Neuron
Volume 85, Issue 2, 21 January 2015, Pages 390-401
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Article
Visual Areas Exert Feedforward and Feedback Influences through Distinct Frequency Channels

https://doi.org/10.1016/j.neuron.2014.12.018Get rights and content
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Highlights

  • Influences among visual areas are dominated by theta, beta, and gamma-band rhythms

  • Theta and gamma rhythms subserve feedforward, the beta rhythm feedback influences

  • Frequency-specific directed influences constitute a functional hierarchy

  • Functional hierarchy changes with behavioral context, especially for frontal areas

Summary

Visual cortical areas subserve cognitive functions by interacting in both feedforward and feedback directions. While feedforward influences convey sensory signals, feedback influences modulate feedforward signaling according to the current behavioral context. We investigated whether these interareal influences are subserved differentially by rhythmic synchronization. We correlated frequency-specific directed influences among 28 pairs of visual areas with anatomical metrics of the feedforward or feedback character of the respective interareal projections. This revealed that in the primate visual system, feedforward influences are carried by theta-band (∼4 Hz) and gamma-band (∼60–80 Hz) synchronization, and feedback influences by beta-band (∼14–18 Hz) synchronization. The functional directed influences constrain a functional hierarchy similar to the anatomical hierarchy, but exhibiting task-dependent dynamic changes in particular with regard to the hierarchical positions of frontal areas. Our results demonstrate that feedforward and feedback signaling use distinct frequency channels, suggesting that they subserve differential communication requirements.

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Present address: Max Planck Institute for Psycholinguistics, Wundtlaan 1, 6525 XD Nijmegen, Netherlands