title: The role of cortical area V5/MT+ in speed-tuned directional anisotropies in global motion perception.
abstract: Several different directional anisotropies have been found in global motion perception. The purpose of this study was to examine the role of the motion sensitive cortical area V5/MT+ in directional anisotropies for translational flow fields. Experiments 1 and 2 tested direction discrimination and detection of moving random dot patterns. When the speed of motion was 8 deg/s, lower coherence thresholds were found for centripetal relative to centrifugal hemifield motion. When the speed of motion was 1 deg/s, coherence thresholds were similar in all directions. Experiment 3 used fMRI to measure the BOLD response to different directions of motion at speeds of 1 and 8 deg/s. Greater activity was found in V5/MT+ for centripetal motion than for centrifugal motion at both speeds. These results suggest that V5/MT+ does play a role in directional motion anisotropies. This role is discussed with respect to visually-guided reaching and locomotion.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC, Canada. giaschi@interchange.ubc.ca
authors.forename: Deborah
authors.initials: D
authors.lastname: Giaschi
authors.forename: Amy
authors.initials: A
authors.lastname: Zwicker
authors.forename: Simon Au
authors.initials: SA
authors.lastname: Young
authors.forename: Bruce
authors.initials: B
authors.lastname: Bjornson
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012684:Sensory Thresholds; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology
chemical_list: D010100:Oxygen