What part of the brain does lsd affect
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LSD's Impact on Brain Function: Key Affected Regions
Amygdala and Emotional Processing
LSD significantly affects the amygdala, a brain region crucial for emotional processing. Research using functional magnetic resonance imaging (fMRI) has shown that LSD reduces the reactivity of the left amygdala and the right medial prefrontal cortex when subjects are exposed to fearful stimuli. This reduction in amygdala activity correlates with the subjective effects of the drug, suggesting that LSD modulates emotional responses by altering amygdala function 1.
Visual Cortex and Hallucinations
The visual cortex is another critical area influenced by LSD. Studies employing various neuroimaging techniques, such as arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) measures, have demonstrated increased cerebral blood flow and decreased alpha power in the visual cortex under the influence of LSD. These changes are strongly associated with the visual hallucinations characteristic of the psychedelic experience. Additionally, LSD expands the functional connectivity profile of the primary visual cortex (V1), further enhancing its hallucinatory effects 2.
Cortico-Striato-Thalamo-Cortical (CSTC) Pathways
LSD also impacts the cortico-striato-thalamo-cortical (CSTC) pathways, which are essential for sensory and sensorimotor information processing. The drug alters directed connectivity within these pathways, particularly increasing connectivity from the thalamus to the posterior cingulate cortex and decreasing connectivity from the ventral striatum to the thalamus. These changes are mediated by the serotonin 2A receptor, highlighting its role in the psychedelic state induced by LSD 3.
Thalamus and Global Connectivity
The thalamus plays a pivotal role in the brain's global connectivity under the influence of LSD. The drug increases thalamocortical connectivity and enhances the functional connectivity of the primary visual cortex with other brain areas. These effects are linked to the subjective experiences of hallucinations and ego dissolution, where the boundaries between self and environment become blurred 410.
Prefrontal Cortex and Monoamine Pathways
LSD affects the prefrontal cortex, particularly in its interactions with monoamine pathways. Research on rats has shown that LSD impedes transmission in serotonin (5-HT) systems within the prefrontal cortex, which may contribute to its profound psychological effects. The drug's impact on catecholamine systems, however, appears to be more region-specific and less understood 9.
Conclusion
LSD exerts its profound effects on consciousness and perception by modulating activity and connectivity in several key brain regions, including the amygdala, visual cortex, CSTC pathways, thalamus, and prefrontal cortex. These changes are primarily mediated through the serotonin 2A receptor, underscoring its critical role in the psychedelic experience. Understanding these neural mechanisms provides valuable insights into the potential therapeutic applications of LSD in treating various psychiatric conditions.
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Acute effects of LSD on amygdala activity during processing of fearful stimuli in healthy subjects
LSD acute administration reduces amygdala and medial prefrontal cortex activity during fearful stimuli processing in healthy subjects.
RCT
Very Rigorous Journal
Highly CitedNeural correlates of the LSD experience revealed by multimodal neuroimaging
LSD causes significant changes in brain activity, influencing visual hallucinations and altering consciousness, with decreased connectivity between the parahippocampus and retrosplenial cortex playing a key role.
Observational StudyHighly CitedEffective connectivity changes in LSD-induced altered states of consciousness in humans
LSD alters directed connectivity within cortico-striato-thalamo-cortical pathways, potentially causing disintegration of information processing and contributing to the psychedelic state.
RCTHighly CitedChanges in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor
LSD's neuropharmacology is primarily influenced by the 5-HT2A receptor, which plays a critical role in its neurobiology and guide the development of psychedelic-based therapeutics.
RCT
Rigorous JournalHighly CitedLSD alters dynamic integration and segregation in the human brain
LSD alters brain dynamics, increasing small-worldness and complexity of segregated states, leading to ego-dissolution and bridging pharmacodynamics, subjective experience, and brain dynamics.
Non-RCTVery Rigorous JournalHighly CitedIncreased sensitivity to strong perturbations in a whole-brain model of LSD
LSD intake leads to increased brain complexity and response diversity, potentially benefiting psychiatric disorders.
Very Rigorous JournalModern Clinical Research on LSD
LSD can induce bliss, audiovisual synesthesia, altered perceptions, and mystical experiences, with potential therapeutic potential in psychiatry.
Literature ReviewRigorous JournalHighly CitedTranscriptomics-informed large-scale cortical model captures topography of pharmacological neuroimaging effects of LSD
LSD alters cortical functional topography through serotonin-2A-mediated modulation of pyramidal cell gain, predicting altered states of consciousness and linking molecular-level manipulations to brain changes.
Rigorous JournalLSD: effect on monoamine metabolites in rat prefrontal cortex.
LSD administration impairs transmission in 5-HT-containing neuronal systems, but its effects on catecholamine systems remain unclear, with regional brain differences potentially influencing its effects.
Non-RCT
Animal StudyIncreased Global Functional Connectivity Correlates with LSD-Induced Ego Dissolution
LSD selectively expands global connectivity in the brain, compromising its modular organization and perceptual boundaries between self and environment, leading to ego dissolution.
Non-RCTHighly Cited