Neural oscillations
Does ketamine model brain activity changes in schizophrenia?
Open access · cc by · source: Europe PMC
Although S-ketamine mimics schizophrenia symptoms, it triggers the opposite effects on brain wave intensity and connectivity compared to patients.
Key findings
Under ketamine, healthy participants showed a large increase in high-frequency gamma oscillations (effect size of d = 0.88) and reduced functional connections between brain regions. Conversely, patients with first-episode psychosis and chronic schizophrenia showed a decrease in gamma oscillations (effect sizes of d = 1.49 and d = 1.07, respectively). Furthermore, patient groups exhibited increased brain connectivity (hyper-connectivity), directly contradicting the effects of ketamine.
Methodology
The researchers measured brain waves in three separate studies during a visual motion-detection task. First, they conducted a crossover study on 14 healthy participants who received either S-ketamine or a placebo. Second, they recorded brain activity from 10 drug-free patients experiencing first-episode psychosis and 10 healthy controls. Finally, they compared 16 patients with chronic schizophrenia to 16 healthy controls.
Limitations
This study utilized relatively small samples across its comparisons, which increases the likelihood of statistical noise and limits generalization. Due to the observational and pharmacological nature of the study, the findings cannot establish a direct causal pathway from chronic NMDA receptor dysfunction to schizophrenia. S-ketamine also affects other neurotransmitters like dopamine and serotonin, meaning the findings cannot isolate NMDA receptor hypofunction as the sole cause of these brain differences.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
MEG can map abnormal functional connectivity and oscillatory abnormalities under pharmacological challenges, revealing that acute ketamine and schizophrenia alter gamma-band power and thalamo-cortical networks in opposing directions.
Evidence for the claim as stated.
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