[Comparison of cholinergic systems in Ep neocortical regions of cats with high and low cognitive ability]

Cats were behaviorally tested for the ability to solve the abstraction and generalization tasks. Fractions of light (C) and heavy (D) synaptosomes of the associative temporal (Ep) areas were prepared, and subfractions of synaptic membranes and synaptoplasm were isolated. Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activity and the content of protein and protein sulphydric (SH-) groups were measured in synaptic subfractions. All the studied characteristics were lower in subfractions C of cats with higher cognitive abilities. In subfractions D, the ChAT activity was correlated neither with ChAT activity in the respective C fraction, nor with cognitive abilities of cats. It is suggested that cholinergic terminals originating from neurons of the basal magnocellular nuclei are concentrated in the C fractions, and those from the cortical cholinergic neurons are concentrated in the D fractions. Physiological significance of the "deficiency" of cholinergic inputs of the Ep areas from the basal magnocellular nuclei in animals with higher cognitive abilities is discussed.