New findings from Weizmann Institute of Science, Department of Neurobiology in the area of life sciences described
2009 JUN 30 - (NewsRx.com) -- Scientists discuss in 'Seeing with profoundly deactivated mid-level visual areas: non-hierarchical functioning in the human visual cortex' new findings in life sciences. "A fundamental concept in visual processing is that activity in high-order object-category distinctive regions (e.g., lateral occipital complex, fusiform face area, middle temporal+) is dependent on bottom-up flow of activity in earlier retinotopic areas (V2, V3, V4) whose main input originates from primary visual cortex (V1). Thus, activity in down stream areas should reflect lower-level inputs," scientists writing in the journal Cerebral Cortex report. "Here we qualify this notion reporting case LG, a rare case of developmental object agnosia and prosopagnosia. In this person, V1 was robustly activated by visual stimuli, yet intermediate areas (V2-V4) were strongly deactivated. Despite this intermediate deactivation, activity in down stream visual areas remained robust, showing selectivity for houses and places, while selectivity for faces and objects was impaired. The extent of impairment evident in functional magnetic resonance imaging and electroencephalography activations was somewhat larger in the left hemisphere. This pattern of brain activity, coupled with fairly adequate everyday visual performance is compatible with models emphasizing the role of nonlinear local 'amplification' of neuronal inputs in eliciting activity in ventral and dorsal visual pathways as well as perceptual experience in the human brain," wrote S. Gilaie-Dotan and colleagues, Weizmann Institute of Science, Department of Neurobiology. The researchers concluded: "Thus, while the proper functioning of intermediate areas appears essential for specialization in the cortex, daily visual behavior and reading are maintained even with deactivated intermediate visual areas." Gilaie-Dotan and colleagues published their study in Cerebral Cortex (Seeing with profoundly deactivated mid-level visual areas: non-hierarchical functioning in the human visual cortex. Cerebral Cortex, 2009;19(7):1687-703). Additional information can be obtained by contacting S. Gilaie-Dotan, Weizmann Institute of Science, Dept. of Neurobiology, Rehovot, Israel. The publisher of the journal Cerebral Cortex can be contacted at: Oxford University Press, Great Clarendon St., Oxford OX2 6DP, England. Keywords: Israel, Rehovot, Life Sciences, Prosopagnosia, Agnosia, Neurobiology. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2009, Life Science Weekly via NewsRx.com.
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