald, H., Stachowska, E., Kijak, K., Orzechowski, L., Mintus, A., & Lietz-Kijak, D. (2026). Analytical comparison of physiological parameters in participants during an analog space mission. Frontiers in Space Technologies, 7, Article 1752453. https://doi.org/10.3389/frspt.2026.1752453

Image Credits: AI Generated

DOI: 10.3389/frspt.2026.1752453

Keywords: space analog mission, isolation, LunAres Research Station, physiology, blood pressure, heart rate, body temperature, oxygen saturation, space medicine, confinement, inter-individual variability, Analytical

The review, led by Professor Art Woods, synthesizes decades of experimental work on how two high-elevation phenomena affect insect biology: hypoxia, the condition of low oxygen availability, and hypobaria, the condition of reduced atmospheric pressure. Both change dramatically with altitude. At the summits of mountains, the air holds substantially less oxygen per unit volume than at sea level, and the barometric pressure that drives gas exchange is correspondingly lower. For large-bodied vertebrates such as humans, these changes are familiar enough, producing the breathlessness that hikers experience at altitude. For insects, however, the consequences are shaped by a respiratory architecture that is utterly different from our own lungs, and by body plans and life cycles that amplify the challenges of thin air in unexpected ways.

Insects breathe through a tracheal system, an elaborate network of external openings called spiracles connected to internal tubes that ramify through every tissue of the body. Oxygen moves through this system primarily by diffusion, supplemented in many species by active ventilation of the larger air sacs. This design is remarkably efficient at small body sizes and at low altitudes, allowing insects to sustain metabolic rates that can exceed those of similarly sized vertebrates. But the tracheal system has an inherent vulnerability: because oxygen delivery depends on diffusion along concentration gradients and on pressure-driven flow, it is sensitive to the oxygen content and density of the outside air. As elevation increases and ambient oxygen partial pressure falls, the gradient driving oxygen into the tracheae weakens, and the system must work harder to supply the same amount of oxygen to demanding tissues such as flight muscles.

The review found that flying insects are among the groups most likely to struggle at higher elevations. Flight is the most metabolically expensive form of locomotion in the animal kingdom, and insect flight muscles consume oxygen at extraordinary rates. In thinner air, two problems compound each other. First, reduced air density means that wings generate less lift with each stroke, forcing insects to flap faster, tilt their stroke planes, or otherwise expend more mechanical energy simply to stay airborne. Second, the reduced oxygen partial pressure limits how quickly the tracheal system can replenish the oxygen consumed by those hard-working muscles. The combined effect is a double penalty: the demand for oxygen rises precisely as the supply becomes harder to maintain. Experiments cited in the review indicate that for some species, flight performance begins to degrade at elevations that are, by human standards, only moderately high.

Juvenile insects face their own set of altitude-related hurdles. The researchers found that species with active larval stages, such as caterpillars that feed voraciously and grow rapidly, are particularly constrained. Growth is an oxygen-hungry process, and actively feeding larvae already operate close to the limits of their respiratory systems even at low elevation. Their tracheal systems, embedded in tissues that expand rapidly during growth spurts, must deliver oxygen fast enough to support the synthesis of new body mass. At higher elevations, where ambient oxygen is scarcer, this balance can tip toward oxygen limitation, slowing growth, extending development times, and potentially reducing survival. Because larval performance ultimately determines adult body size and fecundity, these constraints could ripple through entire populations attempting to establish themselves at newly suitable higher elevations.

Aquatic insects add yet another dimension to the problem. Species such as dragonflies, mayflies, and many midges spend their juvenile stages in water, where oxygen is already far less abundant and diffuses far more slowly than in air. Water holds only a fraction of the oxygen found in an equivalent volume of air, and cold, still waters at high elevation can be particularly oxygen-poor. The review notes that aquatic larvae are therefore already living close to their oxygen limits, and the conditions at higher elevations can exacerbate this stress further. For these species, the uphill shift in range must be accomplished not only by flying adults crossing thin air but by aquatic juveniles tolerating waters that may offer even less oxygen than the streams and ponds they occupy today.

Water loss emerged as a third barrier in the review. Higher elevations frequently combine strong winds, intense solar radiation, and low absolute humidity, all of which accelerate evaporative water loss. For small animals with large surface-area-to-volume ratios, desiccation is a constant threat. Insects can reduce water loss by closing their spiracles, but every closure also restricts oxygen uptake, creating a direct trade-off between conserving water and breathing adequately. In thin, dry mountain air, this trade-off becomes sharper: the insect must open its spiracles more often or for longer to obtain sufficient oxygen, losing precious moisture with each exchange. The physiological catch-22 could make high-elevation environments punishing for species that might otherwise find the temperatures there hospitable.

