Here is an overview of the expected brainwave changes with therapeutic ketamine administration, with cited sources:
At anesthetic doses, ketamine is known to induce brainwave changes, including [1]:
- Reduction in alpha waves (8-13 Hz) associated with quiet wakefulness
- Increase in theta waves (4-7 Hz) indicating deep relaxation or early stages of sleep
- Increase in delta waves (0.5-4 Hz) associated with deep sleep
- Increase in high-frequency beta waves (13-30 Hz)
However, at subanesthetic doses used for depression, ketamine appears to increase higher frequency gamma oscillations (30-80 Hz) in cortical regions [2].
Gamma waves involve cognitive processing like attention, working memory, and perceptual binding of stimuli [3]. This effect on gamma power is associated with ketamine’s rapid antidepressant effects [4].
In depressed patients, a single IV ketamine infusion can boost frontal gamma power within hours, lasting up to 7 days [5]. This heightened cortical excitability and plasticity allows the “re-wiring” of rigid negative thinking patterns in depression.
Unlike anesthetic doses, therapeutic ketamine enhances fast gamma oscillations implicated in conscious cognitive processing. This may support its ability to rapidly “reset” neural circuits and ameliorate psychiatric symptoms like anhedonia, rumination, and hopelessness.
[1] Plourde G, Baribeau J, Bonhomme V. Ketamine increases the amplitude of the 40-Hz auditory steady-state response in humans. Br J Anaesth. 1997;78(5):524-529. doi:10.1093/bja/78.5.524
[2] Abdallah CG, Averill LA, Collins KA, et al. Ketamine Treatment and Global Brain Connectivity in Major Depression. Neuropsychopharmacology. 2017;42(6):1210-1219. doi:10.1038/npp.2016.197
[3] Uhlhaas PJ, Singer W. Neural synchrony in brain disorders: relevance for cognitive dysfunctions and pathophysiology. Neuron. 2006;52(1):155-168. doi:10.1016/j.neuron.2006.09.020
[4] Cornwell BR, Salvadore G, Furey M, et al. Synaptic potentiation is critical for rapid antidepressant response to ketamine in treatment-resistant major depression. Biol Psychiatry. 2012;72(7):555-561. doi:10.1016/j.biopsych.2012.03.029
[5] Duncan WC Jr, Selter J, Brutsche N, Nezam Zadeh H, Sarasso S, Zarate CA Jr. Baseline Gamma Power During Auditory Steady-State Stimulation in Major Depressive Disorder and Healthy Control Subjects: Associations With Baseline Symptoms and Ketamine Treatment Outcome. Biol Psychiatry Cogn Neurosci Neuroimaging. 2019 ;4(2):191-200. doi:10.1016/j.bpsc.2018.11.004