Those famous musicians and artists who touted psychedelic drugs as a key component of their creativity may have been onto something — at least when it comes to the diversity of signals going off in the brain.
Researchers at the University of Sussex Sackler Centre for Consciousness Science
have found a distinctive brain signature for the psychedelic state of consciousness. Subjects using one of three different psychedelic drugs showed an increase in brain signal diversity compared with when they were in a normal waking state. Brain signal diversity is one measure of the complexity of brain activity.
“This finding shows that the brain on psychedelics behaves very differently from normal,” said Anil Seth
, co-director of the Sackler Centre and a senior fellow in CIFAR’s Azrieli Program in Brain, Mind & Consciousness
. “The brain on psychedelics is less predictable, more random and more diverse than in the normal waking state.”
The study is the first to show an increased signal diversity compared with someone who is in an “awake and aware” state. In the past, research has only shown decreased signal diversity during non-dreaming sleep and in people who are under anesthesia or suffering from disorders of consciousness such as coma or the vegetative state.
Seth and his colleagues Michael Schartner and Adam Barrett looked at MEG (magnetoencephalography) data from previous research done at Imperial College London and the University of Cardiff with healthy volunteers that had taken LSD, psilocybin or ketamine. They analyzed the data using a number of existing mathematical measures of signal diversity to help them understand why psychedelic drugs create their particular conscious experience.
In addition to seeing an increase in neural signal activity across the brain in subjects under the influence of these drugs, the study also found a correlation between certain changes in signal diversity and people’s feelings of “ego dissolution” and increased vividness of imagination.
Seth says these results push forward theoretical models of consciousness by showing that a measure of conscious level (how conscious someone is) is also sensitive to differences in conscious content (what someone is conscious of, or experiences). The relationship between these two components of consciousness is an ongoing debate in the science of consciousness and is the focus of work by fellow Azrieli Program in Brain, Mind & Consciousness member Tim Bayne
Seth and the team hope to conduct further research to better understand how specific neural interactions relate to these psychedelic experiences, with the overall aim of developing a better understanding of how our brain creates our specific feelings of being conscious.
Building on these results could also contribute to a growing body of research on how and when psychedelics could be used for therapeutic treatment of psychiatric disorders like depression.