Cortical Desynchronization (Fast Timescale)
This demo illustrates the fast-timescale effect of serotonergic psychedelics: increasing gain weakens synchronization in a coupled oscillator field, spreading activity across more independent modes (MEG-like Deff increase). The companion paper shows this is only half the story — at slow hemodynamic timescales, the observed BOLD covariance can become more low-dimensional, even after global signal removal.
Cortical Oscillators
5-HT2A Gain Modulation (Fast Timescale)
Synchronized: Low gain creates strong coupling. Oscillators lock to shared phase (high R). The cortex is constrained.
Desynchronized: High gain weakens coupling. Oscillators decouple (low R). More independent modes become active.
External Drive: When synchronization is weak, external inputs can drive the system more easily.
MEG analyses show serotonergic psychedelics increase effective dimensionality (Deff +15%, p=0.003). This demo visualizes the fast-timescale desynchronization via the Kuramoto order parameter R. At slow hemodynamic timescales, the effect reverses.
What This Demo Shows
Kuramoto Oscillators (Fast Layer)
Each cell represents a local cortical population with its own intrinsic frequency. Neighboring populations are coupled — they tend to synchronize, like pendulums on a shared beam. This creates the large-scale waves visible at low gain.
Gain Modulation (Psychedelic Intuition)
5-HT2A agonism is often modeled as increased dendritic gain. In a coupled oscillator system, higher gain can amplify local perturbations, weakening phase-locking and promoting desynchronization.
What We Measure Here
The live metric shown is the Kuramoto order parameter R (global synchrony). Lower R means less global phase-locking. This demo is a conceptual illustration of the fast electrophysiological regime.
What This Demo Is Not
This is not a hemodynamic forward model and does not simulate BOLD. In the companion paper, slow fMRI covariance shifts in the opposite direction (PC1 ↑, Deff ↓) despite fast desynchronization. The lesson: dimensionality depends on timescale and measurement channel.
What the Paper Found
In MEG analyses, serotonergic psychedelics show increased effective dimensionality (Deff +15%, p = 0.003), consistent with reduced synchronization at fast timescales. Ketamine (NMDA antagonist) does not show the same directional change.
The key result: the slow hemodynamic channel behaves differently. In a precision-mapping psilocybin fMRI dataset, covariance becomes more low-dimensional (Deff −10%, PC1 ↑), and this persists after global signal regression (p = 0.036).
"Psychedelic entropy" is observation-operator dependent, not a single brain-wide scalar.