Increased thalamic resting‐state connectivity as a core driver of LSD‐induced hallucinations
Acta Psychiatrica Scandinavica – September 21, 2017
Source: OpenAlex
Summary
Lysergic acid diethylamide (LSD) profoundly alters brain connectivity, offering new insights into Consciousness. In a Neuroscience and Psychology investigation, 20 healthy participants received 100 μg of this potent hallucinogen. Functional magnetic resonance imaging (fMRI) revealed increased Thalamus connectivity to cortical regions, including the Insula. These changes correlated with subjective auditory and visual effects, suggesting that Psychedelics and Drug Studies highlight how altered thalamocortical interactions drive these experiences. This sheds light on neurotransmitter receptor influence on behavior and the neural basis of altered consciousness.
Abstract
Objective It has been proposed that the thalamocortical system is an important site of action of hallucinogenic drugs and an essential component of the neural correlates of consciousness. Hallucinogenic drugs such as LSD can be used to induce profoundly altered states of consciousness, and it is thus of interest to test the effects of these drugs on this system. Method 100 μg LSD was administrated orally to 20 healthy participants prior to fMRI assessment. Whole brain thalamic functional connectivity was measured using ROI ‐to‐ ROI and ROI ‐to‐voxel approaches. Correlation analyses were used to explore relationships between thalamic connectivity to regions involved in auditory and visual hallucinations and subjective ratings on auditory and visual drug effects. Results LSD caused significant alterations in all dimensions of the 5D‐ ASC scale and significantly increased thalamic functional connectivity to various cortical regions. Furthermore, LSD ‐induced functional connectivity measures between the thalamus and the right fusiform gyrus and insula correlated significantly with subjective auditory and visual drug effects. Conclusion Hallucinogenic drug effects might be provoked by facilitations of cortical excitability via thalamocortical interactions. Our findings have implications for the understanding of the mechanism of action of hallucinogenic drugs and provide further insight into the role of the 5‐ HT 2A ‐receptor in altered states of consciousness.