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The representation of objects in the human occipital and temporal cortex
A Ishai1, L G Ungerleider, A Martin
1Laboratory of Brain and Cognition, NIMH, National Institutes of Health, Bethesda, MD 20892, USA. alumit@ln.nimh.nih.gov
Journal of Cognitive Neuroscience
|August 17, 2001
Summary
Brain imaging reveals distributed object representations across the ventral visual pathway, not just localized areas. Object form information is processed broadly in both occipital and temporal cortices.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Perception
Background:
- Previous functional magnetic resonance imaging (fMRI) studies identified specialized regions in the ventral temporal cortex for processing specific object categories like faces, houses, and chairs.
- These findings suggested a degree of functional localization within the ventral visual pathway.
Purpose of the Study:
- To investigate whether similar category-specific activation patterns extend to the ventral occipital cortex.
- To explore the extent and nature of object representation across the broader ventral visual pathway, including both occipital and temporal regions.
- To determine if object representations are localized or distributed across cortical areas.
Main Methods:
- Utilized functional magnetic resonance imaging (fMRI) to measure brain activity.
- Examined differential patterns of activation in response to various object categories (faces, houses, chairs).
- Assessed responses across different cortical regions, including ventral occipital cortex, dorsal occipital cortex, and superior temporal sulcus, and across different tasks and presentation formats.
Main Results:
- Differential activation patterns, similar to those in the ventral temporal cortex, were observed in bilateral ventral occipital cortex regions.
- Category-related responses were also detected in the dorsal occipital cortex and superior temporal sulcus.
- Each object category elicited a unique differential response pattern across a wide cortical expanse, rather than activating discrete, segregated areas.
- These distributed response patterns remained consistent across passive viewing and delayed matching tasks, and across photographs and line drawings.
Conclusions:
- Object representation in the ventral visual pathway is not confined to small, highly selective cortical areas but is a distributed process involving information about object form.
- The ventral visual pathway, encompassing both occipital and temporal regions, exhibits a distributed system for object representation.
- The neural representation of faces appears to be less spatially extensive within this distributed system compared to non-face objects.