First synthesized by Albert Hofmann, a researcher with the Swiss chemical company Sandoz, lysergic acid diethylamide (LSD) is a hallucinogenic drug that was initially used by the CIA to conduct clandestine experiments, as per History. Over time, LSD became a counter-cultural symbol, commonly associated with the 1960’s hippie culture.

Although popularly used to induce hallucinogenic experiences or “trips,” LSD is known for its healing properties. In recent years, as the Independent reported, numerous scientific studies have shown that psychedelic drugs like LSD stimulate the growth of new branches and connections between brain cells. This could help address various mental conditions like addiction and depression.

A new neuroimaging study published in Proceedings of the National Academy of Sciences shows that LSD allows more information to flood into the brain by altering activity in a small section of the midbrain known as thalamus.

Authored by Katrin H. Preller, Peter Zeidman, Karl J. Friston Philipp Stämpfli, Adeel Razi, and Franz X. Vollenweider of the University of Zurich, “Effective connectivity changes in LSD-induced altered states of consciousness in humans” adds to the growing body of work pertaining to the potentially therapeutic properties of LSD.

“Using cutting-edge neuroimaging methods we investigated directed connectivity between cortico–striato–thalamo-cortical (CSTC) regions after administration of LSD together with the specific role of the serotonin 2A receptor,” University of Zurich researchers wrote.

For the study, the researchers recruited 25 healthy individuals, 19 males and six females, ages 20-34.

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To prove their hypothesis, the scientists relied on the thalamic filter model which suggests that the benefits of drugs such as LSD result from decreasing information filtering in the thalamus, allowing more information to flow through the brain.

The researchers characterized changes in effective connectivity between cortico-striato-thalamo-cortical (CSTC) regions after administration of LSD, and after pre-treatment with a serotonin 2A receptor Katenserin.

The study was randomized and placebo-controlled.

After analyzing fMRI data, University of Zurich researchers confirmed their hypothesis, finding that LSD altered the connectivity between brain regions in the CSTC loop. Data showed a noticeable increase in connectivity between the thalamus and a number of areas in the cortex.

“We tested a model that tries to explain how psychedelics work in the brain based on animal studies and that had been around for about 20 years. We showed that this model holds mostly true in humans: The thalamus, which is usually filtering information, sends more information to certain areas in the cortex,” the researchers explained in a statement supplied to PsyPost.

This shows why psychedelic drugs induce the powerful feelings drug users report, and demonstrates how important the connection between certain cortical areas and the thalamus is, the researchers said.

The researchers also found that ketanserin, a serotonin 2A receptor antagonist, inhibited the hallucinogenic effects of the drug.

These results could, according to the researchers, be important for the development of new therapeutics for treating depression, schizophrenia, obsessive-compulsive and other disorders.

“Together, these results advance our mechanistic understanding of the action of psychedelics in health and disease,” they concluded.