Preliminary Studies of the Development of the Cholinergic System in the Visual Cortex

Abstract

While much is known of the noradrenergic and serotenergic systems within the central nervous system (CNS), the cholinergic and its development remain relatively ambiguous. A project was begun in which cholinergic cells in the visual cortex were studied using electrophysiological techniques. A metal electrode was inserted in one barrel of a five-barrel glass pipette in order to record activity of single neurons in the cortex while the other barrels were used to apply cholinergic drugs using microiontophoretic techniques. The electrode was inserted in the cortex of paralyzed, anesthetized adult cats and neuronal activity observed. Cells were classified according to the Hubel and Weisel system for simple and complex cells and the system of Kato, Bishop and Orban to determine hypercomplexity. The effect of the drug on the response of a single neuron to visual stimulation was studied and the cholinergic system characterized. It was found that the results lended support to a model of parallel processing of information in the brain. Ultimately, comparisons of cells in adult cats and of cells in kittens will reveal important aspects of the development of the cholinergic system in the mammalian CNS.