Professor Woods emphasized how counterintuitive these findings are. Because insects obtain oxygen through a network of external openings and internal tubes distributed throughout their bodies, it is tempting to assume they have no trouble acquiring all the oxygen they need. Humans can visit moderately high elevations with only minor discomfort, so surely insects, with their seemingly direct air supply, would manage easily. But the experimental data tell a different story. The oxygen demands of active insects, especially growing juveniles and flying adults, are high enough that their respiratory systems struggle to deliver oxygen fast enough at even modestly higher elevations. In other words, the very efficiency of the tracheal design at low altitude does not guarantee performance when the atmospheric conditions change, and the margin of safety that insects enjoy at sea level can vanish surprisingly quickly as they climb.

The broader implications extend well beyond insect physiology. Insects are keystone contributors to ecosystem functioning, performing essential services that include pollination, decomposition, nutrient cycling, and serving as food for countless birds, bats, and other animals. If warming temperatures push insects toward elevations they cannot physiologically occupy, the result may not be a neat upward migration but a squeeze, with populations trapped between intolerable heat below and unbreathable thin air above. Disrupted pollination is among the most immediate concerns, since both wild plants and crops depend on insect pollinators whose ranges may fail to track the flowering schedules of the plants they serve. Such mismatches could degrade crop production and destabilize the ecological interactions that underpin mountain biodiversity, from alpine meadows to cloud forests.

The researchers call for more targeted research on high-elevation species to better understand the physiological constraints that govern upslope range shifts, and they argue that the knowledge gained will be vital for informing conservation strategies. Identifying which species can breathe, fly, grow, and reproduce at altitude, and which cannot, would allow conservation planners to anticipate which insect populations are most vulnerable as the climate warms, and to prioritize habitats, corridors, and refugia accordingly. The study serves as a reminder that climate change vulnerability is not simply a matter of temperature tolerance. The atmosphere itself, its oxygen content, its pressure, and its drying power, changes with elevation in ways that can quietly undermine the escape routes that range-shifting species are expected to use. For insects, the uphill path away from a warming world may be steeper than anyone realized.

Subject of Research: Physiological constraints of high-elevation oxygen and pressure limits on insect range shifts under climate change

Article Title: Insects could face an uphill battle adapting to climate change

Article References: Insects could face an uphill battle adapting to climate change. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: insects, climate change, hypoxia, hypobaria, elevation, range shifts, tracheal system, pollination, physiology, Functional Ecology, conservation, aquatic larvae

The study, led by researchers including Edgar Cristancho-Mejía and Walter Schmidt, recruited healthy, non-smoking adults who had lived at their respective altitudes for at least two years. Participants came from six locations spanning 970 to 2600 meters, including regions around Bogotá in the Central Eastern Andes and the lower Western Andes near Tuluá and Cali. Crucially, none of the participants were endurance athletes, eliminating a major confounding factor that has plagued earlier comparisons between highland populations and sea-level dwellers. The cohort included 133 men and 148 women, with ancestry distributions reflecting the regional population mix of African, European, and Native American heritage.

Measuring hemoglobin mass directly is technically demanding, and the team used the optimized carbon monoxide rebreathing method, widely regarded as the gold standard. Participants inhaled a precisely calculated dose of carbon monoxide over two minutes, and the researchers tracked how much of it bound to hemoglobin in the blood, allowing an accurate calculation of total hemoglobin mass. From this, together with venous hemoglobin concentration and hematocrit, the team derived red cell volume, plasma volume, and total blood volume. Blood samples drawn from a cubital vein provided hemoglobin concentration, hematocrit, and oxygen saturation values for each participant.

The results revealed a clear and unexpected divergence in thresholds. Hemoglobin mass rose significantly only in residents living at 2180 meters or higher, with the effect becoming firmly established at 2600 meters. Plasma volume, by contrast, was already significantly reduced at 1730 meters—roughly 450 meters lower than the erythropoietic threshold. Between the lowest and highest study locations, hemoglobin concentration increased by about 1.0 grams per deciliter in men and 1.3 grams per deciliter in women, while hematocrit rose by roughly 3.2 to 3.7 percentage points. Relative to lean body mass, hemoglobin mass was 5.8 percent higher in men and 8.9 percent higher in women at 2600 meters compared with 970 meters, while plasma volume per kilogram of lean mass fell by about 6 percent in both sexes.

