Water Oxygenation and Brain Activity

Inclusion Criteria: * Men or women of any ethnic background; * living in New York tri-state area; * fluent in English; * normal or corrected to normal vision and hearing; * willing to complete all study procedures; and * capable of giving written informed consent. Exclusion Criteria: * A history of gross brain abnormalities such as stroke, severe ventriculomegaly or severe periventricular white matter abnormalities; * a history of serious psychiatric or neurological disorders, including psychosis or major depression, alcohol or drug abuse, brain injury, seizure disorder, brain tumor, etc.; * taking psychoactive medications, including antipsychotics, anxiolytics and antidepressants, or cognitive enhancers such as cholinesterase inhibitors; * presence of contraindications for MEG or MRI recording, including any of the following: cardiac pacemaker, intracranial clips, metal implants, or external clips within 10 mm of the head, metal in eyes, claustrophobia, obesity and/or any other reason leading to difficulty staying in the MEG or MRI for up to one hour.