ERPs evidence of multisensory integration deficits in spinal cord injury

Spinal cord injury (SCI) is associated with deficits in multisensory integration-the ability to synthesize cross-modal information. This study explores the neural mechanisms underlying these deficits using EEG and a detection task incorporating unisensory and multisensory stimuli: audio-visual, visuo-tactile, and audio-tactile. Behaviorally, participants with SCI showed reduced multisensory integration across all modalities, consistent with prior findings. Neurally, ERPs were analyzed in three conditions: audio-tactile (N100, P200), visuo-tactile (P170), and audio-visual (P100, N200). Higher ERP amplitudes for multisensory versus unisensory stimuli were only observed in the control group, whereas the SCI group showed similar amplitudes across both. In the SCI group, multisensory ERPs were significantly lower for audio-tactile P200, visuo-tactile P170, and audio-visual P100, indicating a deficit in multisensory processing. Auditory ERPs were preserved in SCI participants, while visual and tactile responses were reduced, suggesting an auditory dominance post-SCI. Cluster-based analysis on residual effects showed that the control group exhibited greater multisensory gain compared to SCI participants, with significant centro-parietal clusters observed for audio-tactile (50-100 ms, 120-180 ms, 300-500 ms), visuo-tactile (80-120 ms, 120-180 ms), and audio-visual (280-480 ms) residual effects. Overall, these results highlight that SCI has detrimental effects not only on the motor system, but also on the ability to process multisensory information. This study advances our understanding of multisensory integration mechanisms following sensorimotor deficits and highlights the need for targeted interventions to address multisensory impairments in this population.