The physiological logic behind these two thresholds traces back to the shape of the oxygen dissociation curve. This sigmoid curve allows arterial blood to remain nearly fully saturated with oxygen up to altitudes of roughly 2000 meters, meaning the kidneys—the primary sensors of oxygen availability—detect little reason to stimulate red cell production. Below that ceiling, the flat upper portion of the curve buffers the modest drop in ambient oxygen pressure. Once saturation begins to fall more steeply, however, the kidney responds by releasing erythropoietin, triggering the bone marrow to expand hemoglobin mass. Plasma volume regulation operates on a different logic entirely: it responds to the overall oxygen-carrying deficit rather than to a specific saturation threshold, and it does so within days rather than weeks.

When the researchers combined their data with earlier measurements taken at 420 and 3800 meters in Bolivia using the same methodology, a striking pattern emerged. Hemoglobin mass increased slowly and modestly up to about 2600 meters, then climbed sharply at higher elevations, reaching values 27 percent above near-sea-level levels at 3800 meters. Notably, within the moderate-altitude range of the current study, there was no significant relationship between hemoglobin mass and oxygen saturation—suggesting that up to roughly 2600 meters, altitude exerts only a gentle influence on erythropoiesis. Above that point, the diminishing oxygen supply becomes the dominant driver, most likely registered by oxygen-sensing mechanisms in the kidneys.

To quantify how much each component contributed to the observed rise in hemoglobin concentration, the team performed multiple regression analyses. The calculations showed that every 100-gram increase in hemoglobin mass raised concentration by 1.59 grams per deciliter, while every liter of plasma volume loss raised it by 3.07 grams per deciliter. Applying these coefficients to the altitude-related changes, the researchers found that of the 1.2 grams per deciliter elevation in hemoglobin concentration at 2600 meters, approximately 0.56 grams per deciliter was attributable to increased hemoglobin mass and 0.61 grams per deciliter to reduced plasma volume—a near-perfect split. When the team applied an alternative correction for the Fåhraeus effect, which accounts for differences between central and peripheral hematocrit, the plasma volume contribution grew even larger.

The findings carry immediate clinical weight. Hemoglobin concentration is one of the most commonly ordered diagnostic measurements in medicine, and anemia thresholds are already adjusted for altitude. Yet the hemoconcentration caused by plasma volume contraction at moderate elevations has never been factored into those thresholds. If a substantial fraction of the altitude-related rise in hemoglobin reflects a shrunken liquid blood volume rather than genuinely enhanced oxygen-carrying capacity, then current anemia criteria may misclassify residents of towns like Bogotá at 2600 meters. The study also resonates with recent work on high-altitude populations worldwide: data from Sherpa communities in the Himalayas suggest their lower hemoglobin concentrations compared with Andean highlanders stem largely from larger plasma volumes rather than smaller hemoglobin masses, underscoring that the ratio of red cells to plasma, not red cell count alone, defines the blood’s oxygen transport profile.

The authors acknowledge limitations. Sample sizes at individual altitudes were modest, and the high interindividual variability in hemoglobin mass—driven largely by differences in lean body mass—means the altitude effect, though statistically robust, is just one of several factors shaping any person’s blood profile. Ambient temperature may also play a role, since the lowland study sites were considerably warmer, and heat acclimatization is known to expand plasma volume. Plasma volume itself was calculated indirectly rather than measured directly, and the Fåhraeus correction introduces some uncertainty, though the researchers showed that an altitude-adjusted correction strengthened rather than weakened their conclusions. Nevertheless, the study provides the first systematic evidence that the blood’s response to moderate altitude unfolds in two distinct stages: plasma contracts first, at around 1730 meters, and the erythropoietic machinery follows at roughly 2180 meters. For the roughly 5 percent of humanity living above 1500 meters, that distinction may soon matter at the doctor’s office as much as on the mountain.

