GABA Levels in the Brains of Blind People

This study has been completed.
Sponsor:
Information provided by:
National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov Identifier:
NCT00357409
First received: July 26, 2006
Last updated: March 7, 2008
Last verified: March 2008
  Purpose

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.


Condition
Vision
Blind

Study Type: Observational
Official Title: GABA Levels in the Occipital Cortex of Blind Human Subjects

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 39
Study Start Date: February 2002
Estimated Study Completion Date: March 2008
Detailed Description:

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

Subjects 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. 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.

  Eligibility

Ages Eligible for Study:   18 Years to 55 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria
  • INCLUSION CRITERIA:

All subjects must be between 18 and 55 years of age.

Healthy sighted volunteers. Legally blind subjects with blindness secondary to retinal lesions or eye removal acquired at ages earlier than 4 years old (EARLY) and after 13 years of age (LATE). The rationale for the distinction is based in our previous studies that indicate different magnitude of brain plasticity depending on the age of acquisition of blindness.

EXCLUSION CRITERIA:

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.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00357409

Locations
United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
  More Information

Publications:
ClinicalTrials.gov Identifier: NCT00357409     History of Changes
Other Study ID Numbers: 020124, 02-N-0124
Study First Received: July 26, 2006
Last Updated: March 7, 2008
Health Authority: United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):
GABA
Occipital
Vision
Plasticity
MRS
Blind

ClinicalTrials.gov processed this record on September 29, 2014