The review meticulously examines a wide array of studies aimed at dissecting the gut-brain axis through fecal transplantation. The promise of FMT lies in its ability to recapitulate, in an animal model, the complex microecological changes observed in human psychiatric conditions. However, the authors highlight significant methodological discrepancies across studies, including variations in donor selection criteria, fecal preparation methods, recipient conditioning protocols, and outcome assessment measures.

Among the core challenges underscored is the heterogeneity of donor psychiatric diagnoses. Psychiatric illnesses, ranging from depression and anxiety to schizophrenia and bipolar disorder, exhibit diverse pathophysiological profiles that influence gut microbial composition. The review stresses the imperative need for standardized diagnostic criteria and thorough clinical characterization of donors to ensure reproducibility and interpretability of results. Without harmonized donor inclusion parameters, inter-study comparability remains severely compromised.

The fecal sample preparation itself is a pivotal factor affecting transplant efficacy. Techniques vary widely, from fresh stool homogenization to cryopreserved samples, and differences in anaerobic handling can drastically alter microbial viability. Some protocols incorporate additional processing steps such as filtering or diluting, which may selectively skew microbial communities. The review advocates for a consensus on optimal fecal preparation methods that preserve community integrity while maintaining practical feasibility for widespread application.

Recipient mice conditioning prior to FMT is another major variable impacting experimental outcomes. Pre-treatment with antibiotics to eradicate endogenous microbiota or germ-free environments are standard approaches, yet each harbors inherent limitations. Antibiotic regimens differ in spectrum, duration, and timing, influencing the niche available for donor microbiota engraftment. Germ-free conditions, though ideal experimentally, are resource-intensive and not universally accessible. The review calls for a balanced, harmonized conditioning strategy underpinned by mechanistic understanding of microbiota colonization dynamics.

Functional readouts post-transplantation are equally diverse, encompassing behavioral, neurochemical, immunological, and metabolic parameters. While many studies report alterations in anxiety-like or depressive-like behaviors in recipient mice corresponding to donor psychiatric status, the variability in behavioral testing paradigms adds complexity to cross-study comparisons. Neuroinflammatory markers and neurotransmitter profiles occasionally complement behavioral data but lack uniform measurement standards. Such fragmented reporting inhibits meta-analytical synthesis and translational extrapolation.

Delving deeper, the review discusses the emerging mechanistic insights derived from psychiatric FMT models. Altered microbial communities appear capable of modulating neuroimmune pathways, hypothalamic-pituitary-adrenal axis activity, and neurotransmission. Metabolites such as short-chain fatty acids, tryptophan derivatives, and bile acids bridge the luminal and central nervous systems, suggesting novel therapeutic targets. Deciphering these mechanisms requires integrative approaches combining multi-omics, neurophysiology, and behavioral neuroscience, an endeavor the authors urge for robust methodological frameworks.

Beyond the laboratory, the translational implications of psychiatric FMT are profound yet currently nascent. Harnessing gut microbiota modulation to ameliorate psychiatric symptoms could revolutionize treatment paradigms, offering adjunctive or alternative strategies to pharmacotherapy. However, the review prudently cautions against premature clinical extrapolation without standardized preclinical rigor. It stresses the importance of validity, reproducibility, and comprehensive mechanistic understanding before embarking on human trials.

The ethical considerations surrounding psychiatric donor stool also receive attention. Standard fecal donor screening protocols primarily focus on infectious and gastrointestinal health, but psychiatric conditions add layers of complexity regarding informed consent, privacy, and stigma. Ethical frameworks tailored to psychiatric microbiota transplantation are urgently needed to navigate these challenges responsibly.

This exhaustive review functions as both a mirror and a roadmap for the psychiatric microbiota transplantation research community. By cataloging the spectrum of current methodological practices and pinpointing critical gaps, it provides a foundation for consensus-building efforts. The authors recommend collaborative networks to develop standardized protocols encompassing donor selection, fecal processing, recipient preparation, and outcome measures, fostering comparability and accelerating progress.

In conclusion, the field of fecal microbiota transplantation from psychiatric patients to mice is rapidly evolving but remains methodologically fragmented. This systematic review from D’Onofrio et al., published in Transl Psychiatry, serves as a pivotal resource highlighting the promise and pitfalls inherent in current practices. The call for methodological standardization is not merely academic—it is essential for transforming microbiota research into clinically actionable insights that could reshape mental health care. Future research anchored in harmonized protocols holds the key to unraveling the gut-brain axis mysteries and realizing the full therapeutic potential of microbiome modulation in psychiatry.