Subject of Research: Altitude thresholds for hemoglobin mass and plasma volume regulation and their effects on hemoglobin concentration in Andean residents

Article Title: Altitude thresholds for hemoglobin and plasma volume regulation in adult residents of different altitudes and their impact on hemoglobin concentration

Article References: Cristancho‐Mejía, E., Trompetero‐Gonzalez, A. C., Benavides‐Pinzón, W. F., & Schmidt, W. F.-J. (2026). Altitude thresholds for hemoglobin and plasma volume regulation in adult residents of different altitudes and their impact on hemoglobin concentration. Physiological Reports, 14(19), Article e71108. https://doi.org/10.14814/phy2.71108

Image Credits: AI Generated

DOI: 10.14814/phy2.71108

Keywords: hemoglobin mass, plasma volume, altitude, hypoxia, erythropoiesis, Andes, Colombia, anemia thresholds, oxygen saturation, blood volume, CO rebreathing, physiology

The study, conducted by a Brazilian research team using exclusively public data, evaluated all 42 athletes who competed across three modalities: track sprinting, swimming, and weightlifting. These athletes brought impressive credentials, including Olympic and world championship medals, yet their historical personal bests sat on average about 6 percent below the existing world records at the time of competition. That gap matters because the typical difference between two sequential world records in these sports is usually less than 1 percent. In other words, the field entered the event far from record-breaking territory, and the pharmacological protocols on offer would have needed to produce extraordinary gains to close it.

They did not. Across 60 analyzed performances by enhanced athletes, only a single world record fell, set by a male swimmer in the 50-meter freestyle. Crucially, that swim was aided by a polyurethane suit of the kind banned in World Aquatics competition, a piece of equipment notorious for its buoyancy and hydrodynamic advantages rather than any biological effect. The same 50-meter freestyle record had already been broken under full World Anti-Doping Agency compliance just weeks earlier, in March 2026, without such a suit, which the authors note suggests the promised gains from the drug protocols were not as effective as advertised. In track and field, not a single athlete surpassed a personal best, and performances drifted further from world-record pace after the Games than before them.

The physiological rationale behind the event’s protocols was not baseless. Anabolic-androgenic steroids and growth hormone reliably stimulate muscle protein synthesis, producing chronic gains in lean mass and maximal strength, while recombinant erythropoietin elevates hemoglobin mass and oxygen-carrying capacity, improving maximal aerobic capacity in laboratory settings. Historical precedent appeared to support the enterprise: the state-sponsored doping program of the German Democratic Republic between the 1970s and 1980s yielded roughly 150 Olympic medals, and high-profile scandals from BALCO to the Russian scheme in Sochi reinforced the perception that pharmacology delivers results worth the risk. Yet an umbrella review cited by the researchers found insufficient evidence directly linking these substances to improved on-field competitive performance, a distinction between laboratory adaptation and real-world outcome that proved decisive in Las Vegas.

According to the publicly available clinical trial registration associated with the Games, the protocol involved 25 weeks of various testosterone esters and derivatives, with most participants using testosterone, more than half using stimulants, and a minority using erythropoietin or additional anabolic steroids. The authors caution that actual doses and exact substances were never disclosed, leaving open the possibility that administration fell within clinically recommended ranges insufficient for meaningful performance enhancement. They also note that gains in muscle mass and force do not always transfer to sport-specific outcomes, where hydrodynamics, aerodynamics, technique, and neuromuscular timing impose demands that hypertrophy alone cannot satisfy.

On the individual level, the picture was mixed but underwhelming. Nineteen new personal bests were achieved out of 60 enhanced-athlete performances, all in swimming or weightlifting, representing a genuine if modest accomplishment given that most competitors were past their athletic prime. Athletes who set new personal bests improved by roughly 3 percent on average, while the remaining 41 performances declined by about 5.6 percent relative to prior marks. Weightlifting showed the greatest variability, with three athletes achieving new bests while eight regressed, some by double-digit margins. Swimming was the only modality in which the overall gap to world records remained comparable to the historical pre-Games gap, a result the authors suggest may have been confounded by the permitted use of banned polyurethane suits rather than the drug protocols themselves.

Age emerged as a more plausible explanation for the few successes than pharmacology. Athletes who set new personal bests were, on average, closer in age to the point at which they had previously peaked, roughly five years removed from their best performances compared with seven years for those who regressed. Peak performance in sprinting, swimming, and weightlifting generally occurs in the early to mid-twenties, and the researchers argue that a smaller age gap, combined with the enhancement protocol, likely drove the improved marks rather than any dramatic drug effect. If the protocols had been as powerful as claimed, they contend, performances should have exceeded expectations across the board, which was not the case for the majority of competitors.

