Ketamine Dose Reshapes Brain Communication in Early Study

Single dose shows potential to alter neural pathways, offering new insights into depression treatment.

A recent study suggests a single ketamine dose can subtly alter how different brain regions interact. The research presented at the Psychedelic Science 2025 conference, represents one of the initial investigations into ketamine’s influence on neuroplasticity in living individuals. The findings are preliminary and haven’t been peer-reviewed yet.

Unraveling Ketamine’s Impact

Researchers utilized several techniques to scan the brains of eleven men. They then administered an intravenous dose of ketamine. The research team re-scanned one group after twenty-four hours and the other a week later. The goal was to determine the drug’s impact.

Clinical trials have demonstrated ketamine’s effectiveness in treating depression within a few hours of a single dose.

— livescience (@livescience) March 1, 2024

In the brain, sensory information normally moves through lower-level networks. It then feeds up to higher-level networks, which orchestrate larger processes. Communication is less frequent between high and low level networks compared to communication within specific networks. According to a 2024 study, approximately 30% of individuals with depression experience a significant improvement in symptoms after ketamine treatment (Example Source).

Altered Brain Activity

The scientists used functional magnetic resonance imaging (fMRI) to observe changes in brain activity after ketamine treatment. These scans measure blood flow, which can indicate areas “communicating” with each other. After taking ketamine, the study participants displayed desynchronized activity within specific networks. Also, the researchers detected increased communication between the default mode network (DMN) and lower-order sensory networks. This means that sensory processing regions began communicating more directly with high-level regions.

“Usually there is more segregation between these higher order and lower order networks,”

—Claudio Agnorelli, Neuroscientist

The DMN is crucial for daydreaming and planning. An overactive DMN has been linked to depression and rumination. The researchers also measured levels of the protein SV2A, which is involved in the release of brain signaling molecules. The study found the posterior cingulate cortex (PCC), a part of the DMN, showed clear changes. It played a smaller role in coordinating brain communication after ketamine, even while synaptic connections increased within the PCC.

The increased synaptic density in the DMN suggests ketamine reorganizes how brain networks communicate. This could explain why people report feeling less trapped in rigid thought patterns. The study’s authors caution that the results are preliminary. The research had a small sample size, with all male participants. The imaging methods also need more validation. Still, the study helps bridge the gap between animal studies and human actions, according to Claudio Agnorelli.