# Psychedelic 5-HT2A agonist increases spontaneous and evoked 5-Hz oscillations in visual and retrosplenial cortex

## TL;DR

A psychedelic drug increases 5-Hz brain waves in mouse visual and retrosplenial cortex, suggesting a link to altered perception and hallucinations.

## Contribution

The study reveals serotonin's role in modulating 5-Hz oscillations and top-down perception during altered brain states.

## Key findings

- 5-Hz oscillations in visual and retrosplenial cortex occur spontaneously and are evoked by visual stimuli.
- A 5-HT2AR agonist increases the power and persistence of these oscillations.
- The findings suggest enhanced top-down control of perception during altered states.

## Abstract

Visual perception appears largely stable in time. However, psychophysical studies have revealed that low frequency (0.5 – 7 Hz) oscillatory dynamics can modulate perception and have been linked to various cognitive states and functions. Neither the contribution of waves around 5 Hz (theta or alpha-like) to cortical activity nor their impact during aberrant brain states have been resolved at high spatiotemporal scales. Here, using cortex-wide population voltage imaging in awake mice, we found that bouts of 5-Hz oscillations in the visual cortex are accompanied by similar oscillations in the retrosplenial cortex, occurring both spontaneously and evoked by visual stimulation. Injection of psychotropic 5-HT2AR agonist induced a significant increase in spontaneous 5-Hz oscillations, and also increased the power, occurrence probability and temporal persistence of visually evoked 5-Hz oscillations. This modulation of 5-Hz oscillations in both cortical areas indicates a strengthening of top-down control of perception, supporting an underlying mechanism of perceptual filling and visual hallucinations.

The study highlights potential mechanisms of serotonin modulating consciousness and perception, indicating enhanced top-down processing during altered states.