期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 103, 期 2, 页码 449-454出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0507062103
关键词
feedback; object recognition; orbitofrontal cortex; visual cortex; low spatial frequency
资金
- NCRR NIH HHS [5P41RR014075, P41 RR014075] Funding Source: Medline
- NINDS NIH HHS [R01 NS050615, NS18741, R01 NS044319, R01 NS018741, NS44319, NS50615] Funding Source: Medline
Cortical analysis related to visual object recognition is traditionally thought to propagate serially along a bottom-up hierarchy of ventral areas. Recent proposals gradually promote the role of top-down processing in recognition, but how such facilitation is triggered remains a puzzle. We tested a specific model, proposing that low spatial frequencies facilitate visual object recognition by initiating top-down processes projected from orbitofrontal to visual cortex. The present study combined magnetoencephalography, which has superior temporal resolution, functional magnetic resonance imaging, and a behavioral task that yields successful recognition with stimulus repetitions. Object recognition elicited differential activity that developed in the left orbitofrontal cortex 50 ms earlier than it did in recognition-related areas in the temporal cortex. This early orbitofrontal activity was directly modulated by the presence of low spatial frequencies in the image. Taken together, the dynamics we revealed provide strong support for the proposal of how top-down facilitation of object recognition is initiated, and our observations are used to derive predictions for future research.
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