PROJECT SUMMARY
Psychedelics are chemicals best known for their ability to induce profound changes in the human
conscious experience. After a several-decade hiatus, research on psychedelics is undergoing a renaissance,
driven by their potential to treat psychiatric disorders with rapid onset and enduring effect. Recent research
reveals that psychedelics can rapidly promote the structural and functional plasticity of synapses, leading to the
conjecture that neural plasticity underlies their long-term therapeutic values. However, the neurobiological
mechanisms remain largely elusive. Our overarching goal is to understand the cellular and circuit mechanisms
underlying psychedelics’ long-lasting therapeutic effects. In this proposal, we focus on the classical serotonergic
psychedelic psilocybin and investigate how it rescues the deleterious effects of stress, a major risk factor for
many neuropsychiatric disorders. Our central hypothesis is that psilocybin affects the brain at multiple levels,
from synaptic plasticity to the functional network; although psilocybin only transiently enhances synapse
formation, it permanently alters the synaptic circuit in an experience-dependent manner; the incorporation of new
synapses into the neural circuit is essential for psilocybin’s long-lasting rescue of stress-induced functional and
behavioral deficits. Specifically, in Aim 1, we will determine the acute and enduring effects of psilocybin on the
stressed brain, particularly on the structural reorganization of synaptic circuits, on cortical functional networks,
and on the representation of behavioral variables by cortical neuronal ensembles. Aim 2 determines how the
environmental and behavioral contexts in which psilocybin is administered impact its rescuing effects on the
stressed brain. Aim 3 determines the contribution of psilocybin-induced neuroplasticity, particularly the
stabilization of newly formed dendritic spines, to its rescuing effects on the stressed brain. Overall, these studies
will provide an integrated, mechanistic understanding of psilocybin’s rescuing effects across the organizational
hierarchy of the brain, from molecules and synapses to circuits and functional networks, and lay the foundation
for its clinical application in treating stress-related psychiatric disorders.