Electrophysiological correlates of associative visual agnosia lesioned in the ventral pathway

Takao Yamasaki, Takayuki Taniwaki, Shozo Tobimatsu, Kenji Arakawa, Hiroshi Kuba, Yoshihisa Maeda, Yasuo Kuwabara, Kenshiro Shida, Yasumasa Ohyagi, Takeshi Yamada, Jun Ichi Kira

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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.

Original languageEnglish
Pages (from-to)53-60
Number of pages8
JournalJournal of the Neurological Sciences
Volume221
Issue number1-2
DOIs
Publication statusPublished - Jun 15 2004

All Science Journal Classification (ASJC) codes

  • Neurology
  • Clinical Neurology

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    Yamasaki, T., Taniwaki, T., Tobimatsu, S., Arakawa, K., Kuba, H., Maeda, Y., Kuwabara, Y., Shida, K., Ohyagi, Y., Yamada, T., & Kira, J. I. (2004). Electrophysiological correlates of associative visual agnosia lesioned in the ventral pathway. Journal of the Neurological Sciences, 221(1-2), 53-60. https://doi.org/10.1016/j.jns.2004.03.024