Increased regional cerebral blood flow but normal distribution of GABAa receptor in the visual cortex of subjects with early-onset blindness

Before the completion of visual development, visual deprivation impairs synaptic elimination in the visual cortex.The purpose of this study was to determine whether the distribution of central benzodiazepine receptor(BZR)is also altered in the visual cortex in subjects with early-onset blindness. Positron emission tomography was carried out with [150]water and [11C]flumazenil on six blind subjects and seven sighted controls at rest, We found that the CBF was significantly higher in the visual cortex for the early-onset blind subjects than for the sighted control subjects. However, there was no significant difference in the BZR distribution in the visual cortex for the subject with early-onset blindness than for the sighted control subjects. These results demonstrated that early visual deprivation does not affect the distribution of GABAa receptors in the visual cortex with the sensitivity of our measurements. Synaptic elimination may be independent of visual experience in the GABAergic system of the human visual cortex during visual development