Odour recognition and segmentation by a model olfactory bulb and cortex

We present a model of an olfactory system that performs odour segmentation. Based on the anatomy and physiology of natural olfactory systems, it consi sts of a pair of coupled modules, bulb and cortex. The bulb encodes the odo ur inputs as oscillating patterns. The cortex functions as an associative m emory: when the input from the bulb matches a pattern stored in the connect ions between its units, the cortical units resonate in an oscillatory patte rn characteristic of that odour. Further circuitry transforms this oscillat ory signal to a slowly varying feedback to the bulb. This feedback implemen ts olfactory segmentation by suppressing the bulbar response to the pre-exi sting odour, thereby allowing subsequent odours to be singled out for recog nition.