When you think of altered states of consciousness (ASC), what are some of the first things that come to mind? If you’re like most of us — and not a neuroscientist or anthropologist — you’ll probably think of 1960s counterculture; of school buses decorated with psychedelic colors and images, crazed rock concerts and the popular use of LSD and other psychoactive drugs. You might also think of dimly lit opium dens that were common in major cities throughout the 19th century, which seemed to hold forth the promise of exotic, mysterious, and perhaps dangerous experiences. Or, you might think of bohemian artists, writers, and revolutionaries drinking absinthe in the cafes and nightclubs of Paris around the same period.

You’ll notice that all these associations are strongly connected to the illicit, the socially transgressive, and the culturally subversive. Not only has the common conception of altered states been bound to illegal drug use in the popular imagination, but also with mental illness and its associated stereotypes. However, advances in the fields of neuroscience, anthropology, and ethnobotany have revealed that this is very far from the whole truth about altered states.

Research in these fields has yielded some astonishing insights into the nature and role of this phenomenon in the human brain and body. Most surprising of all is that ASCs share an underlying pattern of distinct brain functioning, regardless of how they are induced. Research suggests that this distinct pattern of brain functioning may be psychologically and physiologically beneficial for a range of anxiety and stress disorders that are still difficult to treat, for example, post-traumatic stress disorder (PTSD), depression, and end-of-life anxiety.

Defining Altered States

So what exactly are altered states of consciousness? Michael Winkelman, a retired professor of anthropology at Arizona State University who has written extensively about the use of entheogens by various indigenous groups throughout history, has proposed that ASC can be best defined as an “integrative mode of consciousness.” Within his neurophenomenological framework described in the book “Altering Consciousness: A Multidisciplinary Perspective,” which he co-edited and contributed to, Winkelman identifies this integration as constituting the biological foundation for the experiences of altered states, helping to reveal the answer for the presence and ritualization of ASC across peoples and cultures throughout history.

Common Biological Features of Altered States

Winkelman used the research that neuroscientist and psychiatrist Dr. Arnold Mandell conducted on the relationship between ecstatic states and patterns of brain functioning as a starting point for identifying the biological basis for ASC. He then went on to define altered states as a biological response that results in a distinct pattern of brain functioning and activity, regardless of the method of induction.

This pattern of brain function is mainly characterized by the synchronization of two important areas of the brain: the frontal cortex and the limbic system. The frontal cortex is the seat of executive function, which includes the processing of sensory information and high-level cognitive operations, involving abstract thought, planning, and judgment. The limbic system is deeply involved in processing emotions, the formation of memories, and learning.

Winkelman has explained that during ASC there is a shift from the typical pattern of sympathetic nervous-system dominance (state of biological alertness) and desynchronized fast-wave activity in the frontal cortex to a pattern of activity featuring parasympathetic dominance (state of biological relaxation) and the synchronization of the frontal cortex with other brain systems by slow-wave discharges ascending from the limbic system and related areas. This synchronization leads to integration between the most ancient parts of the brain — the structures within the limbic system and surrounding areas — and one of the most evolutionarily recent, the frontal cortex.

Another important characteristic feature is the reduction of serotonin inhibition in a variety of brain areas. In the hippocampus, an area of the brain that is responsible for memory formation and emotion, this reduction of inhibition leads to the production of the slow-wave discharges in the limbic system and also reduces the synaptic gating (regulation) of emotional responses. This, Mandell noted, leads to emotional flooding and feelings of ecstasy.