Noninvasive measurement of regional cerebral blood flow, neuropsychological tests, and CT scans are being compared in normal volunteers between 18-100 years of age, in subjects without brain disease but with risk factors for cerebral arteriosclerosis (hypertension, diabetes, hyperlipidemia) and in patients with cerebrovascular disorders including: transient ischemic attacks, cerebral infarction, subarachnoid and intracranial hemorrphage, multi-infarct and related dementias, migraine and vascular headache. The effects of activation procedures including different types of brain work, changes in PECO2 and PEO2 are being compared in normals and those with risk factors and patient populations. The mechanisms of cerebral infarction and diaschisis are being examined in the baboon by CT scanning plus application of new methods for measuring cerebral hemispheric brain stem and cerebellar blood flow already applied to man. Cerebral blood flow is being measured serially with the EEG changes after unilateral cerebral infarction, before and after corpus callosum section. Detailed correlation of higher cortical functions are being made in patients with stroke by automated self-assessment devices as well as by conventional psychological test batteries. Innovative methods of 3 dimensional computer analysis of CT scans in stroke are being developed. The effects of various types of stroke on the stages of the sleep-wake cycle are being assessed and the basic disorder of lipid metabolism underlying cerebral antherogenesis is being explored.