The Brain Metabolism of Unpredictable Signals

NCT ID: NCT05756335

Last Updated: 2023-03-06

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

NA

Total Enrollment

30 participants

Study Classification

INTERVENTIONAL

Study Start Date

2023-03-01

Study Completion Date

2025-02-28

Brief Summary

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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.

Detailed Description

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The proposed research consists of one experiment, combining positron emission tomography (PET) and magnetic resonance imaging (MRI) techniques to simultaneously estimate the cerebral metabolic rates of glucose (CMRglc) and oxygen (CMRO2), and their ratio (oxygen:glucose index; OGI). These outcome measures will be collected in the context of a behavioral intervention presenting subjects with predictable and unpredictable stimuli, and attended and unattended stimuli. Functional PET uses a slow infusion of 2-\[18F\]-fluro-deoxyglucose (FDG) to estimate regional CMRglc, measuring relative changes in radiotracer uptake between blocks of task and rest. Dual-calibrated fMRI uses a sequence of hyperoxic (increased O2) and hypercapnic (increased CO2) challenges, along with a specialized sequence of MRI scans (estimating cerebral blood flow and blood-oxygen level-dependent signal) to estimate absolute CMRO2.

All subjects will be scanned, and each will complete the same behavioral intervention. First, the investigators will aim to assess the reliability of this hybrid imaging technique by having subjects complete two identical scan sessions. Second, the investigators will deliver a behavioral intervention to test the relationship between stimuli predictability, CMRglc, CMRO2, and OGI.

This experimental design is capable of producing effects observable in single subjects, and prior studies using fPET and dual-calibrated fMRI have produced effect sizes that our sample size is more than adequate to detect.

Conditions

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Healthy

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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Behavioral intervention

Subjects are presented with a simultaneous sequence of faces and spoken words. Face stimuli include a representative sample of realistic faces across a range of ages. Spoken word stimuli are simple nouns spoken by a single female speaker.

Group Type EXPERIMENTAL

(Un)predictable and (un)attended stimuli

Intervention Type BEHAVIORAL

Subjects will complete four task conditions in each scan session: (1) Visual Unpredictable, (2) Visual Predictable, (3) Auditory Unpredictable, and (4) Auditory Predictable. In visual and auditory conditions subjects attend to visual or auditory stimuli and ignore the other domain, pressing a button when they detect an infrequently occurring stimulus inversion in the target domain. In unpredictable and predictable conditions, the attended domain either presents random (unpredictable) stimuli, or the same face or word stimuli repeated (predictable).

Interventions

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(Un)predictable and (un)attended stimuli

Subjects will complete four task conditions in each scan session: (1) Visual Unpredictable, (2) Visual Predictable, (3) Auditory Unpredictable, and (4) Auditory Predictable. In visual and auditory conditions subjects attend to visual or auditory stimuli and ignore the other domain, pressing a button when they detect an infrequently occurring stimulus inversion in the target domain. In unpredictable and predictable conditions, the attended domain either presents random (unpredictable) stimuli, or the same face or word stimuli repeated (predictable).

Intervention Type BEHAVIORAL

Eligibility Criteria

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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 consent
* Contraindications 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 scanner
* Pregnancy, seeking or suspecting pregnancy, or breastfeeding
* History of major head trauma
* Intracranial lesion
* Cardiovascular disorders, including heart disorders or high blood pressure \[\>155/95\]
* Breathing problems such as severe asthma, emphysema, or pulmonary disease
* Bleeding disorder, or use of anticoagulants
* Bladder obstruction, urinary problems, or history of impaired elimination
* Known kidney or liver problems
* Past severe COVID-19 infection
* Intestinal blockage
* Raynaud syndrome
* Anemia
* Peripheral nerve injury
* Diabetes
* Glaucoma
* Current or recent use of medications (neurological or psychiatric) affecting brain function
* Current or past history of major medical, neurological, or psychiatric condition
* Current or past history of chronic pain (assessed at the discretion of PI)
* Current smoker
* Body mass index above 35
* Research-related radiation exposure exceeds current Radiology Department guidelines
* Lack of current health insurance coverage
* Employed under the direct supervision of the investigators conducting the research
* Unwilling or unable to cooperate with breathing maneuvers required during the gas challenge
* Respiratory or cardiac limitations to breathing at 20 L/min
Minimum Eligible Age

21 Years

Maximum Eligible Age

35 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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Massachusetts General Hospital

OTHER

Sponsor Role lead

Responsible Party

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Christin Y. Sander, PhD

Assistant Professor

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Christin Y Sander, PhD

Role: PRINCIPAL_INVESTIGATOR

Athinoula A. Martinos Center for Biomedical Imaging

Locations

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Athinoula A. Martinos Center for Biomedical Imaging

Charlestown, Massachusetts, United States

Site Status

Countries

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United States

Central Contacts

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Irena Bass

Role: CONTACT

6177269034

Christin Y Sander, PhD

Role: CONTACT

6177269034

Facility Contacts

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Irena Bass

Role: primary

617-726-9034

Other Identifiers

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2022P002851

Identifier Type: -

Identifier Source: org_study_id

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