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Updated: Jun 7, 2026
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Generation of Local CA1 γ Oscillations by Tetanic Stimulation
Published on: August 14, 2015
NMDA receptor hypofunction phase couples independent γ-oscillations in the rat visual cortex
Himashi Anver1, Peter D Ward, Andor Magony
1Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom.
Summary
Ketamine and PCP disrupt brain oscillations by slowing high-frequency gamma waves (HFγ) to match low-frequency gamma waves (LFγ). This synchrony may explain psychosis symptoms and suggests accelerating HFγ could be an antipsychotic target.
Area of Science:
- Neuroscience
- Psychopharmacology
Background:
- Hallucinations in psychosis are linked to N-methyl-D-aspartic acid (NMDA) receptor antagonist effects and gamma-frequency band hypersynchronization.
- The distinct roles of low-frequency gamma (LFγ) and high-frequency gamma (HFγ) oscillations in perception and how NMDA receptor hypofunction impacts them remain unclear.
Purpose of the Study:
- To investigate the effects of ketamine and phencyclidine (PCP) on the interaction between LFγ and HFγ in the rat visual cortex.
- To explore the potential mechanisms linking NMDA receptor hypofunction to altered neural synchrony and perceptual distortions.
Main Methods:
- Electrophysiological recordings in rat visual cortex slices.
- Induction of LFγ and HFγ using kainate and carbachol.
- Administration of ketamine, PCP, and other NMDA receptor modulators to assess effects on γ-oscillations.
Main Results:
- Ketamine and PCP selectively decelerated HFγ, causing phase coupling with LFγ and entraining pyramidal neuron firing.
- NMDA receptor hypofunction mimicked this deceleration, while NMDA receptor activation accelerated HFγ.
- Aberrant cross-layer synchronization between LFγ and HFγ networks was observed under NMDA receptor hypofunction conditions.
Conclusions:
- NMDA receptor hypofunction-induced phase coupling of γ-oscillations may distort perception by disrupting normal information processing.
- Targeting HFγ acceleration presents a potential therapeutic strategy for psychosis, addressing the underlying neural synchrony.
