Serotonergic Hallucinogen-Induced Visual Perceptual Alterations.

Area of Science:

• Neuroscience
• Psychopharmacology
• Visual Perception

Background:

• Serotonergic hallucinogens like LSD, psilocybin, and DMT induce profound visual alterations.
• These alterations include intensified colors, illusions, altered self-reference, and complex hallucinations.
• The diversity of these phenomena suggests multiple underlying neuropsychopharmacological mechanisms.

Purpose of the Study:

• To explore the neurobiological mechanisms behind hallucinogen-induced visual phenomena.
• To link cellular-level receptor activation to systemic changes in brain activity and visual processing.
• To explain the diverse range of visual experiences reported under hallucinogens.

Main Methods:

• Review of cellular mechanisms, focusing on 5-HT2A receptor activation and cortical excitation.
• Analysis of anatomical and dynamical brain features linking excitation to hallucination content.
• Examination of systemic mechanisms, including alpha oscillation decrease and visual evoked potentials (N170, P1).

Main Results:

• 5-HT2A receptor activation increases cortical excitation, a key cellular mechanism.
• Decreased alpha oscillations amplify internal brain signals, overriding external stimuli.
• Reduced N170 and increased medial P1 potentials indicate a dysbalance in visual processing, affecting global integration and early gain.

Conclusions:

• Hallucinogen-induced visual experiences result from a complex interplay of mechanisms.
• 5-HT2A receptor activation, altered cortical excitation, and changes in brain oscillations and evoked potentials contribute to visual phenomena.
• A dysbalance between global integration and early visual gain likely underlies hallucinations, illusions, and intensifications.