Perceptual segregation of overlapping shapes activates posterior extrastriate visual cortex in man

Experimental Brain Research
J LarssonP E Roland

Abstract

Objects in natural scenes are rarely seen in isolation, but are usually overlapping or partially occluding other objects. To recognize individual objects, the visual system must be able to segregate overlapping objects from one another. Evidence from lesions in humans and monkeys suggest that perceptual segregation of occluded or overlapping objects involves extrastriate visual cortex. In monkeys, area V4 has been shown to play an important role in recognizing occluded or poorly salient shapes. In humans, a retinotopic homologue of ventral V4 (V4v) has been described, but it is not known whether this area is also functionally homologous to area V4 in monkeys. In this study, we tried to localize the visual cortical regions involved in perceptual segregation of overlapping shapes using positron emission tomography (PET). Regional cerebral blood flow (rCBF) was measured in seven subjects while they discriminated the relative areas of simultaneously presented rectangular shapes. In the control condition, the shapes were displayed without overlaps; in a second condition, the shapes overlapped each other partially. In a third condition, the shapes did not overlap but had been reduced in salience by adding random noise to the stimuli....Continue Reading

Citations

Aug 11, 2007·NeuroImage·Esther Alonso PrietoPeter A Tass
Mar 4, 2011·Movement Disorders : Official Journal of the Movement Disorder Society·Toshiyuki IshiokaEtsuro Mori
Sep 27, 2005·NeuroImage·Maria G KnyazevaPhilippe Maeder
Feb 3, 2007·Human Brain Mapping·Claudia RottschyKatrin Amunts

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