Top-down processing mediated by interareal synchronization
Abstract
Perception and cortical responses are not only driven "bottom-up" by the external stimulus but are altered by internal constraints such as expectancy or the current behavioral goal. To investigate neurophysiological mechanisms of such top-down effects, we analyzed the temporal interactions of neurons on different levels of the cortical hierarchy during perception of stimuli with varying behavioral significance. We found that interareal interactions in a middle-frequency range (θ and α; 4-12 Hz) strongly depend on the associated behavior, with a phase relationship and a layer specificity indicating a top-down-directed interaction. For novel unexpected stimuli, presumably processed in a feed-forward fashion, no such interactions occurred but high-frequency interactions (γ; 20-100 Hz) were observed. Thus corticocortical synchronization reflects the internal state of the animal and may mediate top-down processes.
- Publication:
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Proceedings of the National Academy of Science
- Pub Date:
- December 2000
- DOI:
- 10.1073/pnas.97.26.14748
- Bibcode:
- 2000PNAS...9714748V
- Keywords:
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- Neurobiology