Monica Gori^1,2, Helene Vitale², Andrew Bremner³, Caudio Campus²; ¹IHMC, USA and IIT, Italy, ²IIT, Italy, ³University of Birmingham, UK

Background. The mechanisms underlying the development of multisensory integration in sensory deprivation remain unclear. In recent years, our work has highlighted the importance of sensory interactions in scaffolding multisensory development. We have shown that vision plays a critical role in shaping both auditory and tactile integration. In the absence of vision, auditory spatial representations and body representations are altered, making audio–tactile integration more challenging for blind individuals compared to sighted peers. Methods. We examined behavioral responses and event-related potentials (ERPs) in 12 sighted (S) and 12 severely visually impaired (SVI) infants. Participants were presented with unisensory (auditory, tactile) and multisensory (congruent, incongruent) stimuli delivered to their hands in both uncrossed and crossed positions. Neural activity was recorded using a high-density 128-channel EGI system. Results and Discussion. Together, the unisensory results suggest that SVI infants remain anchored to body-centered coordinates in early development, whereas sighted infants shift toward an external reference frame, revealing a two-step tactile processing mechanism. Indeed, SVI infants showed heightened contralateral somatosensory responses in an early time window, which correlated exclusively with their behavioral reactions and showed no evidence of tactile remapping. In contrast, sighted infants exhibited a later ipsilateral somatosensory response aligned with their behavioral performance. This highlights vision’s specific contribution to developing somatosensory remapping from early life. Regarding multisensory processing, congruent stimuli elicited activation of integrative centro-parietal (CP) and fronto-central (FC) regions within 180–220 ms in both groups, indicating preserved multisensory integration. However, in an earlier window (105–120 ms), sighted infants showed greater temporo-parietal activation (associated with auditory processing), whereas SVI infants showed stronger centro-parietal activation (associated with somatosensory processing). Consistent with our previous behavioral work (Gori et al., Curr.Biol. 2021), these results support the hypothesis that visual deprivation shapes early multisensory spatial representations.

Acknowledgements: Acknowledgement: This work is funded by EU H2020, ERC StG' MySpace (No. 948349).