The cat was used as the experimental animal, and ganglia of some Mollusc species were used to treat some basic questions at the neuronal level. The main techniques were surgical, electrophysiological, pharmacological, and histological. Learning, as a behavioral feature, presupposes underlying nervous processes for association of sensory messages, as well as appropriate functional links between the associative operations and those to which they give rise on the efferent side, viz: ...