GABA Levels in the Brains of Blind People

Completed

Conditions studied: Vision, Blind

In brief

In blind individuals, the occipital cortex becomes capable of processing tactile and auditory information, a phenomenon described as crossmodal plasticity. GABA is the major inhibitory neurotransmitter in the brain and a possible candidate to mediate this form of human plasticity. We intend to use magnetic resonance spectroscopy (MRS) to measure GABA and hypothesize that GABA levels in the occipital cortex of blind humans will be lower than in sighted controls. Such decrease could possibly mediate compensatory changes in the occipital cortex of the blind. Objective Early blind subjects exhibit better tactile acuity than late blinds or sighted individuals. The purpose of the study is the determine GABA levels in the human occipital cortex after long-term light deprivation (blindness). Study Population Our experiments will make use of early blind, late blind, and sighted control subjects. Design Subject will be identified and will receive clinical and neurological examinations at the NIH. MRS studies will be performed at NIH MRI Center with 3Tesla Magnet. Each subject head will be positioned in an adjustable holder (designed for minimal motion and maximal comfort) such that a flat coil lay just below the occipital cortex. The sequence has been described before \[33\]. The individuals who perform the data analysis will be blind to the purpose of the experiments. Outcome measures The concentration of GABA from the 14 ml voxel over the visual cortex will be measured. Edited proton spectrum of GABA will be compared with the edited sub spectrum of creatine for a concentration reference.

Key facts

Study ID

NCT00357409

Run by

National Institute of Neurological Disorders and Stroke (NINDS)

People needed

39

Starts

2002-02-11

Expected to finish

2008-03-03

Last updated by the study team

2017-07-02

Who can join

Age: 18 and older, up to 55. Sex: any. Healthy volunteers: accepted.

You may not qualify if…

• Exclusion criteria will be those of MRI procedures:
• Pregnant women tested after urine pregnancy test.
• Subjects with metal in the cranium except mouth.
• Subjects with metal fragments from occupational exposure or surgical clips in or near the brain.
• Subjects with blood vessel, cochlear or eye implants.
• Subjects with increased intracranial pressure as evaluated by clinical means.
• Subjects with cardiac or neural pacemakers.
• Subjects with intracardiac lines and implanted medication pumps.

Where it is running

• National Institutes of Health Clinical Center, 9000 Rockville Pike — Bethesda, Maryland, United States

Full record on ClinicalTrials.gov

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