Definition of Arousal and Mechanistic Studies in Intact and Brain‐Damaged Mice

The existence of a primitive, elemental form of CNS arousal, “generalized arousal,” has been hypothesized; it has been given an operational definition, and a high throughput assay has been assayed for it in mice. Many of the ascending and descending neuroanatomical pathways are fairly well understood. To begin experiments that might have potential implications for therapeutic measures, mice were rendered anoxic and it was shown that the assay can demonstrate behavioral abnormalities not detected with a standard neurological screen. These behavioral deficiencies are reminiscent of “sundowning,” a form of dementia seen in hospitalized elderly patients. Electrical stimulation of neurons in medial thalamic cell groups can increase activity in the generalized arousal assay. Current studies include attempts to achieve temporal patterns of electrical stimulation that would take advantage of nonlinear properties of ascending arousal pathways.