According to a study published in the International Journal of Neuropsychopharmacology in 2018, specific brain waves are related to the anti-anxiety effects of ketamine. The brain waves involved in this function are called theta waves, found in the right frontal area of the brain. Ketamine can treat a wide variety of neurotic disorders, such as depression, generalized anxiety disorder, and PTSD, but researchers do not conclusively understand how ketamine works to relieve the symptoms of these disorders.
To better understand the therapeutic effects of ketamine, researchers studied the brain activity of patients given ketamine. Patients with generalized anxiety disorder and/or social anxiety disorder were administered ketamine and hooked up to a monitor measuring electrical brain activity (EEG). Ketamine affected the power of the brain waves by increasing the fast waves and decreasing the slow waves. However, only a single frequency band was related to therapeutic effects—the theta waves.
Human consciousness is believed to be related to neurons firing synchronously in various frequencies. Theta waves are in the 4 to 7 hertz rhythms. During meditation, theta waves predominated and were most abundant in the frontal and middle parts of the brain. Professor Jim Lagopoulos states, "These types of waves likely originate from a relaxed attention that monitors our inner experiences. Here lies a significant difference between meditation and relaxing without any specific technique. Previous studies have shown that theta waves indicate deep relaxation and occur more frequently in highly experienced meditation practitioners. When we measure mental calm, these regions signal to lower parts of the brain, inducing the physical relaxation response that occurs during meditation."
So ketamine infusions seems to put the brain into a similar state that highly experienced meditators can achieve allowing for a calm, relaxed state of mind.
In conclusion, the anti-anxiety relief of ketamine may related to a very specific portion of electrical brain activity. This finding combined with the knowledge that ketamine blocks the NMDA glutamate receptor helps researchers understand how ketamine affects the brain. This preliminary study paves the way for future research on brain studies and ketamine.