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Leanne M Williams

Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California.

4 papers in the library · 62 citations · publishing 2023-2026

Papers

UNRAVELing the synergistic effects of psilocybin and environment on brain-wide immediate early gene expression in mice.

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology November 1, 2023 Daniel Ryskamp Rijsketic, Austen B Casey, Daniel A N Barbosa et al. 49 citations

Psilocybin increased neural activity (c-Fos expression) in the neocortex, caudoputamen, central amygdala, and parasubthalamic nucleus while decreasing it in the hypothalamus, cortical amygdala, striatum, and pallidum of mice, largely regardless of whether the mice were in their home cage or an enriched environment. Network analyses showed that psilocybin disrupted co-activity between highly correlated brain regions, reduced modularity, and attenuated communication between modules. Context and psilocybin each had widespread effects on brain activity and network architecture, but interactions between the two were surprisingly sparse.

Negative Affect Circuit Subtypes and Neural, Behavioral, and Affective Responses to MDMA: A Randomized Clinical Trial.

JAMA network open April 1, 2025 Xue Zhang, Laura M Hack, Claire Bertrand et al. 10 citations

In a double-blind, placebo-controlled trial, 16 adults with subthreshold PTSD symptoms and early life trauma but no current psychiatric disorders were given 120 mg of MDMA or placebo. Participants were split into two groups based on baseline brain activity in the amygdala in response to nonconscious threat cues: those with high amygdala reactivity (NTNA+) and those with low reactivity (NTNA-). MDMA, compared with placebo, reduced activity in the amygdala and subgenual anterior cingulate cortex (sgACC), increased connectivity between the sgACC and amygdala, and increased liking of threatening facial expressions, but only in the NTNA+ subgroup. These findings suggest that baseline neural circuit profiles can identify who may benefit most from MDMA therapy and point to possible biomarkers for personalized treatment.

Oral ketamine effects on dynamics of functional network connectivity in patients treated for chronic suicidality.

European archives of psychiatry and clinical neuroscience May 21, 2024 Zack Y Shan, Adem T Can, Abdalla Z Mohamed et al. 3 citations

Ketamine treatment for chronic suicidality alters how brain networks synchronize and transition over time. In a 6-week open-label trial with 29 patients, those who received ketamine showed significantly more transitions among whole-brain connectivity states after treatment. At a 10-week follow-up, patients spent more time in and more frequently visited a highly synchronized brain state, and these changes correlated with reduced suicidal ideation scores. Patients who persistently responded to ketamine had a higher baseline fraction of a cognitive control network state with strong connections, suggesting that pre-treatment brain connectivity patterns may help predict who will benefit from ketamine therapy. These findings point to a biological mechanism for ketamine's suicide-prevention effects.

Psychedelics disrupt hierarchical cortical propagations in the default mode network of humans and mice.

Proceedings of the National Academy of Sciences of the United States of America June 16, 2026 Adam R Pines, Xue Zhang, John Kochalka et al.

Psychedelic drugs consistently reduce the strength and bottom-up direction of signal flow within the brain's default mode network, according to analyses of four independent datasets spanning humans and mice and three different psychedelic compounds (MDMA, psilocybin, and LSD). This attenuation of cortical propagations is not explained by data quality or previously known effects of psychedelics and is uniquely tied to self-reported outcomes. The findings clarify how psychedelics alter macroscale hierarchical processing in the brain.