This placebo-controlled study (n=19), which also used computational modeling, argues that LSD (75μg) increased reward learning rates heightened plasticity, which in turn could be the mechanism through which psychedelics help reshape maladaptive (‘stuck’) patterns.
“Background The non-selective serotonin 2A (5-HT2A) receptor agonist lysergic acid diethylamide (LSD) holds promise as a treatment for some psychiatric disorders. Psychedelic drugs such as LSD have been suggested to have therapeutic actions through their effects on learning. The behavioural effects of LSD in humans, however, remain incompletely understood. Here we examined how LSD affects probabilistic reversal learning (PRL) in healthy humans.
Methods Healthy volunteers received intravenous LSD (75 μg in 10 mL saline) or placebo (10 mL saline) in a within-subjects design and completed a PRL task. Participants had to learn through trial and error which of three stimuli was rewarded most of the time, and these contingencies switched in a reversal phase. Computational models of reinforcement learning (RL) were fitted to the behavioural data to assess how LSD affected the updating (‘learning rates’) and deployment of value representations (‘reinforcement sensitivity’) during choice, as well as ‘stimulus stickiness’ (choice repetition irrespective of reinforcement history).
Results Raw data measures assessing sensitivity to immediate feedback (‘win-stay’ and ‘lose-shift’ probabilities) were unaffected, whereas LSD increased the impact of the strength of initial learning on perseveration. Computational modelling revealed that the most pronounced effect of LSD was the enhancement of the reward learning rate. The punishment learning rate was also elevated. Stimulus stickiness was decreased by LSD, reflecting heightened exploration. Reinforcement sensitivity differed by phase.
Conclusions Increased RL rates suggest LSD induced a state of heightened plasticity. These results indicate a potential mechanism through which revision of maladaptive associations could occur in the clinical application of LSD.”
Authors: Jonathan W. Kanen, Qiang Luo, Mojtaba R. Kandroodi, Rudolf N. Cardinal, Trevor W. Robbins, David J. Nutt, Robin L. Carhart-Harris & Hanneke E. M. den Ouden
Find this paper
Effect of lysergic acid diethylamide (LSD) on reinforcement learning in humans
Open Access | Google Scholar | Backup | 🕊
December 9, 2020
Neuroscience Creativity Depression Treatment-Resistant Depression
Placebo-Controlled Single-Blind Within-Subject Re-analysis
The psychedelics given at which dose and how many timesLSD 75 μg | 1x
Linked Research Papers
Notable research papers that build on or are influenced by this paperNeural correlates of the LSD experience revealed by multimodal neuroimaging
Using three different neuroimaging techniques (ASL, BOLD, MEG), this single-blind, placebo-controlled study highlighted the neurological underpinnings of the LSD/psychedelic (75μg) experience.