Dose-Dependent Effect of Intranasal Insulin in Humans Using Functional Magnetic Resonance Imaging (fMRI)

Inclusion Criteria: * Participants in good health based on medical history, physical exam, and routine laboratory testing * Female participants must have a negative urine pregnancy test or be surgically sterilized or postmenopausal. Criteria for menopause are surgical menopause (hysterectomy, oophorectomy) or age \> 45 years with the absence of menses for greater than 12 months. * Body mass index (BMI) between 18 kg/m2 and 35 kg/m2 * Willing and able to stay at the clinical research facility as required by the protocol * Willing and able to comply with the investigational nature of the study and able to communicate well with investigators * Ability to comprehend and willing to provide written informed consent in accordance with institutional and regulatory guidelines * Ability to lie flat for a minimum of 2-hours Exclusion Criteria: * Known allergy to insulin. * Preexisting diabetes. * Current or previous use of diabetes medication or insulin. * Any nasal disease or congestion that may interfere with intranasal drug absorption. * Baseline hypoglycemia (blood glucose ≤ 65 milligrams per deciliter (mg/dL)) or hyperglycemia (blood glucose \> 200 mg/dL) as evident from the screening labs. * Active serious disease, such as liver disease, kidney disease, uncontrolled hypertension, clinically significant hypokalemia, and significant or unstable medical illness * Treated with an investigational drug within 30 days. * Individuals with inadequate venous access. * Claustrophobic, uncontrollable shaking, or unable to lie still for a lengthy period. * Any metals or implanted devices within the body. * Any foreign metallic objects in the body. * Females that are pregnant, trying to become pregnant, or breastfeeding