An enhanced role for right hV5/MT+ in the analysis of motion in the contra- and ipsi-lateral visual hemi-fields

Samantha L. Strong, Edward H. Silson, André D. Gouws, Antony B. Morland, Declan J. Mckeefry

Research output: Contribution to journalArticle

Abstract

Previous experiments have demonstrated that transcranial magnetic stimulation (TMS) of human V5/MT+, in either the left or right cerebral hemisphere, can induce deficits in visual motion perception in their respective contra- and ipsi-lateral visual hemi-fields. However, motion deficits in the ipsi-lateral hemi-field are greater when TMS is applied to V5/MT + in the right hemisphere relative to the left hemisphere. One possible explanation for this asymmetry might lie in differential stimulation of sub-divisions within V5/MT + across the two hemispheres. V5/MT + has two major sub-divisions; MT/TO-1 and MST/TO-2, the latter area contains neurons with large receptive fields (RFs) that extend up to 15° further into the ipsi-lateral hemi-field than the former. We wanted to examine whether applying TMS to MT/TO-1 and MST/TO-2 separately could explain the previously reported functional asymmetries for ipsi-lateral motion processing in V5/MT + across right and left cerebral hemispheres. MT/TO-1 and MST/TO-2 were identified in seven subjects using fMRI localisers. In psychophysical experiments subjects identified the translational direction (up/down) of coherently moving dots presented in either the left or right visual field whilst repetitive TMS (25 Hz; 70%) was applied synchronously with stimulus presentation. Application of TMS to MT/TO-1 and MST/TO-2 in the right hemisphere affected translational direction discrimination in both contra-lateral and ipsi-lateral visual fields. In contrast, deficits of motion perception following application of TMS to MT/TO-1 and MST/TO-2 in the left hemisphere were restricted to the contra-lateral visual field. This result suggests an enhanced role for the right hemisphere in processing translational motion across the full visual field.
Original languageEnglish
Article number112060
JournalBehavioural Brain Research
Volume372
Early online date25 Jun 2019
DOIs
Publication statusPublished - 17 Oct 2019

Bibliographical note

© 2020 Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

Funding: BBSRC (BB/N003012/1) and Silmo Academy Bursary 2017

Keywords

  • Contra-lateral
  • Ipsi-lateral
  • MST
  • MT
  • Motion
  • TMS

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