Differential effect of visual motion adaption upon visual cortical excitability

Objective: 1) To probe the effects of visual motion adaptation upon, early visual and V5/MT cortical excitability and 2) To investigate whether or not changes in cortical excitability following visual motion adaptation are related to the degree of visual dependency, i.e. an overreliance on visual cues compared to vestibular or proprioceptive cues. Methods: Participants were exposed to a roll-motion visual stimulus pre, during and post visual motion adaptation. At these stages 20 TMS pulses at phosphene-threshold values were applied over early visual and V5/MT cortical areas from which the probability of eliciting a phosphene was calculated. Pre and post adaptation, participants aligned the subjective visual vertical in front of the roll-motion stimulus as a marker of visual dependency. Results: During adaptation, early visual cortex excitability decreased while V5/MT excitability increased. After adaptation, both early visual and V5/MT excitability were increased. The roll-motion induced tilt of the subjective visual vertical (visual dependence) was not influenced by visual motion adaptation and did not correlate with phosphene threshold or visual cortex excitability. Conclusions: Early visual and V5/MT cortical excitability is differentially affected by visual motion adaptation. Furthermore, excitability in the early or late visual cortex is not associated with an increase in visual reliance during spatial orientation. Significance: Our findings complement earlier studies that have probed visual cortical excitability following motion adaptation and highlight the differential role of the early visual cortex and V5/MT in visual motion processing.

from Physiology via xlomafota13 on Inoreader http://ift.tt/2fNRfVK
via IFTTT