title: A Direct Demonstration of Functional Differences between Subdivisions of Human V5/MT.
abstract: Two subdivisions of human V5/MT+: one located posteriorly (MT/TO-1) and the other more anteriorly (MST/TO-2) were identified in human participants using functional magnetic resonance imaging on the basis of their representations of the ipsilateral versus contralateral visual field. These subdivisions were then targeted for disruption by the application of repetitive transcranial magnetic stimulation (rTMS). The rTMS was delivered to cortical areas while participants performed direction discrimination tasks involving 3 different types of moving stimuli defined by the translational, radial, or rotational motion of dot patterns. For translational motion, performance was significantly reduced relative to baseline when rTMS was applied to both MT/TO-1 and MST/TO-2. For radial motion, there was a differential effect between MT/TO-1 and MST/TO-2, with only disruption of the latter area affecting performance. The rTMS failed to reveal a complete dissociation between MT/TO-1 and MST/TO-2 in terms of their contribution to the perception of rotational motion. On the basis of these results, MT/TO-1 and MST/TO-2 appear to be functionally distinct subdivisions of hV5/MT+. While both areas appear to be implicated in the processing of translational motion, only the anterior region (MST/TO-2) makes a causal contribution to the perception of radial motion.
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.|Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5DD, UK.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Strong
authors.affiliation: Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5DD, UK.|Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, USA.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Silson
authors.affiliation: Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5DD, UK.
authors.forename: André D
authors.initials: AD
authors.lastname: Gouws
authors.affiliation: Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5DD, UK.|Centre for Neuroscience, Hull-York Medical School, University of York, York, YO10 5DD, UK.
authors.forename: Antony B
authors.initials: AB
authors.lastname: Morland
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.
authors.forename: Declan J
authors.initials: DJ
authors.lastname: McKeefry
mesh_terms: D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D013647:Task Performance and Analysis; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: V5/MT+; fMRI; psychophysics; transcranial magnetic stimulation