Mental imagery of face enhances face-sensitive event-related potentials to ambiguous visual stimuli.

Abstract

Visual mental imagery forms mental representations of visual objects when correspondent stimuli are absent and shares some characters with visual perception. Both the vertex-positive-potential (VPP) and N170 components of event-related potentials (ERPs) to visual stimuli have a remarkable preference to faces. This study investigated whether visual mental imagery modulates the face-sensitive VPP and/or N170 components. The results showed that with significantly larger amplitudes under the face-imagery condition than the house-imagery condition, the VPP and P2 responses, but not the N170 component, were elicited by phase-randomized ambiguous stimuli. Thus, the brain substrates underlying VPP are not completely identical to those underlying N170, and the VPP/P2 manifestation of the category selectivity in imagery probably reflects an integration of top-down mental imagery signals (from the prefrontal cortex) and bottom-up perception signals (from the early visual cortex) in the occipito-temporal cortex where VPP and P2 originate.