Varieties of perceptual instability and their neural correlates.
We report experiments designed to learn whether different kinds of perceptually unstable visual images engage different neural mechanisms. 21 subjects viewed two types of bi-stable images while we scanned the activity in their brains with functional magnetic resonance imaging (fMRI); in one (intra-categorical type) the two percepts remained within the same category (e.g. face-face) while in the other (cross-categorical type) they crossed categorical boundaries (e.g. face-body). The results showed that cross- and intra-categorical reversals share a common reversal-related neural circuitry, which includes fronto-parietal cortex and primary visual cortex (area V1). Cross-categorical reversals alone engaged additional areas, notably anterior cingulate cortex and superior temporal gyrus, which have been posited to be involved in conflict resolution.
Wellcome Laboratory of Neurobiology and Wellcome Department of Imaging Neuroscience, University College London, Gower Street, London WC1E 6BT, United Kingdom. Electronic address: t.ishizu@ucl.ac.uk.
Tomohiro
T
Ishizu
Wellcome Laboratory of Neurobiology and Wellcome Department of Imaging Neuroscience, University College London, Gower Street, London WC1E 6BT, United Kingdom. Electronic address: zeki.pa@ucl.ac.uk.
Semir
S
Zeki
D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D003220:Conflict, Psychological; D017352:Echo-Planar Imaging; D005145:Face; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D010296:Parietal Lobe / Q000502:physiology; D010775:Photic Stimulation; D011578:Psycholinguistics; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
Ambiguity; Anterior cingulate cortex; Conflict resolution; Cross categorical boundary; Perceptual reversal