Low doses of LSD (13 and 26 micrograms) produced broad reductions in brain wave power across multiple frequency bands during rest and dampened specific event-related potentials (P300 and N170) during a visual task in healthy adults. The drug also increased positive mood, energy, and anxiety, as well as heart rate and blood pressure, but did not cause the full perceptual or sensory changes typical of higher psychedelic doses. These neurophysiological effects resemble those seen with higher doses, suggesting that very low LSD doses might produce subtle behavioral or therapeutic effects without inducing a full psychedelic experience.
Electrical stimulation of the posteromedial cortex (PMC) can induce a temporary sense of self-dissociation—a distorted awareness of one's body in space and feeling like an outside observer to one's own thoughts. A patient with seizures originating in the right dorsal posterior cingulate cortex (Brodmann area 31) reported this reproducible experience at seizure onset. Stimulating the seizure zone or a homotopical region in the left PMC at 50 Hz induced a subjectively similar state. The findings suggest a causal link between the PMC and the integration of self-referential information, offering clues about the pathophysiology of self-dissociation in neuropsychiatric conditions.