| Summary: | A study investigated whether working memory (WM) is mediated by sustained feature-selective activation patterns in cortical regions that process the necessary sensory information. Based on functional magnetic resonance imaging, findings indicated that key sensory regions such as primary visual cortex (V1) bore little evidence of sustained increases in mean activation during a WM delay period, although such amplitude increases have generally been used to determine whether a brain region has a function in online maintenance. However, findings from a multivoxel pattern analysis of delay-period activity demonstrated a sustained pattern of V1 activation, which represented only the intentionally stored feature of a multifeature object. Furthermore, findings showed the qualitative similarity between the pattern of delay activity and that observed during the discrimination of sensory stimuli, indicating that WM representations in V1 are reasonable “copies” of those induced during pure sensory processing.
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