by Andy Bui

A UC Berkeley study is breaking new ground with a pioneering study that could change our understanding of visual perception, brain function, and the effects of psychedelics on the mind.

Led by Professor Michael Silver, an expert in visual perception, attention, and neuroscience, this study marks the first time in the history of the University of California, Berkeley that a psychedelic substance—specifically psilocybin—is being administered to human subjects.

A Passion for Vision Science and Neuroscience

Professor Michael Silver, a faculty member at UC Berkeley since 2005, has always been fascinated by how the brain constructs visual experiences. As the faculty director of the UC Berkeley Center for the Science of Psychedelics (BCSP) since its opening in 2020, his research delves into the psychological, physiological, and neurochemical mechanisms that shape human perception. Silver spoke about his childhood curiosity surrounding visual illusions, a curiosity that ultimately led him to pursue a career in neuroscience.

“Our experience of the world does not always match the state of the world,” said Silver.

While his research began with animal studies, Silver transitioned to human research over time, focusing on the cognitive factors that influence visual perception and associated brain activity. With the opening of the BCSP, funded by a generous donor, Silver and his team began to develop the infrastructure on campus necessary to launch a groundbreaking study on the effects of psychedelics on vision and brain function.

Psychedelics and the Brain: A Window into Consciousness

The novel study, which began in June 2024, seeks to explore how psychedelics like psilocybin—a naturally occurring psychedelic compound produced by mushrooms—impact human perception. Specifically, this study will analyze how psilocybin affects the brain’s use of past experiences, or “priors,” when processing sensory input. In the context of this study, priors are cognitive biases or expectations, based on regularly occurring patterns in the visual environment, that shape how we perceive the world. By combining sensory inputs with these priors, the brain constructs our visual experience. The study aims to examine how psychedelics might influence this process by potentially relaxing the influence of priors, leading to altered visual perceptions.

“Psychedelics have very distinctive effects on visual perception and hold great potential for experimental neuroscience to understand the mind, brain, and consciousness,” Silver said.

One of the theoretical frameworks guiding the research is the Relaxed Beliefs Under Psychedelics (REBUS) theory, which suggests that psychedelics reduce the influence of rigid, entrenched beliefs, offering a chance to “reset” the brain. When combined with trained therapists, this approach has shown promise in therapeutic settings for treating mental health disorders such as PTSD, anxiety, and depression. Silver hopes to apply this theory to the visual system—utilizing current available knowledge of this system’s relationship to neuroscience studies.

Mapping Brain Activity in Real Time

The design of the study is as innovative as its concept. Participants will receive a dose of psilocybin while undergoing functional magnetic resonance imaging (fMRI) scans. A non-invasive technique that measures brain activity by tracking blood flow and blood oxygen levels in real-time, fMRI scans show a dynamic story of brain function that allows researchers to observe how different regions of the brain respond to various stimuli or are engaged by different experimental tasks or cognitive states.

For this study, participants will be shown visual stimuli that can be perceptually interpreted in two different ways. This setup will allow researchers to track when and how participants switch between these two interpretations: one that is more influenced by priors and beliefs, and another that is more based on direct sensory signals. The researchers will gain insights into how psychedelics affect the brain’s interpretation of visual information.

The team will also gather subjective data through both structured and open-ended surveys, which will be correlated with the brain activity data, allowing participants to narrate their personal experiences and the researchers to relate participants’ subjective experiences with their brain activity.

Overcoming Challenges: Regulatory and Scientific Hurdles

While the promise of the research is significant, the road to conducting this study has been paved with challenges. Psychedelics are still classified as a Schedule I controlled substance by the DEA, which adds regulatory complexity. Because psilocybin is a Schedule I compound, the FDA categorizes the study as a clinical trial, requiring rigorous oversight, record-keeping, and compliance with both federal and state regulations.

Silver’s team had to develop new protocols, training, and infrastructure to handle psilocybin, work with human subjects, and navigate the regulatory maze. 

Another challenge lies in the inherent difficulty of isolating the effects of psilocybin. Expectation effects—how much participants anticipate the drug’s impact—can skew results. To address this, the study employs a blinded design in which neither the participants nor the researchers know what dose of psilocybin is being used for each session until after completion of the study. The BCSP team is also quantifying each participant’s expectations prior to any drug administration.

The Future: Insights into Mental Health, Vision, and Consciousness

Looking ahead, Silver is hopeful that this study will provide critical insights into the relationships among the mind, brain, and consciousness. Beyond adding to basic knowledge, he believes the study could have profound implications for mental health treatment. By understanding how psychedelics affect brain activity and subjective experience, researchers may be able to develop more effective treatments for conditions like depression, anxiety, and PTSD. Furthermore, the research could help counter misinformation about psychedelics by providing evidence-based, scientific insights into their potential benefits.

“The aim is to obtain insights about the relationships among the mind, brain, and consciousness,” Silver said. “Because the work has been suppressed for so long, there’s a lot of fundamental research that still needs to be done.”

Silver’s ultimate goal is to foster a deeper understanding of how psychedelics work in the brain, not only as potential therapeutic agents but also as tools for advancing our understanding of human perception and consciousness. Through this research, he hopes to contribute to the broader discourse on psychedelics and their role in medicine, all while emphasizing a grounding in scientific inquiry.

A New Era of Research at UC Berkeley

Silver’s study is a historic step forward in the fields of neuroscience, vision science, and psychedelics research. By exploring the effects of psilocybin on visual perception and the brain’s processing of sensory information, Silver and his team are opening the door to new understandings of consciousness, mental health, and the way our brains construct reality. As the study progresses, it could lay the groundwork for future therapeutic breakthroughs and help pave the way for a more nuanced and scientifically-informed conversation about psychedelics and their potential.