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J Neurophysiol. 2017 Nov 1;118(5):2614-2627. doi: 10.1152/jn.00113.2017. Epub 2017 Aug 16.

Face percept formation in human ventral temporal cortex.

Author information

1
Department of Neurosurgery, Stanford University, Stanford, California; kai.miller@stanford.edu.
2
Program in Neurobiology and Behavior, University of Washington, Seattle, Washington.
3
Department of Psychology, Stanford University, Stanford, California.
4
Department of Psychology, Program in Neuroscience and Cognitive Science, and Indiana Network Science Institute, Indiana University, Bloomington, Indiana.
5
School of Behavioral & Brain Sciences, University of Texas at Dallas, Dallas, Texas.
6
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas; and.
7
Department of Neurological Surgery, University of Washington, Seattle, Washington.

Abstract

Loci in ventral temporal cortex are selectively active during viewing of faces and other objects, but it remains unclear whether these areas represent accumulation of simple visual information or processing of intact percept. We measured broadband electrocorticographic changes from implanted electrodes on the ventral temporal brain surface while showing patients noise-degraded images of faces and houses. In a subset of posterior fusiform gyrus face-selective regions, cortical activity decreased parametrically with noise increase, until the perceptual threshold was surpassed. At noise levels higher than the perceptual threshold, and for house stimuli, activity remained at baseline. We propose that this convergence of proportional and thresholded response may identify active areas where face percepts are extracted from simple visual features. These loci exist within a topological structure of face percept formation in the human ventral visual stream, preceded by category-nonselective activity in pericalcarine early visual areas and in concert with all-or-nothing activity in postperceptual subregions of the ventral temporal lobe. This topological organization suggests a physiological basis for the anatomy of face perception, explaining different perceptual deficits following temporal lobe injury.NEW & NOTEWORTHY Philosophers have puzzled for millennia about how humans build abstract conceptual objects (house/face/tool) from the simple features of the world they see around them (line/patch/lighting). Understanding the biological foundation of this process requires detailed knowledge of the spatial-temporal characteristics of cerebral cortex. By examining the physiology of the human temporal lobe via implanted electrodes while showing subjects noise-degraded images, we find that face percept formation happens in specific subregions within known face-processing areas.

KEYWORDS:

electrocorticography; face processing; human brain; perception; prosopagnosia; temporal lobe

PMID:
28814631
PMCID:
PMC5668462
DOI:
10.1152/jn.00113.2017
[Indexed for MEDLINE]
Free PMC Article

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