Visual area V5/hMT+ contributes to perception of tactile motion direction: a TMS study

Tomohiro Amemiya,Vincent Walsh,Patrick Haggard,Hiroaki Gomi,Brianna Beck

doi:10.1038/srep40937

Abstract

Human imaging studies have reported activations associated with tactile motion perception in visual motion area V5/hMT+, primary somatosensory cortex (SI) and posterior parietal cortex (PPC; Brodmann areas 7/40). However, such studies cannot establish whether these areas are causally involved in tactile motion perception. We delivered double-pulse transcranial magnetic stimulation (TMS) while moving a single tactile point across the fingertip, and used signal detection theory to quantify perceptual sensitivity to motion direction. TMS over both SI and V5/hMT+, but not the PPC site, significantly reduced tactile direction discrimination. Our results show that V5/hMT+ plays a causal role in tactile direction processing, and strengthen the case for V5/hMT+ serving multimodal motion perception. Further, our findings are consistent with a serial model of cortical tactile processing, in which higher-order perceptual processing depends upon information received from SI. By contrast, our results do not provide clear evidence that the PPC site we targeted (Brodmann areas 7/40) contributes to tactile direction perception.

Highlights

Human imaging studies have reported activations associated with tactile motion perception in visual motion area V5/hMT+, primary somatosensory cortex (SI) and posterior parietal cortex (PPC; Brodmann areas 7/40)
Our predictions focussed on whether transcranial magnetic stimulation (TMS) at each active site influenced motion perception relative to sham TMS; our key inferences are based on comparisons between each active TMS condition and the sham TMS conditions
Compared to the sham condition (M = 76.1%, SD = 11.1%), participants were less accurate when TMS was applied over SI (M = 66.9%, SD = 14.0%; t(51) =−3.66, padj = 0.0036, Cohen’s d = 0.73) and over V5/hMT+(M = 68.6%, SD = 12.0%; t(51) =−2.99, padj = 0.021, Cohen’s d = 0.65), but not over PPC (M = 70.7%, SD = 13.5%; t(51) =−2.16, padj = 0.140, Cohen’s d = 0.44) (Fig. 2a)