Subject of Research:
Fecal microbiota transplantation methodologies involving psychiatric patient donors and murine recipients to explore gut-brain axis interactions in neuropsychiatric disorders.

Article Title:
Fecal microbiota transplantation from psychiatric patients to mice – systematic review of methodologies and a call for standardization.

Article References:
D’Onofrio, A.M., Gomez-Nguyen, A., Camardese, G. et al. Fecal microbiota transplantation from psychiatric patients to mice – systematic review of methodologies and a call for standardization. Transl Psychiatry (2026). https://doi.org/10.1038/s41398-026-03847-4

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41398-026-03847-4

Escape responses in animals are crucial, evolutionarily conserved behaviors enabling survival through the rapid evasion of threats. In Drosophila, these reflexive responses can be triggered by sudden sensory stimuli—such as abrupt visual, acoustic, or tactile cues—eliciting a swift flight or jump. What this new study elucidates is how a sub-threshold, non-startling pre-stimulus (or pre-pulse) can suppress or tune down the subsequent startle response triggered by a more intense stimulus. This regulatory mechanism, known as pre-pulse inhibition, reflects the nervous system’s capacity to filter and prioritize incoming stimuli, preventing overstimulation and allowing more adaptive behavioral reactions.

Traditionally, PPI has been extensively characterized in vertebrates, particularly mammals, as a model for sensory gating deficits commonly observed in neuropsychiatric disorders such as schizophrenia and bipolar disorder. However, until now, the precise neural and genetic underpinnings of PPI remained elusive in simpler model organisms like fruit flies. The new findings decisively establish Drosophila as a viable and powerful platform for dissecting the molecular and circuit-level mechanisms underlying PPI, providing a novel window into the evolution and functional significance of sensory gating.

The research team, led by Viragh, Asztalos, Fenckova, and colleagues, employed an integrated approach combining behavioral assays, electrophysiological recordings, and genetic manipulation to systematically characterize PPI in adult fruit flies. They designed carefully calibrated pre-pulse and pulse stimuli to measure how preceding subtle sensory cues modulate the subsequent escape jump reflex—a behavior robustly quantifiable thanks to Drosophila’s well-mapped neural circuitry.

One of the study’s pivotal discoveries was that while the initial tactile pre-pulse alone elicited no overt startle, it significantly reduced the magnitude of the escape response triggered by a subsequent stronger sensory pulse. This inhibition was consistent across experimental replicates, underscoring a reliable sensorimotor gating phenomenon. Importantly, the effect was stimulus-parameter dependent, highlighting intricate temporal and intensity thresholds governing neural integration in the fly’s nervous system.

Delving deeper, the researchers explored the genetic substrates implicated in this sensorimotor filtering process. Leveraging powerful genetic tools unique to Drosophila, including targeted mutations and neuron-specific silencing, they identified key molecules and neuronal populations critical for PPI expression. Notably, modulation of neurotransmitter systems previously associated with mammalian PPI—such as dopaminergic and glutamatergic pathways—produced significant alterations in the pre-pulse inhibitory response, suggesting conserved neurochemical mechanisms.

These findings have profound implications beyond entomological interest. By dissecting how the fruit fly brain implements sensory gating, scientists can draw parallels to human neuropsychiatric conditions characterized by disrupted PPI and sensory processing anomalies. The simplicity and genetic tractability of Drosophila afford unparalleled opportunities to uncover new candidate genes, signaling pathways, and circuit dynamics that may underlie disorders marked by impaired sensorimotor gating.

Moreover, the methods established in this study pave the way for high-throughput screening of neuroactive pharmacological compounds within a genetically defined framework. This advancement could accelerate preclinical testing pipelines for drugs targeting sensorimotor gating dysfunction, propelling translational research from bench to bedside with greater efficiency.

Intriguingly, the demonstration of PPI in an invertebrate species also adds a new dimension to understanding how complex adaptive behaviors evolve and are maintained across phylogenetic hierarchies. It challenges the notion that such sophisticated neural filtering mechanisms are exclusive to vertebrate brains, suggesting an ancient evolutionary origin and potentially convergent evolution of sensory gating.

