Nonlinear Neural Dynamics in Olfaction as a Model for Cognition

Abstract

The forebrain of primitive vertebrates is so heavily devoted to olfaction that for half a century investigators were misled into considering the function of the hippocampus as being exclusively olfactory. For example, the anterior third of the forebrain of the tiger salamander forms the bulb, the medial third is hippocampus, and the lateral third comprises the piriform and striato-amygdaloid complex (Herrick 1948). According to Herrick, a transitional zone in the mantel receives thalamic axons that convey input to the forebrain from all other sensory systems. He proposed that with the expansion and increasing dominance of these other systems, the brain expanded by adding new parts while preserving the topology of connections of those parts already existing. This view has survived to the present with modifications; it is as if, seeing that olfaction was a success, other systems moved in and co-opted the machinery of the forebrain. Olfaction remains the simplest among the sensory systems. For this reason, if for no other, the study of sensation and cognition might well begin with the sense of smell. But there are three other good reasons: the parallels that exist between olfaction and other senses in their psychophysics, in the dynamics of the masses of neurons comprising them, and in the types of neural activity that they generate.

Originally published in Başar E (ed) Dynamics of sensory and cognitive processing by the brain. Springer, Berlin Heidelberg New York, pp 19-29 (Springer series in brain dynamics, vol 1). Cross references refer to that volume.