Grasso, P. A., Benassi, M., Làdavas, E., & Bertini, C.
Audio‐visual multisensory training enhances visual processing of motion stimuli in healthy participants: an electrophysiological study
European Journal of Neuroscience, 44(10), 2748–2758
Evidence from electrophysiological and imaging studies suggests that audio-visual (AV) stimuli presented in spatial coincidence enhance activity in the subcortical colliculo-dorsal extrastriate pathway. To test whether repetitive AV stimulation might speciﬁcally activate this neural circuit underlying multisensory integrative processes, electroencephalographic data were recorded before and after 2 h of AV training, during the execution of two lateralized visual tasks: a motion discrimination task, relying on activity in the colliculo-dorsal MT pathway, and an orientation discrimination task, relying on activity in the striate and early ventral extrastriate cortices. During training, participants were asked to detect and perform a saccade towards AV stimuli that were disproportionally allocated to one hemiﬁeld (the trained hemiﬁeld). Half of the participants underwent a training in which AV stimuli were presented in spatial coincidence, while the remaining half underwent a training in which AV stimuli were presented in spatial disparity (32°). Participants who received AV training with stimuli in spatial coincidence had a post-training enhancement of the anterior N1 component in the motion discrimination task, but only in response to stimuli presented in the trained hemiﬁeld. However, no effect was found in the orientation discrimination task. In contrast, participants who received AV training with stimuli in spatial disparity showed no effects on either task. The observed N1 enhancement might reﬂect enhanced discrimination for motion stimuli, probably due to increased activity in the colliculo-dorsal MT pathway induced by multisensory training.