TY - JOUR IS - 7 N1 - This work is made available under a Creative Commons license. PMCID: PMC3405515 SP - 1393 VL - 50 JF - Neuropsychologia A1 - Brooks, JL A1 - Gilaie-Dotan, S A1 - Rees, G A1 - Bentin, S A1 - Driver, J UR - http://dx.doi.org/10.1016/j.neuropsychologia.2012.02.024 SN - 0028-3932 TI - Preserved local but disrupted contextual figure-ground influences in an individual with abnormal function of intermediate visual areas. Y1 - 2012/06// AV - public EP - 1407 KW - Agnosia KW - Association KW - Brain Mapping KW - Frontal Lobe KW - Functional Laterality KW - Humans KW - Image Processing KW - Computer-Assisted KW - Magnetic Resonance Imaging KW - Male KW - Oxygen KW - Pattern Recognition KW - Visual KW - Photic Stimulation KW - Psychophysics KW - Semantics KW - Young Adult N2 - 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. ID - discovery1339025 ER -