Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany; Center for Intervention and Research on adaptive and maladaptive brain Circuits underlying mental health (C-I-R-C), Halle-Jena-Magdeburg, Germany; German Center for Mental Health (DZPG), partner site Halle-Jena-Magdeburg, Germany.
2 papers in the library · 3 citations · publishing 2024
In healthy men, a thinner posterior cingulate cortex (PCC) is linked to a stronger feeling of disembodiment after a low dose of ketamine, a drug that can rapidly relieve depression. The study measured cortical thickness in two brain regions—the PCC and the pregenual anterior cingulate cortex (pgACC)—and found that only PCC thickness correlated with the altered sense of self (disembodiment). No such link appeared for the pgACC. These results suggest the PCC plays a key role in ketamine's effects on self-experience, a feature shared with other fast-acting antidepressants that also produce psychedelic-like effects.
Ketamine causes temporary dissociative experiences alongside its rapid therapeutic effects. This study examined whether pleasant and unpleasant dissociations can be predicted by functional connectivity of the posteromedial cortex (PMC) in 35 male participants during ultrahigh-field MRI. Pleasant dissociation (oceanic boundlessness) was predicted by PMC connections with control network regions at baseline and during infusion, and additionally with default mode network regions during infusion. Unpleasant dissociation (anxious ego dissolution) could not be predicted by PMC connectivity. The findings suggest distinct brain mechanisms for pleasant versus unpleasant dissociations, and that PMC connectivity changes may be a shared neural feature of dissociation from both ketamine and psychedelics.