Psilocybin and 2C-B at Encoding Distort Episodic Familiarity

Area of Science:

• Neuroscience
• Psychopharmacology
• Cognitive Psychology

Background:

• Research into psychedelics, such as psilocybin and 2C-B (serotonin receptor 2A agonists), is expanding.
• A key area of investigation is whether these compounds share unique effects on memory formation.
• Specifically, psychedelics may impair hippocampal-dependent recollection while enhancing cortical-dependent familiarity.

Purpose of the Study:

• To investigate the acute effects of psilocybin and 2C-B on the encoding of emotional episodic memories.
• To determine if these psychedelics differentially impact recollection and familiarity.
• To examine the influence of psychedelics on memory confidence and metamemory.

Main Methods:

• A double-blind, placebo-controlled, within-participants study was conducted with 20 participants.
• Participants viewed negative, neutral, and positive pictures during acute drug effects (psilocybin or 2C-B).
• Memory for the pictures was assessed the following day using separate tests.

Main Results:

• Trends indicated that psilocybin and 2C-B impaired recollection estimates during encoding.
• Both psychedelics impaired familiarity estimates, likely due to misattribution, as evidenced by increased familiarity-based false alarms, especially for emotional stimuli.
• Metamemory estimates for negative and neutral memories were impaired, while those for positive memories showed enhancement, though with less reliability.

Conclusions:

• Both psilocybin and 2C-B significantly distorted episodic familiarity, despite their distinct properties.
• This suggests a common neurocognitive mechanism underlying memory alterations across different psychedelic substances.
• These shared mechanisms may contribute to other observed phenomena associated with psychedelic use.