The event’s third core promise, that enhancement could offset age-related decline and even support longevity, fared worst of all. Using a linear mixed-effects model with athlete identity as a random intercept, the team examined the relationship between the number of years elapsed since each athlete’s personal best and the percentage change in performance at the Games. The slope was negative, meaning performance tended to worsen as time since peak increased, and while the association did not reach statistical significance at the conventional threshold, the authors note that this direction of effect directly contradicts the claim that drug protocols could counteract aging. Physical capacities such as maximal strength, power, and aerobic function are well documented to decline after the third decade of life, and nothing in the Las Vegas data suggested pharmacology had reversed that trajectory.

Perhaps the most pointed observation concerns the handful of athletes who competed without any enhancement at all. Four athletes self-declared as non-enhanced, and their six performances were on average closer to their personal bests, about 1 percent below, than the enhanced athletes’ aggregate 3 percent deficit. One non-enhanced swimmer achieved two new personal bests, and a non-enhanced sprinter came closest among track competitors to surpassing his own record. The sample is far too small for definitive conclusions, and self-declared status was never independently verified, but the pattern reinforces a conclusion the authors emphasize throughout: elite athletic performance is multifactorial, shaped by training quality, injury history, technique, and psychology, and not determined by pharmacology alone. The study has clear limitations, including the absence of dose information, no age-matched control group, and the inherent constraints of retrospective observational analysis of publicly available data. Even so, the collective evidence indicates that the Enhanced Games failed to deliver on all three of its central promises, generating one suit-assisted world record, a minority of new personal bests concentrated in swimmers and lifters, and no detectable attenuation of age-related decline. The human body, it turns out, may indeed be an incomplete project, but the pharmaceutical toolkit on display in Las Vegas was not the shortcut its promoters promised.

Subject of Research: Performance outcomes of doping-permitted competition at the inaugural Enhanced Games

Article Title: Enhanced but not superior: Performance outcomes from the inaugural enhanced games

Article References: Azevedo, R. A., Coutinho, L. F., Gonçalves, M. C., Oliveira, H. A., Gonçalves, G. J., Campos, M., Roschel, H., & Gualano, B. (2026). Enhanced but not superior: Performance outcomes from the inaugural enhanced games. Physiological Reports, 14(19), Article e71123. https://doi.org/10.14814/phy2.71123

Image Credits: AI Generated

DOI: 10.14814/phy2.71123

Keywords: Enhanced Games, performance-enhancing drugs, anabolic steroids, erythropoietin, world records, athletic performance, aging, anti-doping, physiology, swimming, weightlifting, track and field

The first of the two studies set out to answer a question that has long interested developmental scientists: what actually happens inside a baby when a joyful exchange with a parent unfolds? To find out, the researchers measured changes in the heart rates of nearly 1,000 four-month-old infants as they engaged in positive interactions with their mothers. Electrodes were attached to the babies’ chests and stomachs, while trained observers watched the mother-infant pairs and recorded, moment by moment, whether each member of the pair displayed positive, neutral, or negative engagement. This combination of continuous physiological recording and fine-grained behavioral observation allowed the team to link what was happening between the mother and baby with what was happening inside the baby’s body.

The physiological measure at the center of the study was respiratory sinus arrhythmia, a form of heart-rate variability that is coupled with breathing. Scientists understand this variability to be a biological indicator tied to emotion regulation and to a person’s adaptability to different environments. In adults and in children, higher heart-rate variability in this range is generally associated with a more flexible capacity to respond to social and emotional demands. By calculating this measure from the infants’ heart-rate data, the researchers could ask whether moments of shared positivity were accompanied by shifts in the biological systems that support emotional self-regulation.

The answer was striking. The researchers found increases in the babies’ heart-rate variability precisely when the infants and their mothers were positively engaged at the same time. Crucially, the same physiological changes did not appear when only the baby was smiling, or when only the mother was showing positive emotion. Both partners had to be on the same positive wavelength for the effect to emerge. Daniel Messinger, a professor in the Department of Psychology at the University of Miami College of Arts and Sciences and a senior author on the paper, put it plainly: “They both have to be positive. When they’re both positive, particularly for longer periods of time, you see this increase in the baby’s heart rate.”

