For the first time in history, the effects of LSD on the human brain have been revealed using cutting-edge brain imaging technology. Conducted by the Beckley/Imperial Research Programme, this landmark study provides a window into the mechanisms behind many of the subjective experiences associated with LSD, such as visual hallucinations and a sense of ‘ego-dissolution’, and offers invaluable insights into how these effects may be harnessed for therapeutic means.
Published in the Proceedings of the National Academy of Sciences (PNAS), the findings show how the drug decreases communication between the brain regions that make up the Default Mode Network (DMN), a collection of hub centres that work together to control and repress consciousness. Like the conductor in an orchestra, the DMN polices the amount of sensory information that enters our sphere of awareness, and has been described as the neural correlate of the ‘ego’.
Yet the DMN disintegrates under LSD, allowing for a magnificent increase in communication between brain networks that are normally highly segregated. This produces a more integrated pattern of connectivity throughout the entire brain, which may be associated with more fluid modes of cognition. Results of the study show that the magnitude of this effect is directly correlated to the the strength of the subjective experience of ‘ego-dissolution’ and feeling of oneness and unity. This could have major implications for LSD-assisted psychotherapy, as it indicates how the drug allows patients to break free from the rigid modes of cognition and thought that underlie hard-to-treat conditions such as depression and addiction.
Dr. Robin Carhart-Harris of the Beckley/Imperial Research Programme explained how “this effect underlies the profound altered state of consciousness that people often describe during an LSD experience. It is also related to what people sometimes call ‘ego-dissolution’, which means the normal sense of self is broken down and replaced by a sense of reconnection with themselves, others and the natural world. This experience is sometimes framed in a religious or spiritual way – and seems to be associated with improvements in well-being after the drug’s effects have subsided.”
To conduct the research, the team recruited 20 volunteers, each of whom was then administered either 75 micrograms of LSD or placebo before having their brains scanned using various techniques including fMRI and magnetoencephalography (MEG).
The resulting images showed how the brain’s visual cortex, which normally receives and processes information from the eyes, begins to communicate with a wide range of other brain regions under the effects of LSD. This means that many brain regions that aren’t normally involved in vision suddenly contribute to visual processing, which explains why people tend to experience dreamlike hallucinations when they use the drug.
“We observed brain changes under LSD that suggested our volunteers were ‘seeing with their eyes shut’ – albeit they were seeing things from their imagination rather than from the outside world. We saw that many more areas of the brain than normal were contributing to visual processing under LSD – even though the volunteers’ eyes were closed. Furthermore, the size of this effect correlated with volunteers’ ratings of complex, dreamlike visions,” explained Carhart-Harris.
While there’s plenty more work to be done before the effects of LSD are fully understood, this research marks a watershed moment in the history of psychedelic science, illuminated key mechanisms via which psychedelics may transiently alter normal brain function and exert their therapeutic action.
Amanda Feilding, founder and co-director of the Beckley/Imperial Research Programme, summed up the significance of this research by stating that “we are finally unveiling the brain mechanisms underlying the potential of LSD, not only to heal, but also to deepen our understanding of consciousness itself.”
The results of this study were first revealed to the world at the prestigious Royal Society in London, where Amanda Feilding and co-researchers Professor David Nutt and Dr Robin Carhart-Harris addressed the global media as well as members of the public about our groundbreaking findings.
Authors: Carhart-Harris RL, Muthukumaraswamy S, Roseman L, Kaelen M, Droog W, Murphy K, Tagliazucchi E, Schenberg EE, Nest T, Orban C, Leech R, Williams LT, Williams TM, Bolstridge M, Sessa B, McGonigle J, Sereno MI, Nichols D, Hellyer PJ, Hobden P, Evans J, Singh KD, Wise RG, Curran HV, Feilding A, Nutt DJ.
Lysergic acid diethylamide (LSD) is the prototypical psychedelic drug, but its effects on the human brain have never been studied before with modern neuroimaging. Here, three complementary neuroimaging techniques: arterial spin labeling (ASL), blood oxygen level-dependent (BOLD) measures, and magnetoencephalography (MEG), implemented during resting state conditions, revealed marked changes in brain activity afterLSD that correlated strongly with its characteristic psychological effects. Increased visual cortex cerebral blood flow (CBF), decreased visual cortex alpha power, and a greatly expanded primary visual cortex (V1) functional connectivity profile correlated strongly with ratings of visual hallucinations, implying that intrinsic brain activity exerts greater influence on visual processing in the psychedelic state, thereby defining its hallucinatory quality. LSD‘s marked effects on the visual cortex did not significantly correlate with the drug’s other characteristic effects on consciousness, however. Rather, decreased connectivity between the parahippocampus and retrosplenial cortex (RSC) correlated strongly with ratings of “ego-dissolution” and “altered meaning,” implying the importance of this particular circuit for the maintenance of “self” or “ego” and its processing of “meaning.” Strong relationships were also found between the different imaging metrics, enabling firmer inferences to be made about their functional significance. This uniquely comprehensive examination of the LSD state represents an important advance in scientific research with psychedelic drugs at a time of growing interest in their scientific and therapeutic value. The present results contribute important new insights into the characteristic hallucinatory and consciousness-altering properties of psychedelics that inform on how they can model certain pathological states and potentially treat others.
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