The purpose of this trial is to study the brain response using functional MRI (fMRI) before and after varying doses of insulin given through the nose. The magnetic resonance imaging uses a very strong magnet to produce images of participant's brain. It becomes a functional MRI when the study team looks at the activity within the brain (blood flow / change in metabolism).

If cardiac arrest is not treated immediately, it causes sudden death. Intranasal insulin may be a way to prevent the brain injury that occurs after a cardiac arrest or other brain injury. Even when immediate treatment gets the heart beating again, many victims remain comatose and die later from brain injury. Nasal insulin reduces brain injury in animal experiments and has been used to try to improve brain degeneration in patients with Alzheimer's disease in doses up to 160 units.

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