The research team, led by investigators working on the neural control of interceptive actions, asked thirteen right-handed participants to sit before a monitor displaying a baseball game. A ball hit by a batter followed a quasi-parabolic trajectory across the screen, and the volunteers had to slide an outfielder along the bottom of the scene and press a mouse button at the exact moment the ball reached the outfielder’s hand. The setup, adapted from earlier work by the same group, recorded cursor position at 200 hertz and button presses at 1,000 hertz, while an eye tracker monitored gaze fixation at 500 hertz to ensure that participants kept their eyes locked on a windmill-shaped fixation point throughout each trial.

The critical twist was that the ball’s motion did not always obey physics as we know it. In half the trials, the descending portion of the trajectory abruptly shifted from gravitational acceleration to a constant-velocity profile, simulating a zero-gravity condition. This manipulation was designed to probe whether participants’ brains relied on an internalized model of gravity—a lifetime of experience with falling objects encoded in the vestibular network—or simply tracked the visual motion as it unfolded. In separate sessions, the ball either remained visible until landing or vanished from view 500 milliseconds after the trajectory perturbation, forcing the visual system to extrapolate the invisible remainder of the flight.

While participants performed this task, the researchers delivered triple-pulse transcranial magnetic stimulation—three pulses at 10 hertz through a figure-of-eight coil held in place by a mechanical arm and neuronavigation system—over four cortical sites on the left hemisphere: the middle temporal visual area MT/V5, the wide-field visual motion area V6, its visuomotor neighbor V6A, and a premotor region in the inferior frontal gyrus belonging to the vestibular network. The stimulation was applied either 100 or 600 milliseconds after the trajectory perturbation, and a Vertex control site was stimulated to account for nonspecific auditory and somatosensory artifacts of the coil discharge, which were masked with white noise played through in-ear earphones.

The results revealed a striking functional dissociation among the four areas. Disruption of MT/V5 produced the most robust and consistent effects, altering interception timing under both visible and occluded conditions. When the ball was fully visible, stimulation led participants to respond earlier than usual, consistent with the idea that MT/V5 activity modulates the central processing delays that would otherwise make our perception of moving objects lag behind reality. When the ball was occluded, however, the same stimulation delayed responses—particularly to zero-gravity trajectories—implying that MT/V5 contributes to visual motion extrapolation, possibly by maintaining a working memory buffer of the motion information processed before the target disappeared.

Area V6, located downstream of MT/V5 along the parieto-occipital sulcus, showed a more restricted profile. Its disruption altered interceptive timing only when trajectories were fully visible, with significant effects emerging only with the later stimulation window. This pattern suggests that V6 represents a processing stage downstream of MT/V5 that backs up the role of the motion area when visual information is continuously available, but does not participate in extrapolating occluded motion. Remarkably, stimulation of V6A—the visuomotor area immediately adjacent to V6 that integrates visual, somatosensory, and motor signals and has been causally implicated in reaching and grasping—produced no significant effects at all. The authors suggest that the two-dimensional trajectories confined to the frontal plane, and the absence of physical interaction with the ball, may have downplayed V6A’s role, which could be more engaged in tasks involving visual motion in depth and direct object contact.

The premotor site in the inferior frontal gyrus, selected because prior fMRI work showed it is activated preferentially by visual motion congruent with Earth’s gravity, produced consistent effects only with occluded motion. Its disruption delayed interceptive responses to both gravitational and zero-gravity trajectories, with a slight selectivity for gravitational motion in the spatial domain. This finding aligns with neuroimaging evidence that the same region activates when observing occluded compared to unoccluded motion, and implies that this premotor vestibular site may combine predictive signals about the occluded object’s motion—relayed from parietal areas—with internalized gravity information processed within the vestibular network, ultimately driving motor cortical activity to produce timed and spatially accurate responses.

The spatial aspects of interception proved less sensitive to cortical disruption than the temporal ones. Participants generally moved the mouse cursor close to the presumed landing location early in the trajectory and made only small adjustments afterward, which may explain why stimulation effects on cursor placement were much less consistent than those on response timing. Nevertheless, small but systematic differences emerged: disruption of MT/V5 and V6 led to underestimation of zero-gravity landing locations, while disruption of the inferior frontal gyrus produced overestimation of gravitational trajectories. These observations hint at a push–pull relationship between visual motion information and gravity a priori, in which increased reliance on internalized gravity predictions compensates for disrupted visual signals.

Altogether, the study supports a parallel distributed organization of the cortical network underlying interception, refining a scheme originally proposed from earlier work targeting MT/V5, the temporoparietal junction, and the intraparietal sulcus. According to the updated model, MT/V5 feeds predictive timing information to downstream areas including V6, posterior parietal regions, and vestibular network sites; when motion becomes occluded, it may supply a memory signal to intraparietal areas directly involved in extrapolation, while the inferior frontal gyrus integrates visual predictions with gravity a priori to drive the motor output. The context-dependent contributions of MT/V5—earlier responses with visible motion, delayed responses with occluded motion—suggest that the integration of sensory and predictive information is not a fixed computation but one that flexibly reorganizes depending on the availability of visual feedback.

Beyond its theoretical implications, the work demonstrates the power of causal perturbation approaches for dissecting complex visuomotor behavior. By comparing the effects of stimulation at anatomically adjacent sites such as V6 and V6A, which belong to separate cytoarchitectonic areas, the study also provides indirect evidence that the observed effects reflect genuine disruptions of cortical activity rather than nonspecific artifacts. Future studies using immersive setups with physical interaction with moving objects may clarify whether V6A contributes to interception under more naturalistic conditions, and whether the vestibular premotor network plays an even broader role in the predictive control of actions in three-dimensional space.

Subject of Research: Interception of visible and occluded ballistic trajectories: differential contributions by areas MT/V5, V6, V6A and the vestibular premotor cortex evaluated by TMS

Article Title: Interception of visible and occluded ballistic trajectories: differential contributions by areas MT/V5, V6, V6A and the vestibular premotor cortex evaluated by TMS

Article References: Delle Monache, S., Paolocci, G., Gamberini, M., Scalici, F., Indovina, I., Fattori, P., Galletti, C., Lacquaniti, F., & Bosco, G. (2026). Interception of visible and occluded ballistic trajectories: differential contributions by areas MT/V5, V6, V6A and the vestibular premotor cortex evaluated by TMS. Frontiers in Integrative Neuroscience, 20, Article 1907398. https://doi.org/10.3389/fnint.2026.1907398

Image Credits: AI Generated

DOI: 10.3389/fnint.2026.1907398

Keywords: Interception, visible, occluded, ballistic, trajectories, differential, contributions, areas, vestibular, premotor, cortex, evaluated