The Brain Metabolism of Unpredictable Signals

Healthy Clinical Trial

Official title:

Quantifying the Brain Metabolism Underlying Task-Based BOLD Imaging

Clinical Trial Details — Status: Not yet recruiting

Administrative data

• NCT number: NCT05756335
• Other study ID #: 2022P002851
• Status: Not yet recruiting
• Phase: N/A
• Start date: March 1, 2023
• Est. completion date: February 28, 2025

Study information

• Verified date: February 2023
• Source: Massachusetts General Hospital
• Contact: Irena Bass
• Phone: 6177269034
• Email: ibass[@]mgh.harvard.edu
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

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.

Description:

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.

Recruitment information / eligibility

• Status: Not yet recruiting
• Enrollment: 30
• Est. completion date: February 28, 2025
• Est. primary completion date: February 28, 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 21 Years to 35 Years

Eligibility

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

Related Conditions & MeSH terms

• Healthy

Intervention

Behavioral:
• (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).

Locations

Country	Name	City	State
United States	Athinoula A. Martinos Center for Biomedical Imaging	Charlestown	Massachusetts

Sponsors (1)

Lead Sponsor	Collaborator
Massachusetts General Hospital

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Brain positron emission tomography (PET) imaging signals	Changes in glucose metabolism will be quantified from brain PET images	after PET image analysis and with study completion, an average of 1 year
Primary	Functional magnetic resonance imaging (fMRI) signals	Changes in oxygen metabolism will be quantified from dual-calibrated fMRI	after fMRI image analysis and with study completion, an average of 1 year
Primary	Oxygen-glucose index	Ratio of cerebral metabolic rates of glucose and oxygen from PET and fMRI signals	after PET/fMRI image analysis and with study completion, an average of 1 year