# Abstract

**Background:**

Psychedelics induce profound changes in perception and thinking; however, little is known about the neural mechanisms and prediction of these effects.

**Aims:**

Investigating [ayahuasca🌀](https://www.reddit.com/r/NeuronsToNirvana/search/?q=Ayahuasca)\-induced experiences, mind-wandering, and electroencephalogram (EEG) oscillations, beyond the prediction of subjective experiences by baseline EEG.

**Methods:**

In a randomised, double-blind, placebo-controlled, parallel-arm design, 50 healthy volunteers received 1 mL/kg of ayahuasca or placebo. We measured subjective psychedelic experiences (Hallucinogen Rating Scale (HRS), Mystical Experience Questionnaire (MEQ)) and mind-wandering (Amsterdam Resting-State Questionnaire (ARSQ)). EEG signals were assessed before administration (+0h), and 2 hours (+2h) and 4 hours (+4h) post-administration. Relationships between subjective and EEG effects were examined.

**Results:**

Ayahuasca, compared to placebo, induced subjective experiences, including changed perception, cognition, emotion (HRS), mystical experiences (MEQ), and visual, discontinuous, and content-laden thinking (ARSQ). Ayahuasca, compared to placebo, changed EEG oscillations, including decreased global alpha as well as increased frontomedial delta and right posterior theta and beta. Under ayahuasca, lower theta correlated with higher mystical experiences (MEQ) and higher alpha correlated with lower Thoughts about Nothing (ARSQ). Baseline global EEG oscillations predicted ayahuasca-induced experiences, with lower theta linked to higher interoception (HRS Heart Beat, HRS Rush, ARSQ Somatic Awareness) and lower beta linked to higher positive emotionality (HRS Happy).

**Conclusion:**

Ayahuasca induced consciousness alterations, visual, bodily, emotional, and mystical experiences, chaotic and meaningful mind-wandering, and decreased especially alpha. While acute theta seems inversely related to mystical experiences, baseline theta and beta seem to inversely predict interoception and emotionality.

# 🧠 Ayahuasca EEG Study — Full Summary + Regional Theta, Alpha, Beta Changes and Caudate Implications

# Study Design

* 50 healthy volunteers
* Randomised, double-blind, placebo-controlled
* 1 mL/kg ayahuasca vs placebo
* EEG at 0h, +2h, +4h
* Measures: HRS, MEQ, ARSQ

# 🌈 Key Subjective Findings

Ayahuasca significantly increased:

* Perceptual, cognitive, emotional effects (HRS)
* Mystical-type experiences (MEQ)
* Discontinuous, content-rich mind-wandering (ARSQ)

# ⚡ EEG Changes (Region-Specific, Not Global)

# 1. Global Alpha ↓

* Classic psychedelic marker
* More entropy, less top-down constraint
* Predicts more chaotic free-associative mentation

# 2. Frontomedial Delta ↑

Linked to:

* Interoception
* Deep emotional processing
* ACC/mPFC salience network activation

# 3. Right-Posterior Theta ↑

This is the key:

* Theta *increased* specifically in right posterior cortex
* Supports vivid imagery, dream-like visuals, spatial distortions
* Fits the “ayahuasca visionary space” phenomenology

# 4. Right-Posterior Beta ↑

* Increased precision of visual predictions
* Heightened emotional salience of internal imagery

# 🔗 Correlations Between EEG and Subjective Experience

# Lower acute theta → stronger mystical experiences (MEQ)

* Despite posterior theta ↑
* Overall/global theta ↓ predicted deeper mystical states
* Shows theta is *not uniform*: region matters

# Higher alpha → fewer “Thoughts about Nothing” (ARSQ)

* Alpha retains structure → less blank mind-wandering

# 🔮 Baseline EEG Predictors (Before the Dose)

# Lower baseline theta → more interoception

* Heartbeat sensations, somatic rushes, bodily awareness
* Suggests individuals with low resting theta are more sensitive to bottom-up bodily signals

# Lower baseline beta → more positive emotionality

* Beta regulates emotional control; lower baseline = greater emotional openness

# 🧬 Was the Caudate Nucleus Affected?

The study did not directly record deep structures via EEG, but the pattern **strongly implies cortico–striatal modulation** involving the caudate.

Why?

* Frontomedial delta ↑ = ACC/mPFC → striatal loops
* Alpha ↓ = reduced top-down gating → increased subcortical influence
* Beta ↑ in right posterior cortex = classical cortico–striatalthalamo–cortical loop activity
* Ayahuasca components (DMT/harmine) act on 5-HT2A and sigma-1 receptors abundant in the caudate

# Caudate-related cognitive/emotional features match the findings:

* Heightened meaning
* Symbolic significance
* Dream-like narrative flow
* Emotional salience
* Internal visual simulation

So although **not measured**, the pattern is consistent with **caudate involvement** in ayahuasca’s mystical, emotional, and imaginal effects.

# 🌀 One-Sentence Interpretation

Ayahuasca increases posterior theta (imagery), increases frontomedial delta (interoception), decreases global alpha (entropy), and shifts cortico–striatal dynamics, producing a combined state of vivid visionary immersion and deep mystical dissolution.

🧠 Ayahuasca🌀EEG Study — Full Summary + Regional Theta, Alpha, Beta Changes and Caudate Implications | Abstract; 🚫 |  Predicting and exploring ayahuasca effects: Perception, mind-wandering, and EEG oscillations | Journal of Psychopharmacology [Dec 2025]