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Theta, but Not Gamma Oscillations in Area V4 Depend on Input from Primary Visual Cortex
Ricardo Kienitz1, Michele A Cox2, Kacie Dougherty3
1Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, 60528 Frankfurt am Main, Germany; Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; Epilepsy Center Frankfurt Rhine-Main, Center of Neurology and Neurosurgery, Goethe University, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany.
Current Biology : CB
|December 5, 2020
Summary
Neural oscillations theta and gamma were studied in macaque monkeys. V1 lesions revealed theta oscillations are crucial for feedforward processing, while gamma oscillations are less dependent on this pathway.
Area of Science:
- Neuroscience
- Visual Cortex Research
- Neural Oscillations
Background:
- Theta (3-9 Hz) and gamma (30-100 Hz) oscillations are observed across cortical areas and cognitive tasks.
- In the visual system, these rhythms in V1 and V4 are linked to perceptual reaction times.
- Previous studies suggested both theta and gamma oscillations reflect feedforward sensory processing from V1 to V4.
Purpose of the Study:
- To experimentally assess the role of theta and gamma oscillations in feedforward processing.
- To investigate the impact of V1 lesions on V1 and V4 oscillations in macaque monkeys.
- To differentiate the roles of theta and gamma oscillations in visual processing.
Main Methods:
- Recorded neural activity using multi-electrode arrays in V1 and V4 of macaque monkeys.
- Induced oscillations by presenting a visual contour illusion.
- Performed V1 lesions to assess the impact on V4 oscillations.
- Conducted laminar analysis in V1.
Main Results:
- Both theta and gamma oscillations were elicited in V1 and V4 with intact cortex and showed phase-to-amplitude coupling.
- In V1, theta and gamma oscillations were primarily found in supragranular layers.
- V1 lesioning eliminated V4 theta oscillations but only delayed V4 gamma oscillations, with little effect on power.
Conclusions:
- Theta oscillations are more tightly associated with feedforward sensory processing than gamma oscillations.
- The findings challenge the proposed role of gamma oscillations as a primary feedforward mechanism.
- Dissociation in V4 suggests distinct functional roles for theta and gamma rhythms in visual information flow.
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