Clinical Research Directory

Inclusion Criteria: * Fluent in English * Willingness and ability to comply with scheduled visits, magnetic resonance imaging (MRI) scanning, laboratory tests, and other study procedures. * Subjects with well-controlled vascular risk factors, such as treated hypertension, treated hyperlipidemia or well controlled Type II diabetes will be included. * Stable medications for at least 30 days. * Mini Mental State Exam adjusted for age and education of 25 to 30, inclusive or a Telephone Interview for Cognitive Status score of at least 32 * Perform within 1.5 S.D. of age and education matched norms on the Logical Memory Paragraph Delayed Recall * Geriatric Depression Scale \< 11 * Aged 60-85, inclusive * Right-handed * Reduced vision is allowed if it can be corrected with MRI-goggles Exclusion Criteria: * Prior known diagnosis of mild cognitive impairment (MCI) or dementia * Use of investigational drugs or devices within 60 days prior to screening * Subjects with contraindications to MRI cannot participate (i.e., implanted metal including pacemakers, cerebral spinal fluid shunts, aneurysm clips, artificial heart valves, ear implants or metal/foreign objects in the eyes and those with a history of claustrophobia) * Pregnant. * Major psychiatric disorders such as schizophrenia, schizoaffective disorder, major affective disorder in mid-life, or treatment with electroconvulsive therapy (ECT) (Mild depression that is well treated with stable dose of selective serotonergic reuptake inhibitor (SSRI) antidepressants will be allowed). * Have a history of major head trauma defined as a loss of consciousness and/or trauma requiring hospitalization * Substance abuse within the past 2 years * Active hematological, renal, pulmonary, endocrine or hepatic disorders. * Evidence of cortical infarcts or strategically placed lacunar infarct (e.g. dorsal medial nucleus of thalamus). MRI evidence of mild white matter signal abnormalities will be allowed. * Active cancer, metabolic encephalopathy, infection * Active cardiovascular disease, stroke, congestive or severe heart failure * Huntington's disease, hydrocephalus or seizure disorder * Cataracts, glaucoma, detached retina's, eye surgery involving the muscles; droopy eyelids, penetrating eye wounds and use of anticholinergic eye drop use * Weight equal to or greater than 300 lbs (weight limit of the MRI table). * Recurrent vaso-vagal syncopal episodes * Unilateral or bilateral vagotomy * Severe valvular disorder (i.e. prosthetic valve or hemodynamically relevant valvular diseases) * Sick sinus syndrome * Hypotension due to autonomic dysfunction