For the first time in history neuroscientists have taken deep look into what happens in a brain under the effects of lysergic diethylamide, or LSD. Scientists injected volunteers with 75 micrograms of LSD and imaged their brain using three advanced techniques while they were peaking, and were able to ascertain the causes of hallucinations, the altered perception of reality and the so-called “ego death.”
A powerful psychedelic drug that has had an immeasurable influence on today’s society, from music to computer software, its effect on the brain has remained mostly a mystery until now. The only other research on the effects of LSD is more than 50 years old, and used outdated tools compared to todays advanced methods of brain imaging and activity monitoring.
Relatively recent research studied the effects of the substances psilocybin (the active component in magic mushrooms) and dimethyltryptamine (present in Ayahuasca vines and the Yopo tree) and found the initial indications of what the psychedelic state looks like. Using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) scientists discovered that these two substances have an “entropic” effect on the brain and cause regions that don’t normally communicate with each other to start signaling.
LSD shares a chemical backbone with psilocybin and dimethyltryptamine, but it’s a fundamentally different drug. This latest research has unlocked some of the causes of hallucinations, and its insights into the altered perception of reality while on this drug give some explanation to the so-called “ego death,” as well as the feeling of “oneness” with nature, society or the entire Universe.
After taking 75 micrograms of LSD (which according to Erowid is a “common” dose, likely the equivalent of two hits of median-potency blotter tabs) scientists imaged the brains of subjects using several techniques while their eyes were closed. On the one hand, scientists observed that the visual cortex (the brain region responsible for sight) displayed higher levels of connectivity with other regions of the brain, explaining how feelings like emotion or different thought processes can carry over to the visual state and alter the visual experience.
The leader of the research, Dr. Carhart-Harris from the Imperial College London, explains that “We observed brain changes under LSD that suggested our volunteers were ‘seeing with their eyes shut’ — albeit they were seeing things from their imagination rather than from the outside world. We saw that many more areas of the brain than normal were contributing to visual processing under LSD — even though the volunteers’ eyes were closed. Furthermore, the size of this effect correlated with volunteers’ ratings of complex, dreamlike visions. ”
People who have taken LSD often note incessant, moving or still, geometric patterns that coat surfaces and objects in the visual field. During the experiment, participants had their eyes closed, but brain imaging showed their visual cortex was displaying all the characteristics of an open-eyes state, such as increased blood flow to the region. Instability in the visual cortex added to increased activity creates “self-organized patterns of neural excitation,” which manifests itself as hallucinations with geometric patterns. The visual cortex behaves as if a visual stimulus exists, but if none exists, it creates its own.
The above explains several features of closed-eye hallucinations, but what about for those with open eyes? The study found that LSD reduced “alpha power” in the brain could explain the chaotic nature of acid visuals. Alpha waves are neural oscillations that characterize the state of “wakeful rest,” such as in daydreaming, and is thought to have an inhibitory effect on erratic and irrelevant thoughts. Decreased alpha power and increased connectivity with the visual cortex could explain the different hallucinations an acid-tripper might experience.
Interestingly, LSD’s visual effects “did not significantly correlate with its more fundamental effects on consciousness.” Alpha brain waves also play a part in the functioning of the default mode network. The default mode network (DMN) is a series of highly inter-connected regions of the brain that are activated in states of restful consciousness, and this latest research suggests it may play a role in the “sense of self” of an individual. While tripping, feelings of “ego death” correlated with a pattern of disintegration of the DMN, but to their surprise, feelings of ego death did not generally happen at the same time as visual hallucinations.
When observing the overall effect of LSD on the brain, scientists noted increased communication between all regions of the brain, even ones that don’t normally interact. Dr. Carhart-Harris explained that, “”our brains become more constrained and compartmentalized as we develop from infancy into adulthood, and we may become more focused and rigid in our thinking as we mature. In many ways, the brain in the LSD state resembles the state our brains were in when we were infants: free and unconstrained. This also makes sense when we consider the hyper-emotional and imaginative nature of an infant’s mind.”
This latest research on LSD not only has important implications for the substance as a potential treatment for neuropsychiatric disorders, but may also help unlock one of the greatest mysteries in the world: the source of human consciousness.