Psilocybin Disrupts Brain Waves in the Anterior Cingulate Cortex New research reveals how psilocybin alters neural activity in the anterior cingulate cortex, reducing low-frequency brain waves and disrupting neuronal phase-locking in awake mice. Recent neurophysiological research indicates that psilocybin significantly alters neural activity in the anterior cingulate cortex, a brain region critical for emotional processing and internal awareness. The study, conducted by researchers at the University of Bristol, provides a detailed look at how the active ingredient in magic mushrooms affects single brain cells and networks in awake mice. By utilizing electrodes to record activity from individual neurons and local field potentials, the team analyzed the effects of a 2 mg/kg dose of psilocybin. This specific dosage allows scientists to estimate human-equivalent effects while observing how the substance impacts higher cognitive functions associated with the prefrontal cortex.Neural Activity and Brain Wave ShiftsThe analysis revealed that psilocybin induces a pronounced shift in brain wave frequencies during the peak experience phase. Specifically, slower oscillations, including delta, theta, and alpha waves, were significantly reduced. In contrast, the power of faster gamma waves increased substantially.These oscillations facilitate communication between different brain regions, with slow waves typically managing information flow between distant areas and gamma waves handling local interactions. The observed shift suggests that the anterior cingulate cortex transmits and receives less information from faraway brain regions, indicating a reduction in top-down processing.Disruption of Neuronal Phase-LockingAt the cellular level, approximately 40 percent of neurons increased their activity under the influence of psilocybin. However, this heightened excitability came at the cost of regularity. The phenomenon known as phase-locking, where neurons fire in coordination with brain oscillations, degraded significantly.Neurons typically communicate via action potentials or burst firing, where multiple spikes occur in quick succession. While burst firing generally supports neuroplasticity, psilocybin caused a complex change where neurons that increased their burst firing also reduced their degree of phase-locking.The REBUS Model of Psychedelic ActionThese findings support the Relaxed Beliefs Under Psychedelics (REBUS) model proposed by Robin Carhart-Harris and Karl Friston. The model posits that psychedelics disrupt the influence of top-down modulation on sensory information, allowing the brain to rely less on prior beliefs and be more receptive to incoming sensory input.The chaotic manner in which psilocybin increases activity in the anterior cingulate cortex appears symptomatic of this reduced top-down influence. By disrupting the regularity of brain activity, the substance may enable a state where the brain prioritizes immediate sensory data over established expectations.Future Research Directions in NeurophysiologyWhile these results provide a critical data point, they represent only one step toward understanding the ground truth of psilocybin effects. As an associate professor of Neurophysiology, the lead researcher emphasizes the need for further study to get closer to the ground truth of what psilocybin is doing to brain activity.The study, published in Scientific Reports, highlights the complex interplay between neural excitability and regularity. These insights into how psilocybin affects the anterior cingulate cortex may eventually inform therapeutic applications for psychiatric conditions involving emotional processing.