PloS one
January 1, 2024
Josh Martin, Fatemeh Gholamali Nezhad, Alice Rueda et al.
2 citations
Ketamine shows rapid antidepressant effects in major depressive disorder, including treatment-resistant depression, but many patients do not respond, and predicting who will benefit is difficult. This study will examine computational mechanisms behind changes in the auditory mismatch negativity response after intravenous ketamine, linking them to neural causes using a hierarchical Bayesian model and a neural mass model. Thirty patients with treatment-resistant depression will undergo EEG recordings during an auditory mismatch negativity task before three of four ketamine infusions, with depression, suicidality, and anxiety assessed throughout. The findings may improve understanding of treatment response and resistance, and model parameters could enable single-patient treatment predictions.
Psychopharmacology
November 5, 2025
Milad Soltanzadeh, Wang Zheng, Shona G. Allohverdi et al.
1 citation
Ketamine and psilocybin, two drugs with therapeutic potential for depression, produce distinct effects on brain electrical activity. Ketamine disrupts the balance between excitation and inhibition in neural circuits, as shown by changes in the aperiodic components of EEG spectra, and reduces beta band activity. Psilocybin also reduces alpha power in similar brain regions but does not affect beta activity or aperiodic components in the same way. These differences reflect their different mechanisms: ketamine blocks NMDA receptors while psilocybin targets serotonin receptors. Ketamine's unique EEG signature supports its role as a model for prodromal psychosis.
bioRxiv (Cold Spring Harbor Laboratory)
November 7, 2025
Gabrielle Allohverdi, Milad Soltanzadeh, André Schmidt et al.
preprint
Ketamine and psilocybin, two hallucinogenic compounds being explored as treatments for major depressive disorder, affect sensory learning in the brain differently. By combining computational modeling with electroencephalography (EEG) data from a prior experiment, researchers analyzed how these drugs alter the brain's processing of unexpected sounds during an auditory task. Ketamine produced a larger reduction in the influence of sensory precision between 207 and 316 milliseconds after a sound, peaking at 277 milliseconds in frontal central brain regions, while psilocybin showed no significant effect in that measure. Both drugs reduced the expression of belief precision between 160 and 184 milliseconds, peaking at 172 milliseconds.
Research Square
September 26, 2024
Shona G. Allohverdi, Milad Soltanzadeh, André Schmidt et al.
Ketamine and psilocybin affect sensory learning in the brain through different neural mechanisms. By combining computational modeling with EEG data from a previous study, researchers analyzed how these drugs alter the brain's processing of prediction errors during an auditory task. Ketamine produced a larger reduction in sensory precision from 207 to 316 milliseconds after sounds, peaking at 277 milliseconds in frontal central brain regions, while psilocybin showed no significant effect on this measure. Both drugs reduced belief precision between 160 to 184 milliseconds, peaking at 172 milliseconds. For higher-level volatility prediction errors, ketamine reduced expression while psilocybin had no effect at 312 milliseconds. These distinct effects could inform tailored therapies for major depressive disorder.