Demaria, R.; Moinon, A.; Negrel, T.; Sutter, C.; Blouin, J.; Simoneau, M.; Mouchnino, L.

Strikingly, highly trained athletes engaged in vertiginous activities (e.g., dance and slacklining) and patients with bilateral vestibular loss show a similar pattern of neural plasticity, likely resulting from reduced vestibular sensory processes. However, unlike patients, these athletes show no balance impairments, quite the opposite. This suggests that the attenuation of vestibular processing represents an adaptive recalibration to excessive vestibular stimulation rather than a sign of dysfunction. Concurrently, tactile processing increases as vestibular processing attenuates. Our findings indicate that effective adaptation extends beyond simple tactile compensation: it involves a strengthened tactile-brain pathway. Indeed, following unexpected base-of-support translations, the coupling between plantar shear forces (i.e., a proxy of plantar sole tactile afferents) and cortical responses over the somatosensory areas was markedly enhanced in Athletes. Cross-correlation analysis revealed stronger (r = 0.71) and faster (36 ms) tactile-brain coupling in Athletes (n = 25) compared with age- and gender-matched Controls (n = 18). This enhancement occurred within the first 180 ms following translation, that is, during the critical early phase of skin-surface interaction. Notably, artistic swimmers, who undergo intense vestibular stimulation in a weightless underwater environment without balance equilibrium constraints, also exhibit enhanced tactile-brain coupling. This suggests that strengthening the tactile-brain coupling is not merely a byproduct of balance expertise, but rather a broader adaptive response to sustained vestibular stimulation. Multimodal neurons integrating vestibular and somatosensory inputs, such as those in the somatosensory cortex and thalamus, may increase their responsiveness to foot tactile afferents when vestibular inputs become excessive. In such contexts, the somatosensory system may assume a dominant role in providing gravity-related information for balance control.