A MODEL FOR TEMPORAL AND INTENSITY CODING IN INSECT OLFACTION BY A NETWORK OF INHIBITORY NEURONS

Female insects release sex-pheromones which attract their conspecific males. These pheromones are detected through a distinct male-specific olfactory subsystem which resides at the first stage of olfactory proc essing, and consists of receptor, local and projection (relay) neurons . When male insects were stimulated by female sex-pheromones, some pro jection neurons could distinguish between different pheromones, follow ing input and code stimulus intensity. Presented here, is a simple bio physical model that described characteristic bursting responses observ ed for projection neurons. The bursting behavior of the model resulted from a particular cellular mechanism and specific network architectur e. At the neuron level, a rapidly activating and slowly inactivating l ow-threshold calcium channel provided depolarizing current for burstin g, while at the network level, inhibitory neurons implementing dis-inh ibition which triggered this calcium channel. Also, the network archit ecture provided a mechanism by which certain projection neurons coded temporal input and stimulus intensity.