The Brain Metabolism of Unpredictable Signals

The investigators will be studying brain glucose and oxygen metabolism using hybrid PET/fMRI imaging to better understand how decoupling between brain glucose and oxygen metabolism relates to the processing of unpredictable sensory signals.

Inclusion Criteria:Adults aged 21-35.No contraindications to MRI or PET scanning.Right-handed.Fluent to speak, read, and understand English.Exclusion Criteria:Adults unable to consentContraindications to fMRI scanning and PET scanning (including the presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia)Inability to lie motionless in the scannerPregnancy, seeking or suspecting pregnancy, or breastfeedingHistory of major head traumaIntracranial lesionCardiovascular disorders, including heart disorders or high blood pressure [>155/95]Breathing problems such as severe asthma, emphysema, or pulmonary diseaseBleeding disorder, or use of anticoagulantsBladder obstruction, urinary problems, or history of impaired eliminationKnown kidney or liver problemsPast severe COVID-19 infectionIntestinal blockageRaynaud syndromeAnemiaPeripheral nerve injuryDiabetesGlaucomaCurrent or recent use of medications (neurological or psychiatric) affecting brain functionCurrent or past history of major medical, neurological, or psychiatric conditionCurrent or past history of chronic pain (assessed at the discretion of PI)Current smokerBody mass index above 35Research-related radiation exposure exceeds current Radiology Department guidelinesLack of current health insurance coverageEmployed under the direct supervision of the investigators conducting the researchUnwilling or unable to cooperate with breathing maneuvers required during the gas challengeRespiratory or cardiac limitations to breathing at 20 L/min