GABA Levels in the Brains of Blind People
Condition: Vision; Blind
Study type: Observational

Summary: 
      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.
    

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.
    

Keywords: GABA; Occipital; Vision; Plasticity; MRS; Blind