There’s a fascinating new study on involving LSD brain imaging, offering potential insights into consciousness:
MRI scans showed that LSD caused brain activity to become less coordinated in regions that make up what is called the default mode network. The size of the effect was correlated with participants’ ratings of their own ego dissolution, suggesting that this network underlies a stable sense of self.
Another imaging type, magnetoencephalography (MEG), showed that the rhythm of alpha brainwaves weakened under LSD, an effect that was also correlated with ego dissolution. Alpha rhythms are stronger in humans than other animals, and Carhart-Harris thinks it could be a signature of high-level human consciousness.
But LSD also made the brain more unified in its activity, and there was more communication between regions that normally work separately. “The brain is functioning in a simpler way,” says Carhart-Harris.
The results also go some way to explaining how LSD causes dreamlike visual hallucinations. Although the primary visual cortex usually communicates mainly with other parts of the vision system, many other brain areas contributed to the processing of images in volunteers who received LSD.