Advances and challenges in neuroimaging studies on the effects of serotonergic hallucinogens: Contributions of the resting brain.

Summary

Hallucinogenic drugs like psilocybin, LSD, and ayahuasca show consistent effects on the resting brain, including decreased cerebral blood flow and increased global functional connectivity in specific brain regions. However, LSD uniquely reduces functional connectivity within certain networks. The findings are complicated by small sample sizes and potential biases, indicating that while neuroimaging may help clarify the neuronal effects of hallucinogens, results across studies remain heterogeneous.

Study at a glance

Abstract

The effects of hallucinogenic drugs on the human brain have been studied since the earliest days of neuroimaging in the 1990s. However, approaches are often hard to compare and results are heterogeneous. In this chapter, we summarize studies investigating the effects of hallucinogens on the resting brain, with a special emphasis on replicability and limitations. In previous studies, similarities were observed between psilocybin, LSD, and ayahuasca, with respect to decreases in cerebral blood flow and increases in global functional connectivity in the precuneus and thalamus. Additionally, LSD consistently decreased functional connectivity within distinct resting state networks. Little convergence was observed for connectivity between networks and for blood flow in other brain regions. Although these studies are limited by small sample sizes and might be biased by unspecific drug effects on physiological parameters and the vascular system, current results indicate that neuroimaging could be a useful tool to elucidate the neuronal correlates of hallucinogenic effects.

Tags