Decreased benzodiazepine receptor density in the cerebellum of early blindhuman subjects

As a first approach to study the effect of early visual deprivation in the GABA-ergic inhibitory system, the distribution of benzodiazepine receptors (BZR) was accurately estimated using [C-11]flumazenil ([C-11]FMZ). Measurem ents were carried out in five subjects who became blind early in life and i n five sighted control subjects. The interactions between [C-11]FMZ and BZR were described using a non-linear compartmental analysis which permitted t o estimate the BZR synaptic density independently of other model parameters . The distribution of BZR in the visual areas and other cortical regions of blind subjects was qualitatively and quantitatively similar to that of con trols. However, the BZR density in the cerebellum was significantly lower i n blind than in control subjects (P<0.01). Our findings suggest that modifi cations of the cerebellar neural circuitry may be concomitant to the alread y observed compensatory reorganization in cerebral areas of blind subjects. (C) 2001 Elsevier Science B.V. All rights reserved.