The study further elaborates on the temporal architecture of PPI, revealing that the timing between the pre-pulse and the main pulse stimulus is critical—a feature shared with vertebrate systems. This temporal dependency implies a tightly regulated internal clock mechanism that orchestrates sensory processing and motor output, a fascinating target for future in vivo imaging and computational modeling studies.

Beyond individual neurons, the authors propose that networks encompassing interneurons within the Drosophila central nervous system integrate multisensory information to modulate escape behaviors adaptively. This network-level perspective echoes emerging views in neuroscience that sensory gating arises from distributed neural circuits interacting dynamically rather than isolated loci.

Importantly, the research takes a holistic approach by combining behavioral phenotyping with molecular and electrophysiological data, illustrating a multi-dimensional understanding of sensorimotor gating. This integrative methodology exemplifies the future of neuroscience, where bridging scales from molecules to behavior leads to transformative insights.

As the global scientific community seeks models that can balance complexity and experimental accessibility, this study elevates the fruit fly as an indispensable organism for neuropsychiatric research innovation. The ability to monitor and manipulate discrete neural circuits responsible for PPI in a live behaving animal situates Drosophila in the forefront of systems neuroscience.

In sum, the authors have compellingly demonstrated that adult Drosophila exhibit robust pre-pulse inhibition of escape responses, governed by genetically conserved neural mechanisms. This discovery does more than fill a gap—it opens a vast new research domain linking fundamental neurobiology with translational psychiatry, presenting an elegant and practical system to unravel the mysteries of sensory processing and behavioral modulation.

With this pivotal work, the scientific community is now poised to harness the power of Drosophila genetics and neurophysiology to deepen our understanding of brain function and dysfunction, ultimately guiding the development of novel therapies for disabling neuropsychiatric conditions characterized by sensory gating deficits. The future of sensorimotor research has taken flight, propelled by the humble fruit fly’s remarkable behavioral repertoire.

Subject of Research: Pre-Pulse Inhibition and sensorimotor gating mechanisms in adult Drosophila melanogaster.

Article Title: Pre-Pulse Inhibition of an escape response in adult fruit fly, Drosophila melanogaster.

Article References:
Viragh, E., Asztalos, L., Fenckova, M. et al. Pre-Pulse Inhibition of an escape response in adult fruit fly, Drosophila melanogaster. Transl Psychiatry (2026). https://doi.org/10.1038/s41398-025-03717-5

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41398-025-03717-5

Microstates are brief periods, milliseconds in duration, during which the brain’s global electrical activity exhibits a consistent topographic pattern. In humans, these microstates are thought to represent the ‘building blocks’ of cognitive processing and reflect coordinated brain network activity underlying perception, attention, and consciousness. Until now, capturing these subtle but revealing electrical signatures in non-human animals has been technically challenging due to differences in brain architecture and EEG recording methodologies. This study innovatively bridges that gap by demonstrating that rats too display definable microstate dynamics, providing a powerful preclinical platform to explore neuropsychiatric disorders.

The researchers employed advanced EEG recording techniques adapted for the rodent brain, ensuring high-resolution temporal and spatial data acquisition. Their methodology involved recording electrical activity from the cortical surface while rats engaged in resting and behavioral tasks. By applying computational algorithms traditionally used in human EEG microstate analysis, the team uncovered distinct microstate classes in rat EEG data, analogous in temporal parameters and spatial topographies to human counterparts. This approach validates the translational potential of rodent microstate research to human cognitive neuroscience.

One of the study’s most compelling findings is that rat microstates are characterized by a unique repertoire of topographies that persist for tens of milliseconds, mirroring human EEG microstate durations. Such temporal stability indicates an organized neural basis for these microstates across species. This revelation challenges assumptions that microstates are exclusive to the complex human cerebral cortex, instead positing that microstate-like phenomena may be a fundamental neurophysiological principle conserved through evolution.

The authors also explored how different behavioral states influence microstate dynamics in rats. They discovered that transitions between microstate classes correlated with changes in behavioral context, akin to observations in human EEG studies where microstate configurations fluctuate with cognitive demands and emotional states. This behavioral linkage confirms that rat microstates are not ephemeral artifacts, but robust neural signatures tied to brain function.

