Consequences of acute injury or challenge to the brain. It is typically intense and short lived. The integrative, well-moderated nature of the brain is affected so that functions are turned on inappropriately. Causal examples might include fever, intoxication, brain injury, and aftereffects of some anesthesias. In effect, people act "crazy," reflecting the active, turned-on state of the brain. There can be hallucinations, unnecessary behavior, and agitation.