Short-term monocular deprivation boosts neural responsiveness to audio-visual events for the undeprived eye

A brief period of monocular deprivation (MD) induces short-term plasticity of the adult visual system. Whether MD elicits changes beyond visual processing is yet unclear. Here, we assessed the specific impact of MD on multisensory processes. Neural oscillations associated with visual and audio-visual processing were measured for both the deprived and the undeprived eye. Results revealed that MD changed neural activities associated with unimodal and multisensory processes in an eye-specific manner. Selectively for the deprived eye, alpha activity was reduced within the first 150 ms of visual processing. Conversely, gamma activity was enhanced in response to audio-visual events only for the undeprived eye within 100-300 ms after stimulus onset. The analysis of gamma responses to unimodal auditory events revealed that MD elicited a crossmodal upweighting for the undeprived eye. Distributed source modeling suggested that the right parietal cortex played a major role in all neural effects induced by MD. Finally, visual and audio-visual processing alterations emerged selectively for the induced (but not the evoked) component of the neural oscillations, indicating a major role of feedback connectivity. These findings support a model in which MD increases excitability to visual events for the deprived eye and to audio-visual and auditory events for the undeprived eye. On the one hand, these results reveal the causal impact of MD on both unisensory and multisensory processes but with distinct frequency-specific profiles. On the other hand, they highlight the feedback nature of short-term neural plasticity. Overall this study shed light on the high flexibility and interdependence of unimodal and multisensory functions.