GlossaryTrigeminal pathway

Trigeminal pathway

The trigeminal nerve system (cranial nerve V) responsible for transmitting pain signals from the face, scalp, and meninges to the brain. Becomes sensitised and hyperactivated during cluster headache and migraine attacks. Psilocybin may modulate trigeminal pain pathways via 5-HT2B and 5-HT2C receptor activity — a mechanism distinct from its 5-HT2A-mediated antidepressant effects. This distinction may explain why psilocybin's headache benefits do not correlate with psychedelic intensity.

Full Explanation

The trigeminal pathway is the trigeminal nerve system (cranial nerve V) responsible for transmitting pain signals from the face, scalp, and meninges to the brain. It becomes sensitised and hyperactivated during cluster headache and migraine attacks. Psilocybin may modulate trigeminal pain pathways via 5-HT2B and 5-HT2C receptor activity — a mechanism distinct from its 5-HT2A-mediated antidepressant effects. This distinction may explain why psilocybin's headache benefits do not correlate with psychedelic intensity.

See: Cluster Headaches (/conditions/cluster-headaches).

Why It Matters

The trigeminal pathway explains why psilocybin can help cluster headache through a different mechanism than depression — and why sub-psychedelic doses can still be effective.

Related Terms

5-HT2B receptor

5-HT2A receptor

Back to Glossary

Explore More Terms

5-HT2B receptor

A serotonin receptor subtype expressed in cardiovascular tissue, the gastrointestinal system, and the trigeminal system. Distinct from the 5-HT2A receptor that mediates psilocybin's psychedelic and antidepressant effects. 5-HT2B and 5-HT2C agonism may mediate psilocybin's preventive effects on cluster headaches and migraines at sub-psychedelic doses — explaining why therapeutic headache benefits occur independently of the intensity of the psychedelic experience. Chronic 5-HT2B agonism at high doses raises theoretical cardiovascular concerns, though this is not a documented issue at therapeutic psilocybin doses.

5-HT2A receptor

The primary serotonin receptor in the brain that psilocin binds to, producing psychedelic effects.

Y-BOCS

Yale-Brown Obsessive Compulsive Scale — the primary validated outcome measure used in OCD clinical research. Assesses symptom severity across obsessions and compulsions on a 0–40 scale (0 = no symptoms, 40 = extreme). A reduction of 35% or more from baseline is generally considered clinically significant. Used in all psilocybin OCD trials as the key efficacy endpoint. In the 2006 University of Arizona pilot study, participants showed 23–100% Y-BOCS reductions across dosing sessions. (Moreno et al., Journal of Clinical Psychiatry, 2006)

Ego dissolution

The temporary softening or loss of the sense of a separate self during a psychedelic experience. Measurable on the Ego-Dissolution Inventory (EDI) and correlated with therapeutic outcomes in depression, addiction, and end-of-life anxiety trials. Driven by 5-HT2A agonism and reduced default mode network activity. Related to — but not identical with — the pop term "ego death": ego dissolution is a graded, commonly reported feature of a full-dose session; ego death is the extreme end of that spectrum.

Afterglow

The period of heightened mood, openness, and mental flexibility that commonly follows a full-dose psilocybin session — typically lasting 24 hours to several weeks. During the afterglow, neuroplasticity is elevated, default mode network activity is altered, and emotional and cognitive patterns are unusually open to change. Considered the critical integration window: therapeutic insights translate into lasting behavior change most effectively during this period. (Majić et al., 2015)

Spores

Reproductive cells produced by mushrooms, used to start new cultures and legal to possess in most US states.