The functional organization of human extrastriate cortex: a PET-rCBF study of selective attention to faces and locations

TLDR

Our PET‑CBF study confirms that distinct extrastriate regions mediate face versus location perception, aligning with prior work and showing clear dissociations from color and motion areas. The study aimed to map the functional dissociation of extrastriate cortical streams for face identity and location perception in healthy men using PET‑rCBF during face‑matching, location‑matching, and control tasks. PET‑rCBF with H2(15)O recorded task‑related blood flow while subjects performed face‑matching, location‑matching, and sensorimotor control tasks, with stimuli matched for.

Abstract

The functional dissociation of human extrastriate cortical processing streams for the perception of face identity and location was investigated in healthy men by measuring visual task-related changes in regional cerebral blood flow (rCBF) with positron emission tomography (PET) and H2(15)O. Separate scans were obtained while subjects performed face matching, location matching, or sensorimotor control tasks. The matching tasks used identical stimuli for some scans and stimuli of equivalent visual complexity for others. Face matching was associated with selective rCBF increases in the fusiform gyrus in occipital and occipitotemporal cortex bilaterally and in a right prefrontal area in the inferior frontal gyrus. Location matching was associated with selective rCBF increases in dorsal occipital, superior parietal, and intraparietal sulcus cortex bilaterally and in dorsal right premotor cortex. Decreases in rCBF, relative to the sensorimotor control task, were observed for both matching tasks in auditory, auditory association, somatosensory, and midcingulate cortex. These results suggest that, within a sensory modality, selective attention is associated with increased activity in those cortical areas that process the attended information but is not associated with decreased activity in areas that process unattended visual information. Selective attention to one sensory modality, on the other hand, is associated with decreased activity in cortical areas dedicated to processing input from other sensory modalities. Direct comparison of our results with those from other PET-rCBF studies of extrastriate cortex demonstrates agreement in the localization of cortical areas mediating face and location perception and dissociations between these areas and those mediating the perception of color and motion.