Clinical trial NCT02482571: Metabolic Changes in the Activated Human Visual Cortex During Mild Hypoxia
Official title: Metabolic Changes in the Activated Human Visual Cortex During Mild Hypoxia
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Brain Hypoxia
Keywords: Functional MRS
Glutamate
Lead sponsor: University of Minnesota
Sponsor class: OTHER
First posted: 2015-06-26
Enrollment: 25
Sex: MALE
Minimum age (years): 18
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: The primary objective of this research is to measure changes in neurochemical concentrations during stimulation of the primary visual cortex, in both conditions of normoxia (normal oxygen availability) and induced mild hypoxia (reduced oxygen availability).

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 spectroscopy (fMRS) to estimate metabolic changes during a visual stimulus, 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.

Eligibility criteria: 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.
* Females.
* 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.

Primary outcomes:
measure: Change in Glutamate Concentration During a Visual Stimulus Measured by fMRS at Normoxia
timeFrame: Baseline and Visual Stimulation at 4 minutes
measure: Change in Glutamate Concentration During a Visual Stimulus Measured by Functional MRS at Hypoxia
timeFrame: Baseline and Visual Stimulation at 4 minutes
Secondary outcomes:
measure: Brain Activity Measured by Blood Oxygenation Level Dependent (BOLD) Signal at Normoxia
timeFrame: Baseline and Visual Stimulation at 30 seconds
measure: Brain Activity Measured by Blood Oxygenation Level Dependent (BOLD) Signal at Hypoxia
timeFrame: Baseline and Visual Stimulation at 30 seconds
Other outcomes:
Locations:
city: Minneapolis
country: United States
facility: Center for Magnetic Resoance Research, University of Minnesota
state: Minnesota
Study officials:
affiliation: University of Minnesota
name: Silvia Mangia, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Ho YC, Vidyasagar R, Shen Y, Balanos GM, Golay X, Kauppinen RA. The BOLD response and vascular reactivity during visual stimulation in the presence of hypoxic hypoxia. Neuroimage. 2008 Jun;41(2):179-88. doi: 10.1016/j.neuroimage.2008.02.048. Epub 2008 Mar 6.
citation: Tuunanen PI, Murray IJ, Parry NR, Kauppinen RA. Heterogeneous oxygen extraction in the visual cortex during activation in mild hypoxic hypoxia revealed by quantitative functional magnetic resonance imaging. J Cereb Blood Flow Metab. 2006 Feb;26(2):263-73. doi: 10.1038/sj.jcbfm.9600186.