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Metabolic Changes in the Activated Human Visual Cortex During Mild Hypoxia

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ClinicalTrials.gov Identifier: NCT02482571
Recruitment Status : Active, not recruiting
First Posted : June 26, 2015
Last Update Posted : February 1, 2018
Information provided by (Responsible Party):
University of Minnesota - Clinical and Translational Science Institute

Brief Summary:
The primary objective of this research is to measure neurochemicals in the activated human brain during both normoxia (normal oxygen availability) and induced mild hypoxia (reduced oxygen availability).

Condition or disease Intervention/treatment
Brain Hypoxia Device: Mild Hypoxia

Detailed Description:
The goal is to determine the effect of mild hypoxia on human brain energy metabolism of healthy young adult subjects. For this purpose, the Investigator will utilize non-invasive imaging modalities based on functional magnetic resonance imaging (fMRI) and spectroscopy (fMRS), while subjects are exposed to well-controlled gas mixtures that resembles conditions of either normoxia or mild hypoxia. Identifying the impact of mild hypoxia on functional brain energy metabolism in the healthy human brain is a crucial step for generating hypotheses in multiple patient populations that experience mild hypoxia as consequence of their pathological condition, such as in sleep apnea and traumatic brain injury. The Investigator hypothesize that the energetic demands of neuronal activation as revealed by fMRS will not be affected by mild hypoxia, despite an altered hemodynamic response observed with fMRI.

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 25 participants
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Metabolic Changes in the Activated Human Visual Cortex During Mild Hypoxia
Actual Study Start Date : March 2016
Primary Completion Date : December 2016
Estimated Study Completion Date : December 2018

Arm Intervention/treatment
Experimental: Mild Hypoxia
Subjects are exposed to an intervention that controls the composition of breathed air by using a gas blender (RespirAct). Subjects undergo MRI and MRS while breathing air with both normal oxygen concentration (normoxia) and reduced oxygen concentration (mild hypoxia).
Device: Mild Hypoxia
During normoxia, the computer-controlled gas blender provides a gas mixture that generates pressures of expired O2 and CO2 similar to the resting values measured for each subject (32-35mmHg and 100-110 mmHg, respectively). During mild hypoxia, we will target the same expired CO2 of normoxia and a 60 mmHg reduction of expired O2 from the resting value (to a minimum limit of 50 mmHg), which is expected to reduce arterial oxygen saturation to 82-85%. In mild hypoxia, the fraction of inspired oxygen is reduced from ~21% (room air) to ~12% (equivalent to an altitude of 4000 meters). During both conditions of normoxia and mild hypoxia, the brain activity of subjects is monitored with functional magnetic MRI (fMRI) and spectroscopy (fMRS) while they are presented with visual stimuli.

Primary Outcome Measures :
  1. Concentration of brain metabolites measured by functional MRS [ Time Frame: Baseline ]

Secondary Outcome Measures :
  1. Brain activity measured by functional MRI [ Time Frame: Baseline ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Those volunteers who are evaluated as normal and not met exclusion criteria will be potential candidates for this study.

Exclusion Criteria:

  • Subjects with any type of bio-implant activated by mechanical, electronic, or magnetic means (e.g. cochlear implants, pacemakers, neurostimulators, biostimulators, electronic infusion pumps, etc.).
  • Subjects with any type of ferromagnetic bio-implant that could potentially be displaced or damaged, such as aneurysm clips, metallic skull plates, etc.
  • Pregnant females (if questionable doubt, self-test with over the counter pregnancy kit).
  • Subjects that exhibit noticeable anxiety and/or claustrophobia.
  • Subjects who cannot adhere to the experimental protocol for any reason.
  • Subjects who have cardiac or known circulatory impairment, and/or the inability to perspire (poor thermoregulatory function).
  • Subjects who have known conditions which can lead to emergency medical care.
  • Been diagnosed by a physician as having a psychiatric disorder, substance abuse, neurological, cardiovascular.
  • Been diagnosed by a physician as having respiratory diseases.
  • Had a brain tumor or stroke.
  • Started taking chemotherapy or immunomodulatory agents, or had any radiation treatment that could affect the brain.
  • Had two or more seizures, or been given a diagnosis of epilepsy.
  • Gotten a non-removable piercing or permanent eyeliner.
  • Had a head injury that caused you to lose consciousness for more than 30 minutes or have amnesia for more than 24 hours.
  • Anyone with a history of sleep apnea or head trauma that may have caused Traumatic Brain Injury (TBI).
  • Gotten some type of metal in your body, either from a medical procedure or an injury.
  • Male subjects with long beard which wouldn't allow a complete seal between the mask and the face.
  • Anyone who is not able to see long distance without glasses or contacts.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02482571

United States, Minnesota
Center for Magnetic Resoance Research, University of Minnesota
Minneapolis, Minnesota, United States, 55455
Sponsors and Collaborators
University of Minnesota - Clinical and Translational Science Institute
Principal Investigator: Silvia Mangia, PhD University of Minnesota - Clinical and Translational Science Institute

Additional Information:
Responsible Party: University of Minnesota - Clinical and Translational Science Institute
ClinicalTrials.gov Identifier: NCT02482571     History of Changes
Other Study ID Numbers: 201503M65382
First Posted: June 26, 2015    Key Record Dates
Last Update Posted: February 1, 2018
Last Verified: January 2018
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Keywords provided by University of Minnesota - Clinical and Translational Science Institute:
Functional MRS
Functional MRI

Additional relevant MeSH terms:
Hypoxia, Brain
Signs and Symptoms, Respiratory
Signs and Symptoms
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases