Credit: Jason Schneider

It's 2:00 p.m. on a Tuesday, and I'm feeling stupid and slightly grumpy. I have lingering jet lag because I took a trip to London last week and flew in last night from California. Now I'm sitting in the Brain Stimulation Unit of the National Institute of Neurological Disorders and Stroke in Bethesda, MD, with two electrodes affixed to my forehead. In a moment, a researcher in the lab of neurologist Eric Wassermann will activate a gizmo the size of a small clock radio, which will send an electric current through my frontal lobe, the part of the brain most associated with higher reasoning and emotion. For the next 40 minutes, the flow of electrons will create an electric field that lets neurons having to do with cognition and emotion fire more easily.

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