That mutual requirement may be the study’s most important insight. It suggests that emotional development is not simply a matter of a happy baby or an affectionate parent acting alone. Instead, the physiological states associated with emotion regulation appear to be recruited during genuine two-way exchanges, in which both the caregiver and the infant are sharing positive affect simultaneously. “Play is not just fun and games. It’s influencing the baby’s physiology,” said Messinger, who is also a professor of pediatrics. “There’s something about positive sociality that’s associated with this internal baby state. The baby’s physiology is linked to what’s going on in the interaction.” In other words, the interaction itself, not the mood of either partner in isolation, is what seems to matter.

The scale and design of the study lend weight to its conclusions. The research was part of a national study on drug exposure conducted at four sites across the country, including Miami, and involved several universities. When the team analyzed the heart-rate data, they controlled for prenatal drug exposure and social adversity, helping to ensure that the observed link between shared positivity and heart-rate variability was not simply an artifact of those factors. Among the members of the research team was Samantha G. Mitsven, a University of Miami alumna who worked on the study while completing her Ph.D. in developmental and child psychology. With nearly 1,000 infants contributing data, the study represents one of the larger physiological investigations of early mother-infant interaction.

The second study, also published in Philosophical Transactions of the Royal Society B, approached infant smiling from a different angle by asking how babies and adults influence each other’s smiling over time. The researchers observed 58 infants at two ages, 4 months and 8 months, while the babies interacted with their mothers, their fathers, and a stranger. This design allowed the team to compare smiling dynamics across different relationship partners within the same infants, revealing patterns that would be invisible in studies focused on mothers alone.

The results showed a clear division of labor in early smiling exchanges. Adults initiated and reciprocated smiling interactions at higher rates than infants did, and seeing an adult smile significantly increased the rate at which babies began smiling themselves. Babies, on the other hand, were more likely to be the ones who ended shared smiling moments, a pattern the researchers interpret as a possible sign that infants are learning to moderate their own excitement. The team also found developmental change: at 8 months, the babies were both more likely to start a smiling interaction on their own and more likely to reciprocate an adult’s smile compared with when they were 4 months old. “That suggests that the dyad becomes more dynamically responsive to one another at older ages,” said Messinger, who was a first author on the paper along with Eliala Alice Salvadori, who conducted the research for her dissertation at the University of Amsterdam, and Cristina Colonnesi, an associate professor at the University of Amsterdam. Another first author, Alan B. Cobo-Lewis, completed his postdoctoral fellowship and undergraduate studies at the University of Miami and is now an associate professor at the University of Maine.

Perhaps the most socially revealing finding came from the comparison across partners. At both ages, babies were most likely to return their mother’s smiles, compared with smiling interactions involving their fathers or an unknown adult. The adults who were strangers actually initiated and sustained smiles more often than the mothers did, yet the infants responded preferentially to their mothers. “This was, importantly, the first paper that involved not only moms and dads, but also strangers,” Messinger noted. “The strangers initiate and sustain smiles more than moms, but infants are more likely to smile back at the mom. So, the relationship really counts there.” The finding underscores that infant smiling is not a reflexive response to any friendly face, but a selectively tuned behavior shaped by the specific relationship between the baby and the person in front of them.

Together, the two studies sketch a picture of early emotional development as a genuinely interactive process. The heart-rate study shows that mutual positive engagement, sustained over time, is associated with increases in a physiological indicator linked to emotion regulation, while the smiling study shows that these exchanges become more fluid, reciprocal, and relationship-specific as infants grow from 4 to 8 months of age. For parents, the practical message is encouraging rather than demanding: ordinary moments of shared laughter and smiling are not idle pleasures but may be part of the biological work of early development. For scientists, the results open a window onto how social experience and physiology intertwine in the first months of life, suggesting that the foundations of emotional well-being are built not in solitude, but in the back-and-forth of a shared smile.

Subject of Research: The role of shared positive caregiver-infant interactions in infants' physiological and emotional development

Article Title: Shared smiles may shape infants’ emotional development

Article References: Shared smiles may shape infants’ emotional development. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: infant development, emotion regulation, heart-rate variability, respiratory sinus arrhythmia, mother-infant interaction, smiling, caregivers, developmental psychology, physiology, social interaction, University of Miami, Philosophical Transactions of the Royal Society B

Standard organoid culture media typically include a basal formulation such as DMEM/F12 supplemented with factors that promote neural differentiation, including N2 and B27 supplements, and often retinoic acid at later stages to encourage photoreceptor maturation. Variations among laboratories in the choice of basal medium, the concentration of supplements, the presence or absence of serum components, and the timing of factor additions have long been recognized as sources of heterogeneity, but the systematic consequences of these choices for downstream applications have been less thoroughly characterized. The finding that media alter both adeno-associated virus transduction and retinal ganglion cell survival suggests that seemingly minor formulation differences can propagate into functional outcomes that matter enormously for translational work.

