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Updated: Apr 25, 2026
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A Large Lateral Craniotomy Procedure for Mesoscale Wide-field Optical Imaging of Brain Activity
Published on: May 7, 2017
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Beta oscillation dynamics in extrastriate cortex after removal of primary visual cortex.
Joscha T Schmiedt1, Alexander Maier2, Pascal Fries3
1Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528 Frankfurt, Germany.
Summary
Primary visual cortex (V1) input normally suppresses beta oscillations in visual area V4. Removing V1 input surprisingly reversed this, causing beta increases during visual stimulation, revealing V1
Area of Science:
- Neuroscience
- Visual Cortex Research
- Brain Oscillations
Background:
- Visual cortex exhibits distinct spectral patterns: low-frequency beta oscillations dominate before stimuli, replaced by high-frequency gamma during stimulation.
- The origins of beta oscillations and their suppression during visual input remain incompletely understood.
Purpose of the Study:
- To investigate the role of ascending input from primary visual cortex (V1) in modulating beta oscillation dynamics in extrastriate visual area V4.
- To elucidate the mechanisms underlying beta oscillation generation and suppression in the visual cortex.
Main Methods:
- Local field potential (LFP) activity was recorded in V4 of behaving monkeys before and after V1 resection.
- Analysis focused on changes in beta (12-20 Hz) and gamma (>30 Hz) LFP power spectra in response to visual stimuli.
Main Results:
- V1 resection significantly reduced visually induced gamma LFP activity in V4, confirming previous findings.
- Spontaneous beta oscillations in V4 were largely unaffected by the V1 lesion.
- A surprising, permanent reversal of beta suppression was observed: visual stimuli increased beta magnitude in V4, particularly for moving stimuli in lesioned areas.
Conclusions:
- Preserved spontaneous beta oscillations suggest a generation mechanism independent of the geniculostriate pathway.
- The reversed beta response indicates that V1 input normally suppresses beta activity, and its absence leads to stimulus-driven beta potentiation.
- Direct thalamo-extrastriate projections contribute to visual information processing and beta activity modulation in V4.
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