Another salient component of the study was the examination of microstate alterations induced by psychopharmacological manipulations. By administering drugs affecting neurotransmitter systems implicated in psychiatric disorders, the team observed predictable modulations in microstate parameters. These pharmacological effects underscore the utility of rat microstate analysis in preclinical models for drug development and screening for psychiatric therapeutics.

Technically, the study leverages machine learning and sophisticated signal processing pipelines to segment continuous EEG data into discrete microstates. This automated classification enables objective quantification of microstate features such as duration, occurrence, and transition probabilities. Such detailed characterization surpasses traditional EEG analyses and opens avenues for detailed mechanistic insights into brain network dynamics underpinning behavior and mental health.

The implications of this proof-of-concept study are vast and multifaceted. By establishing microstate analysis in rats, researchers now have access to a powerful experimental platform where invasive techniques, genetic manipulations, and longitudinal studies can elucidate the neural substrates of microstate phenomena. This addresses a critical limitation in human EEG research, where non-invasive recordings restrict mechanistic explorations.

Moreover, this research paves the way for innovative translational applications. Microstate abnormalities are emerging biomarkers in psychiatric conditions such as schizophrenia, depression, and bipolar disorder. Understanding how these microstate configurations arise, stabilize, or degrade in animal models that recapitulate human psychopathologies can accelerate the development of targeted interventions and personalized medicine strategies.

The study also emphasizes the evolutionary conservation of brain network dynamics. By pinpointing microstates in rodents, the findings suggest that the neural architecture responsible for generating these patterns is deeply rooted in mammalian brain organization, reflecting fundamental principles of cognitive processing and consciousness. This cross-species perspective invites a reevaluation of how we conceptualize mental processes in non-human animals.

From a methodological standpoint, the successful adaptation of human EEG microstate analytical frameworks to rats signifies a methodological breakthrough. It underscores the value of interdisciplinary approaches combining neuroengineering, computational neuroscience, and behavioral neurobiology. Such integration is vital to unravel the complex interactions between neuronal populations that manifest as emergent global electrical states.

The researchers also highlight that while similarities exist between human and rodent microstates, species-specific differences in microstate topology and dynamics reflect divergent anatomical and functional brain features. Careful comparative analyses will be essential to interpret translational findings appropriately, ensuring that rodent models accurately recapitulate key aspects of human brain function.

In addition to behavioral correlations, the study reveals that microstate transitions exhibit non-random patterns influenced by underlying neural oscillations and connectivity networks. This insight suggests that microstates are emergent properties of coordinated neuronal ensembles engaging transiently to support information processing. Deciphering these interactions at fine temporal scales enriches our understanding of brain function beyond traditional firing rate or connectivity metrics.

Critically, the team calls for future research incorporating simultaneous EEG and invasive electrophysiological recordings in rodents to map microstates onto cellular and circuit-level processes. Such multimodal approaches will clarify how neuronal spiking and synaptic interactions generate the macroscopic microstate activity observed in EEG. This multilayered analysis is poised to unravel the biological meaning of microstates and their relevance to cognition and disease.

This pioneering study stands at the forefront of neural network research, promising to revolutionize how we investigate brain states and their perturbations in health and disease. By demonstrating that rats share key microstate properties with humans, it establishes a vital translational bridge, fostering advancements in psychiatric research, neuropharmacology, and cognitive neuroscience.

In summation, the proof-of-concept achievement of detecting and characterizing microstates in rat EEG not only validates a novel biomarker for brain function but also opens a rich vein of scientific inquiry into the neural bases of cognition, emotion, and neuropsychiatric disorders. The work of Piorecka et al. heralds a new era in which rodent models can be intimately leveraged to decipher the complexities of brain network dynamics observable non-invasively in humans.

Subject of Research: Neural microstates as observed in electroencephalography (EEG) of rats, investigating their similarities with human EEG microstates to advance translational psychiatry.

Article Title: Microstate in rats’ EEG: a proof of concept study.

Article References:
Piorecka, V., Vejmola, C., Peskova, P. et al. Microstate in rats’ EEG: a proof of concept study. Transl Psychiatry 15, 494 (2025). https://doi.org/10.1038/s41398-025-03702-y

Image Credits: AI Generated

DOI: 10.1038/s41398-025-03702-y (Published November 21, 2025)