Adeno-associated virus vectors are the leading platform for retinal gene therapy, with approved products demonstrating that subretinal or intravitreal delivery can produce durable clinical benefit in inherited retinal degenerations. The success of AAV-mediated gene transfer depends on a cascade of events: vector particles must reach the target cells, bind to cell surface receptors, undergo endocytosis, traffic through the cytoplasm, enter the nucleus, uncoat, and convert their single-stranded genome into a transcriptionally competent double-stranded form. Each step can be influenced by the physiological state of the target cell, including membrane composition, endosomal trafficking dynamics, proteasome activity, and the expression of factors that second-strand synthesis. If culture media shift cells into states that favor or hinder any of these steps, then organoid-based assessments of vector tropism and potency will yield results that are artifacts of the culture condition rather than faithful predictions of clinical behavior.

This consideration is particularly acute because organoids are increasingly used as preclinical screening platforms for vector engineering. Researchers seeking capsids with improved photoreceptor tropism, or with the ability to penetrate the inner limiting membrane after intravitreal injection, frequently validate their designs in retinal organoids before advancing to animal studies. A capsid that appears highly efficient in organoids maintained in one medium might underperform in organoids maintained in another, not because the capsid has changed but because the cellular context has. Standardizing media composition, or at minimum reporting it comprehensively and testing key findings across multiple formulations, would strengthen the predictive value of such screens and reduce the risk of pursuing vector designs whose apparent advantages do not survive a change of culture conditions.

The effects on retinal ganglion cell survival are equally consequential. Retinal ganglion cells are the projection neurons of the visual system, conveying visual information from the retina to the brain through the optic nerve, and their degeneration underlies glaucoma and other optic neuropathies. In organoid culture, ganglion cells are notoriously fragile; they are among the first cell types generated, they reside in the innermost layer of the tissue, and they depend on trophic support that is difficult to reproduce in a dish. Their progressive loss during long-term organoid culture is a well-documented limitation, and it complicates any effort to model ganglion cell diseases or to test neuroprotective strategies. If specific medium components can substantially extend ganglion cell survival, this opens two important avenues: first, the creation of longer-lived organoid models in which disease-relevant cell types remain available for study; and second, the identification of the trophic factors and metabolic conditions that ganglion cells require, which may themselves point toward therapeutic targets.

The mechanistic links between medium composition and cell survival likely involve several intersecting pathways. Oxidative stress is a prominent candidate, since retinal neurons are metabolically demanding and vulnerable to reactive oxygen species, and the antioxidant capacity of medium supplements such as those in B27 varies with formulation and with the degradation of components over time in culture. Energy metabolism is another: the retina is among the most oxygen-consuming tissues in the body, and photoreceptors in particular rely on aerobic glycolysis, a metabolic mode whose support depends on glucose and pyruvate availability in the medium. Growth factor signaling, including pathways involving BDNF, CNTF, GDNF, and insulin-like growth factors, also modulates ganglion cell survival, and the presence, stability, and concentration of such factors differ across media formulations. Even the buffering system and the resulting pH stability can influence neuronal health, as can osmolarity and the accumulation of metabolic waste products between medium changes.

For AAV transduction specifically, medium composition might act through effects on the cell surface. The glycocalyx, the dense layer of sugars coating the plasma membrane, provides attachment points that many AAV seruses exploit, and its composition is sensitive to culture conditions, including the availability of specific sugars and the activity of glycosyltransferases. Heparan sulfate proteoglycans serve as primary attachment receptors for several AAV serotypes, and sialic acid residues are critical for others. Media that alter glycosaminoglycan synthesis or sialylation could therefore change the efficiency of the initial binding step. Downstream, intracellular trafficking depends on the cytoskeleton and on endosomal pH, both of which can be modulated by medium components such as ammonium chloride accumulation, chloroquine-like compounds, or simply the energetic state of the cell. These mechanisms offer plausible, testable explanations for how the same vector applied to the same organoid type can perform differently across media.

