A team of scientists have visualised the human brain under the influence of LSD, lysergic acid diethylamide, for the first time ever in a recent ground-breaking study.
Imperial College London researchers, working in association with the Berkley Foundation, have used imaging techniques to gain insight into the elusive effects that LSD has on the human brain. Since the early 1940s, the behavioural effects of LSD have become very clear from its use as a recreational drug, with it particularly being associated with hallucinations and altered consciousness with feelings of dissolution from the world. However, due to its banning in the 1960s, previous research into the neural basis of LSD’s actions has been limited to electroencephalography (EEG) as that was the only neuroimaging technique available at the time. This study therefore represents a long awaited step forward in our understanding of LSD’s prominent psychological features.
The study used a group of 20 healthy volunteers who had previously used psychoactive substances, in which each participant attended two separate scanning days; one for a placebo and one for the LSD. The volunteers were intravenously injected with either the saline placebo or 75mg LSD in a saline solution before being scanned using two types of functional magnetic resonance imaging (fMRI); arterial spin labelling (ASL) and blood oxygen-level dependent (BOLD) measures. These were followed by magnetoencephalography (MEG). Following injection, all of the subjects experienced hallucinations and changes in conciousness that were measured using questionnaires and ratings. The researchers could then compare the activity seen through the imaging techniques under placebo and LSD test conditions and how this related to the behavioural effects seen following LSD administration.
The results indicated an increase in cerebral blood flow (CBF) in the visual cortex when under the influence of LSD, which had previously been theorised as the cause of visual hallucinations. Further analysis also showed that there was greater connectivity between the primary visual cortex (V1) and other cortical and subcortical regions involved in the pathways usually used in vision and attending to visual stimuli, even though the participants had their eyes closed whilst being scanned. These findings led to Robin Carhart-Harris, one of the key researchers on the study, to suggest that the participants were ‘seeing with their eyes shut’, suggesting that the increased activity and connectivity could be accountable for the visual hallucinations caused by LSD, supported by the finding that they correlated with greater intensity of hallucinations.
In addition, they found that there was reduced connectivity between other brain regions, notably the parahippocampus and retrosplenial cortex. Furthermore, they noted that this correlated with measures of dissolution and thus this neural effect could be underlying the changes in consciousness that LSD seems to elicit.
As claimed by David Nutt, the senior researcher of the study and former drugs advisor for the government, LSD’s action can now be viewed as ‘reversing the more restricted thinking we develop from infancy to adulthood’ and this seminal study could lead the way to revamping our use of LSD, potentially for the treatment of psychological disorders with regimented thinking patterns like depression and anxiety disorders. Having said this, without any reduction in the current restrictions on the use of LSD in research, necessary studies with first-time users will not be able to take place. Nevertheless, deepening our understanding of LSD’s mechanisms could aid us in enhancing our understanding of consciousness as well, given the drugs profound effects on consciousness.
The full study can be found here: http://www.pnas.org/content/113/17/4853.full.pdf
Image credit: Imperial College London