Biological psychiatry. Cognitive neuroscience and neuroimaging
July 1, 2024
Sepehr Mortaheb, Larry D Fort, Natasha L Mason et al.
15 citations
Psilocybin produces profound alterations in both brain connectivity and subjective experience. In a randomized study, healthy volunteers received psilocybin or placebo and underwent ultrahigh field 7T fMRI scanning during the peak drug effect. Psilocybin caused widespread increases in averaged brain functional connectivity and a recurrent hyperconnected brain pattern with low blood oxygen level-dependent signal amplitude, suggesting heightened cortical arousal. This hyperconnected pattern was linked to feelings of oceanic boundlessness and visionary restructuralization. The brain's tendency to enter this hyperconnected-hyperarousal state may underlie the variant mental associations characteristic of the psychedelic experience.
bioRxiv (Cold Spring Harbor Laboratory)
September 18, 2023
Sepehr Mortaheb, Larry D. Fort, Natasha L. Mason et al.
7 citations
preprint
Psilocybin increases functional connectivity across the brain and induces a recurrent hyperconnected pattern with low BOLD signal amplitude, suggesting heightened cortical arousal. These brain dynamics are linked to feelings of oceanic boundlessness and visionary restructuralization, as measured by the 5-Dimensional Altered States of Consciousness Rating Scale. The brain's tendency to enter this hyperconnected-hyperarousal pattern under psilocybin may enable variant mental associations. For the first time, these findings connect brain dynamics with phenomenological alterations, offering new insights into the neurophenomenology and neurophysiology of the psychedelic state.
Frontiers in Neuroscience
February 13, 2024
Benedetta Cecconi, Javier Montupil, Sepehr Mortaheb et al.
6 citations
Disconnected consciousness, where subjective experience persists but is cut off from the external world, often occurs during sleep or sedation but is difficult to study because unresponsive people may still be conscious and amnesia can erase memories of events. This research uses a serial awakening paradigm during mild propofol sedation: participants hear sounds and are interviewed while still sedated to determine whether they are connected or disconnected from the environment, bypassing the need for behavioral responses and amnesia. Functional MRI data reveal neural activity patterns during these states, testing whether sensory disconnection arises at the thalamus or from disrupted information flow to higher brain regions. Slow-wave activity's role is also explored via high-frequency BOLD oscillations. Findings could improve anesthesia monitoring and assessment of patients with reduced consciousness.
Biological Psychiatry
October 21, 2025
Katharina S Lege, Pablo Mallaroni, Sepehr Mortaheb et al.
1 citation
Acute cannabis intoxication alters brain network dynamics, reducing the occurrence of a hyperconnected brain state in both occasional and chronic users. Chronic users show persisting neuroadaptations, including decreased brain network segregation, independent of intoxication. Attentional performance is most impaired in occasional users, suggesting tolerance develops in chronic users. Both acute and persistent effects on brain dynamics correlate with spatial CB1 receptor density. The findings indicate that cannabis-induced cognitive impairment depends on individual neuroadaptations and receptor density, relevant for therapeutic, legal, and societal contexts.