The broader lesson resonates with a recurring theme in stem cell biology: the environment is part of the experiment. Organoids are often described as miniaturized versions of human tissues, but they are better understood as products of a continuous dialogue between intrinsic developmental programs and the culture environment. Small differences in oxygen tension, media exchange schedules, matrix composition, and the physical handling of cultures have all been shown to affect organoid morphology and cell type composition. The present findings add media formulation to this list in a way that directly touches two of the most translationally important readouts: gene delivery efficiency and survival of a clinically critical neuron.

From a practical standpoint, laboratories working with retinal organoids for gene therapy applications should consider several measures. Detailed documentation of medium composition, including lot numbers of supplements whose activity varies between batches, would improve reproducibility across the field. Cross-validation of key results in at least two distinct media formulations would reveal whether findings are robust or condition-dependent. Where possible, matching the metabolic and trophic environment of the organoid to the physiological state of the target tissue in vivo would improve the clinical relevance of preclinical testing. For ganglion cell studies specifically, optimizing media for survival may need to be balanced against the goal of photoreceptor maturation, since conditions that favor one cell class may not favor another, and the developmental timing of these requirements may differ.

There are also implications for disease modeling. Many inherited retinal diseases are cell-type specific, and the value of an organoid model depends on maintaining the relevant cells in a state that resembles their in vivo counterpart. Ganglion cell loss in culture has limited the use of organoids for modeling optic neuropathies such as those caused by mutations in OPA1 or other genes affecting mitochondrial function. If optimized media extend ganglion cell survival substantially, models of these diseases become feasible, enabling the study of pathogenesis in a human developmental context and the screening of candidate neuroprotective compounds. Similarly, for glaucoma research, where the interplay between elevated intraocular pressure, axonal transport disruption, and somal survival is difficult to disentangle in animal models, longer-lived organoid systems with robust ganglion cell populations would provide a complementary human platform.

The intersection with AAV biology deserves particular attention as the gene therapy field matures. Dose-limiting toxicity, immune responses, and the challenge of achieving pan-retinal transduction after intravitreal delivery remain central obstacles. Organoids offer a human-relevant system in which to evaluate candidate capsids, promoters, and expression cassettes, but their utility depends on the transduction results reflecting what would occur in a patient retina. The finding that media promote or suppress transduction suggests that part of the variability reported across organoid studies of AAV tropism may be attributable to culture conditions rather than to genuine differences in vector performance. Disentangling these variables will require systematic comparisons in which identical vectors are applied to organoids raised in parallel under different media conditions, with careful quantification of both transduction efficiency and the cell-type composition of the tissues.

It is also worth considering how these findings fit into the larger regulatory and manufacturing landscape. As retinal organoids move toward use in potency assays and release testing for cell and gene therapy products, the dependence of their properties on media composition becomes a matter of product consistency. Regulatory frameworks emphasize the characterization of critical quality attributes, and for organoid-based assays, the culture medium is arguably a critical reagent whose composition must be controlled with the same rigor as the biological material itself. Manufacturers of media and supplements may need to provide more detailed specifications, and users may need to implement qualification procedures for each new lot, particularly for supplements such as B27 whose complex composition includes components with variable biological activity.

Looking forward, the systematic mapping of how individual medium components affect retinal organoid physiology could yield a design framework for culture conditions tailored to specific applications: media optimized for photoreceptor maturation for studies of inherited photoreceptor degenerations, media optimized for ganglion cell survival for optic neuropathy models, and media that support efficient AAV transduction for vector validation studies. Such an approach would treat the medium as an engineering variable rather than a fixed convention, transforming a source of uncontrolled variability into a tool for shaping organoid properties. The present work, by demonstrating that culture media alter both AAV transduction and retinal ganglion cell survival in retinal organoids, provides both a caution about the interpretation of existing organoid studies and a constructive starting point for this more deliberate approach to organoid culture design.

Subject of Research: Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival

Article Title: Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival

Article References: O’Hara-Wright, M., Lim, B. Y., M. Mangala, M., Kaiser, V., Wong, E., Aubin, D., Nemeruck, V., Reynisson, H., Doroudian, F., Chan, O. P. Y., Aryamanesh, N., A. Paulo, J., Palomba, S., Mirzaei, M., Ginn, S. L., & Gonzalez-Cordero, A. (2026). Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival. Gene Therapy. https://doi.org/10.1038/s41434-026-00642-0

Image Credits: AI Generated

DOI: 10.1038/s41434-026-00642-0

Keywords: Culture, media, alter, retinal, organoid, physiology, promoting, transduction, ganglion, cell, survival, scientific research