Enhanced Repertoire of Brain Dynamical States During the Psychedelic Experience

ENZO TAGLIAZUCCHI; ROBIN CARHART-HARRIS; DAVID NUTT; DANTE R. CHIALVO

Human Brain Mapping

Wiley

Año: 2014

1097-0193

The study of rapid changes in brain dynamics and functional connectivity (FC) is of increasinginterest in neuroimaging. Brain states departing from normal waking consciousness are expected to beaccompanied by alterations in the aforementioned dynamics. In particular, the psychedelic experienceproduced by psilocybin (a substance found in ?magic mushrooms?) is characterized by unconstrainedcognition and profound alterations in the perception of time, space and selfhood. Considering the spon-taneous and subjective manifestation of these effects, we hypothesize that neural correlates of the psyche-delic experience can be found in the dynamics and variability of spontaneous brain activity fluctuationsand connectivity, measurable with functional Magnetic Resonance Imaging (fMRI). Fifteen healthy sub-jects were scanned before, during and after intravenous infusion of psilocybin and an inert placebo.Blood-Oxygen Level Dependent (BOLD) temporal variability was assessed computing the variance andtotal spectral power, resulting in increased signal variability bilaterally in the hippocampi and anteriorcingulate cortex. Changes in BOLD signal spectral behavior (including spectral scaling exponents)affected exclusively higher brain systems such as the default mode, executive control, and dorsal atten-tion networks. A novel framework enabled us to track different connectivity states explored by the brainduring rest. This approach revealed a wider repertoire of connectivity states post-psilocybin than duringcontrol conditions. Together, the present results provide a comprehensive account of the effects of psilo-cybin on dynamical behavior in the human brain at a macroscopic level and may have implications forour understanding of the unconstrained, hyper-associative quality of consciousness in the psychedelicstate.