Cerebral Cortex Advance Access published online on September 16, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp188
Perceptual Expectation Evokes Category-Selective Cortical Activity
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218-2686, USA
Address correspondence to Michael Esterman, Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA. Email: esterman{at}jhu.edu.
Selective visual attention directed to a location (even in the absence of a stimulus) increases activity in the corresponding regions of visual cortex and enhances the speed and accuracy of target perception. We further explored top-down influences on perceptual representations by manipulating observers’ expectations about the category of an upcoming target. Observers viewed a display in which an object (either a face or a house) gradually emerged from a state of phase-scrambled noise; a cue established expectation about the object category. Observers were faster to categorize faces (gender discrimination) or houses (structural discrimination) when the category of the partially scrambled object matched their expectation. Functional magnetic resonance imaging revealed that this expectation was associated with anticipatory increases in category-specific visual cortical activity, even in the absence of object- or category-specific visual information. Expecting a face evoked increased activity in face-selective cortical regions in the fusiform gyrus and superior temporal sulcus. Conversely, expecting a house increased activity in parahippocampal gyrus. These results suggest that visual anticipation facilitates subsequent perception by recruiting, in advance, the same cortical mechanisms as those involved in perception.
Key Words: attention • expectation • fMRI • object perception