title: Electrophysiological correlates of associative visual agnosia lesioned in the ventral pathway.
abstract: Visual agnosia has been well studied by anatomical, neuropsychological and neuroimaging studies. However, functional changes in the brain have been rarely assessed by electrophysiological methods. We carried out electrophysiological examinations on a 23-year-old man with associative visual agnosia, prosopagnosia and cerebral achromatopsia to evaluate the higher brain dysfunctions of visual recognition. Electrophysiological methods consisted of achromatic, chromatic and category-specific visual evoked potentials (CS-VEPs), and event-related potentials (ERPs) with color and motion discrimination tasks. Brain magnetic resonance imaging revealed large white matter lesions in the bilateral temporo-occipital lobes involving the lingual and fusiform gyri (V4) and inferior longitudinal fasciculi due to multiple sclerosis. Examinations including CS-VEPs demonstrated dysfunctions of face and object perception while sparing semantic word perception after primary visual cortex (V1) in the ventral pathway. ERPs showed abnormal color perception in the ventral pathway with normal motion perception in the dorsal pathway. These electrophysiological findings were consistent with lesions in the ventral pathway that were detected by clinical and neuroimaging findings. Therefore, CS-VEPs and ERPs with color and motion discrimination tasks are useful methods for assessing the functional changes of visual recognition such as visual agnosia.
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Neurological Institute, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. yamasa@neurophy.med.kyushu-u.ac.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Yamasaki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Taniwaki
authors.forename: Shozo
authors.initials: S
authors.lastname: Tobimatsu
authors.forename: Kenji
authors.initials: K
authors.lastname: Arakawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kuba
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Maeda
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kuwabara
authors.forename: Kenshiro
authors.initials: K
authors.lastname: Shida
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Ohyagi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamada
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Kira
mesh_terms: D000328:Adult; D000377:Agnosia / Q000503:physiopathology*; D001921:Brain / Q000000981:diagnostic imaging*; D004569:Electroencephalography; D004594:Electrophysiology / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D019788:Fluorodeoxyglucose F18; D007839:Functional Laterality; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed; D014796:Visual Perception / Q000502:physiology*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18