Energy metabolism is closely coupled to functional activity in most tissues, including those of the CNS. Deoxyglucose labeled with carbon 14 can be used to measure rates of glucose use in all anatomic and functional components of the CNS. Using radioautography of serial sections of the brain, pictorial representation of the relative rates of glucose use are obtained. These radioautographs are like a stain for functional activity in nervous tissue and can be used to identify regions with altered functional activity in varying physiological, pharmacological, and pathological states.
The most dramatic demonstrations of the ability of the deoxyglucose method to map functional activity in the CNS have been in the primary visual cortex of the monkey. In this species, as in all animals with binocular vision, the visual pathways are approximately 50% crossed at the optic chiasma. The projections from the two retinas remain segregated and terminate in six well-defined