Document Detail

Long-term changes of GABAergic function in the sensorimotor cortex of amputees. A combined magnetic stimulation and 11C-flumazenil PET study.
MedLine Citation:
PMID:  10985690     Owner:  NLM     Status:  MEDLINE    
Primary sensory and motor areas of the cerebral cortex contain organised maps of the body. These maps appear to reorganise after damage to the peripheral parts of the sensory or motor systems, so that the cortical representation of undamaged structures expands at the expense of the damaged parts. Several studies in animals have suggested that decreased activity of the inhibitory GABAergic neurones is responsible for driving these changes. However, whether similar mechanisms sustain the effects in the longer term in humans is unknown. The present study addressed this question by examining reorganisation of sensorimotor areas of cortex in six unilateral upper limb amputees several years after the initial injury. We measured two independent indices of GABAergic function. Volumes of distribution of GABA(A) receptors were determined from 11C-flumazenil binding measured with positron emission tomography (PET). The strength of inhibition in the motor cortex was measured with paired-pulse transcranial magnetic stimulation. In the six amputees taken as a whole and compared with 24 normal subjects, there was a highly significant increase in 11C-flumazenil binding in the upper limb region of primary sensorimotor cortex bilaterally and in medial frontal cortex of the hemisphere contralateral to the amputation. Surprisingly, however, there was no change in the time course or strength of intra-cortical inhibition in the motor cortex of the amputees compared with matched control subjects. The increased 11C-flumazenil binding may reflect up-regulation of GABA(A) receptors to compensate for a decrease in the GABA content or activity of inhibitory neurones. Up-regulation of GABA(A) receptors may also indicate that long-term changes require stabilisation of cortical organisation.
C Capaday; M P Richardson; J C Rothwell; D J Brooks
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Experimental brain research     Volume:  133     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2001-01-09     Completed Date:  2001-01-09     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  552-6     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Brain Mapping / methods*
Carbon Radioisotopes / metabolism
Evoked Potentials, Motor / physiology*
Flumazenil / metabolism*
GABA Modulators / metabolism*
Middle Aged
Motor Cortex / metabolism*
Psychomotor Performance / physiology
Receptors, GABA-A / metabolism
Reg. No./Substance:
0/Carbon Radioisotopes; 0/GABA Modulators; 0/Receptors, GABA-A; 40P7XK9392/Flumazenil

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Caudal brainstem Fos expression is restricted to periventricular catecholamine neuron-containing loc...
Next Document:  Binswanger's encephalopathy: serial sections and morphometry of the cerebral arteries.