Visual Hallucinations in Serotonergic Psychedelics and Lewy Body Diseases

Area of Science:

• Neurology
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Visual hallucinations (VH) are a core symptom in Lewy body diseases (LBDs) and with serotonergic psychedelic (SP) use.
• Despite differing causes, overlapping phenomenology and neural mechanisms suggest shared pathways between LBD- and SP-induced VH.

Purpose of the Study:

• To compare the phenomenology, cortical function, and serotonergic modulation of VH in LBDs and SPs.
• To explore potential shared neural mechanisms underlying VH in these distinct conditions.

Main Methods:

• A narrative review synthesizing findings from neurology, cognitive neuroscience, and systems neuroscience.
• Analysis of studies involving human subjects and animal models examining cortical activity, neuromodulatory mechanisms, and VH phenomenology.

Main Results:

• Both LBDs and SPs present with diverse visual aberrations, with some LBD features mirroring SP-induced phenomena.
• Neuroimaging reveals common patterns of hyperactive associative cortex and hypoactive sensory cortex.
• Shared neuromodulatory findings include serotonin 2A receptor involvement and altered cortical excitation/inhibition balance.

Conclusions:

• Understanding shared cortical and neuromodulatory similarities in VH can illuminate the relationship between sensory processing and hallucination generation.
• Future research using real-time neuroimaging during hallucinatory episodes is crucial for identifying shared mechanisms and developing targeted LBD interventions.