1. A method for determining whether brain activity of a human subject in response to a stimulus of interest is characteristic of a state of interest, comprising the steps of: (a) providing a stimulus of interest; (b) measuring brain activity of said subject in response to said stimulus during a period of interest; (c) comparing the brain activity in at least one brain region when measured during said period of interest with a predetermined control level of activity; and (d) determining whether the brain activity in said at least one brain region when measured during said period of interest is characteristic of said state of interest based upon said comparison.