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LSD changes consciousness by reorganizing human brain networks

LSD changes consciousness by reorganizing human brain networks

LSD is known to cause changes in consciousness, including “ego-dissolution”, or a loss of the sense of self. Despite a detailed knowledge of the action of LSD at specific serotonin receptors, it has not been understood how this these pharmacological effects can translate into such a profound effect on consciousness.

Today, a new report presented at the annual meeting of the American College of Neuropsychopharmacology in Hollywood, Florida, provides evidence to show that LSD reduces connectivity within brain networks, or the extent to which nerve cells or neurons within a network fire in synchrony. LSD also seems to reduce the extent to which separate brain networks remain distinct in their patterns or synchronization of firing.

Overall, LSD interferes with the patterns of activation in the different brain networks that underlie human thought and behavior.

In the new study, Dr. Robin Carhart-Harris and his colleagues at Imperial College London did sequential brain scans of 20 healthy volunteers over 6 hours, using functional magnetic resonance imaging (fMRI), which maps brain activity by detecting changes in blood flow, and magnetoencephalography (MEG), a technique that images brain function by recording magnetic fields produced by electrical currents occurring in the brain. Using fMRI, the investigators showed that LSD led to a more chaotic brain state not entirely dissimilar to what is seen in the prodromal phase of psychosis.

Specifically, neurons that were supposed to fire together within a network fell out of synchrony, while networks that are normally distinct started to overlap in their connectivity patterns. Dr. Carhart-Harris also found increases in blood flow in the visual cortex at the back of the brain, which might explain the visual hallucinations and distortions so common in LSD intoxication. MEG also showed a change in natural brain oscillations, specifically a decrease in alpha waves across the brain. The MEG changes were highly correlated with visual hallucinations, suggesting that under the influence of LSD, the visual system is tethered more to the internal than to the external world.

Dr. Carhart-Harris suggests that,

“With better assessment tools available today than in the 1950’s and 1960’s, it may be possible to evaluate potential uses of LSD as a treatment for addiction and other disorders, such as treatment-resistant depression – which we are currently investigating with a similar drug to LSD.”

LSD also may provide a useful human model of psychosis, as it leads to changes in brain network behavior that shows overlap with the early phase of psychosis

Lebedev, A., Lövdén, M., Rosenthal, G., Feilding, A., Nutt, D., & Carhart-Harris, R. (2015). Finding the self by losing the self: Neural correlates of ego-dissolution under psilocybin Human Brain Mapping, 36 (8), 3137-3153 DOI: 10.1002/hbm.22833


One response

  1. Devin Thomas

    LSD is a bad idea in my opinion. It can change the way you think and act forever. It has been proven to have no positive outcomes. Some people experienced what are known as “bad trips”, and a lot of times these led to suicidal attempts or people actually killing themselves while on acid. LSDs activation of post synaptic 5-HT2a receptros increases the activity of both glutamate and GABA neurons. Enhanced glutamate release increases sensory signals to the cerebral cortex. At the same time, GABA release decreases spontaneous activity in the locus coeruleus, causing greater refinement of sensory signals sent to the cerebral cortex. LSD causes normally suppressed sensory information from the locus coeruleus to become more refined and salient.

    December 10, 2015 at 7:08 pm

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