Brain activity related to integrative processes in visual object recognition: bottom-up integration and the modulatory influence of stored knowledge

• Published in: Neuropsychologia Vol. 40; no. 8; pp. 1254 - 1267
• Main Authors: Gerlach, C, Aaside, C.T, Humphreys, G.W, Gade, A, Paulson, O.B, Law, I
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2002; Elsevier Science
• Subjects: Adult; Anatomical correlates of behavior; Attention - physiology; Behavioral psychophysiology; Biological and medical sciences; Brain Mapping; Category-specificity; Discrimination Learning - physiology; Feature integration; Female; Fundamental and applied biological sciences. Psychology; Humans; Magnetic Resonance Imaging; Male; Mental Recall - physiology; Object recognition; Occipital Lobe - diagnostic imaging; Parietal Lobe - physiology; Pattern Recognition, Visual - physiology; Perceptual Closure - physiology; PET; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reference Values; Structural knowledge; Temporal Lobe - diagnostic imaging; Tomography, Emission-Computed; Category-specificity; Structural knowledge; Feature integration; Object recognition; PET; Radionuclide study; Temporal lobe; Visual cortex; Information integration; Central nervous system; Cognition; Occipital lobe; Perception; Object; Categorization; Recognition; Brain (vertebrata); Emission tomography
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/S0028-3932(01)00222-6

We report evidence from a PET activation study that the inferior occipital gyri (likely to include area V2) and the posterior parts of the fusiform and inferior temporal gyri are involved in the integration of visual elements into perceptual wholes (single objects). Of these areas, the fusiform and inferior temporal gyri were more activated by tasks with recognizable stimuli than by tasks with unrecognizable stimuli. We propose that the posterior parts of the fusiform and inferior temporal gyri, compared with the inferior occipital gyri, are involved in higher level integration, due to the involvement of re-entrant activation from stored structural knowledge. Evidence in favor of this interpretation comes from the additional finding that activation of the anterior part of the left fusiform gyrus and a more anterior part of the right inferior temporal gyrus, areas previously associated with access to stored structural knowledge, was found with recognizable stimuli, but not with unrecognizable stimuli. This latter finding also indicates: (i) that subjects may not refrain from (automatically) identifying objects even if they only have to attend to the objects’ global shape, and (ii) that perceptual and memorial processes can be dissociated on both functional and anatomical grounds. No evidence was obtained for the involvement of the parietal lobes in the integration of single objects.