Up to one third of people who experience migraines get a preceding aura, in which they may sense a strange light or unpleasant smell. Some have noted that they smell burnt toast preceding a migraine.

Migraine is believed to be caused by the release of a chemical called serotonin or 5HT into the bloodstream from its storage sites in the body, resulting in changes in the neurotransmitters and blood vessels in the brain. Exactly what causes this to happen is still a subject for research and debate.

Although the exact cause of migraine remains unknown, the most widespread theory is that it’s a disorder of the serotonergic control system. Recently, PET scans have demonstrated the aura to coincide with spreading cortical depression after an episode of greatly increased blood flow (up to 300% higher than baseline). There also appear to be migraine variants that originate in the brainstem and involve dysfunction in calcium and potassium ion transport between cell membranes.

I guess I clipped this because I can relate..I get awful migraines from time to time, and never realized that there were other people who also "smell burnt toast" when one is coming on, in my case, it's more like burnt GARLIC toast!

wow some of those jagged white line drawings look exactly like i'm getting a migraine!