title: First-order and second-order motion: neurological evidence for neuroanatomically distinct systems.
abstract: An unresolved issue in visual motion perception is how distinct are the processes underlying 'first-order' and 'second-order' motion. The former is defined by spatio-temporal variations of luminance and the latter by spatio-temporal variations in other image attributes such as contrast or depth, for example. Using neuroimaging and psychophysics we present data from four neurological patients with unilateral and mostly cortical infarcts, which strongly suggest that first- and second-order motion have a different neural substrate. We found that from the early stages of processing, these two types of motions are mediated by two distinct pathways: first-order motion is carried out by mechanisms along the dorsal pathway in the occipital lobe, while the second-order motion by mechanisms mostly along the ventral pathway. The data reported here also suggest that different cortical regions may be in charge of processing direction-discrimination in second-order motion defined by different second-order attributes.
authors.affiliation: Department of Biomedical Engineering, Brain and Vision Research Laboratory, Boston University, Department of Neurology, Harvard Medical School, Boston, MA 02215, USA. vaina@engc.bu.edu
authors.forename: Lucia M
authors.initials: LM
authors.lastname: Vaina
authors.forename: Sergei
authors.initials: S
authors.lastname: Soloviev
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D002544:Cerebral Infarction / Q000503:physiopathology*; D015350:Contrast Sensitivity; D003867:Depth Perception; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008029:Lighting; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception; D009778:Occipital Lobe / Q000503:physiopathology; D011601:Psychophysics; D014796:Visual Perception