Category-specific modulation of inferior temporal activity during working memory encoding and maintenance

Findings from neurophysiology have supported the view that visual working memory (WM) relies on modulation of activity in object-selective populations of neurons in inferior temporal cortex. Here, using event-related functional magnetic resonance imaging, we investigated whether similar mechanisms support human visual working memory encoding and maintenance processes. We identified regions in inferior temporal cortex that exhibited category-specific responses during perception of faces (fusiform face area [FFA]) or scenes (parahippocampal place area [PPA]) and investigated whether activity in these regions would be modulated by demands to actively encode and maintain faces and scenes. Results showed that independent of perceptual stimulation, the FFA and PPA exhibited greater encoding- and maintenance-related activity when their favored stimulus was relevant to the recognition task. In contrast, maintenance-related activity in the dorsolateral prefrontal cortex (PFC) was modulated by memory load, regardless of the type of information that was task relevant. These results are consistent with the view that visual working memory encoding and maintenance processes are implemented through modulation of inferior temporal activity by prefrontal cortex. (C) 2004 Elsevier B.V. All rights reserved.