LSD and Brain Imaging

Nature: "Brain scans reveal how LSD affects consciousness"

We found that under LSD, compared to placebo, disparate regions in the brain communicate with each other when they don’t normally do so. In particular, the visual cortex increases its communication with other areas of the brain, which helps explain the vivid and complex hallucinations experienced under LSD, and the emotional flavour they can take.

On the other hand, within some important brain networks, such as the neuronal networks that normally fire together when the brain is at rest, sometimes called the ‘default mode network’, we saw reduced blood flow — something we’ve also seen with psilocybin — and that neurons that normally fire together lost synchronization. That correlated with our volunteers reporting a disintegration of their sense of self, or ego. This known effect is called ‘ego dissolution': the sense that you are less a singular entity, and more melded with people and things around you. We showed that this could be experienced independently of the hallucinatory effects — the two don’t necessarily go together...