Preserved local but disrupted contextual figure-ground influences in an indi...

 

 

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Preserved local but disrupted contextual figure-ground influences in an individual with abnormal function of intermediate visual areas

via ScienceDirect Publication: Neuropsychologia on 3/7/12

Publication year: 2012
Source: Neuropsychologia, Available online 7 March 2012
Joseph L. Brooks, Sharon Gilaie-Dotan, Geraint Rees, Shlomo Bentin, Jon Driver
Visual perception depends not only on local stimulus features but also on their relationship to the surrounding stimulus context, as evident in both local and contextual influences on figure-ground segmentation. Intermediate visual areas may play a role in such contextual influences, as we tested here by examining LG, a rare case of developmental visual agnosia. LG has no evident abnormality of brain structure and functional neuroimaging showed relatively normal V1 function, but his intermediate visual areas (V2/V3) function abnormally. We found that contextual influences on figure-ground organization were selectively disrupted in LG, while local sources of figure-ground influences were preserved. Effects of object knowledge and familiarity on figure-ground organization were also significantly diminished. Our results suggest that the mechanisms mediating contextual and familiarity influences on figure-ground organization are dissociable from those mediating local influences on figure-ground assignment. The disruption of contextual processing in intermediate visual areas may play a role in the substantial object recognition difficulties experienced by LG.

Highlights

► We tested a developmental agnosic patient, LG. ► LG shows preserved local but impaired contextual influences on figure-ground. ► LG shows impaired familiarity influences on figure-ground ► Visual areas V2/V3 play a role in figure-ground context and familiarity effects ► Local, contextual, and familiarity figure-ground influences are dissociable

 

 

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