FREQUENCY AND BURST DURATION IN OSCILLATING NEURONS AND 2-CELL NETWORKS

We study the relationship of injected current to oscillator period in single neurons and two-cell model networks formed by reciprocal inhibi tory synapses. Using a Morris-Lecar-like model, we identify two qualit ative types of oscillatory behavior for single model neurons. The ''cl assical'' oscillator behavior is defined as type A. Here the burst dur ation is relatively constant and the frequency increases with depolari zation. For oscillator type B, the frequency first increases and then decreases when depolarized, due to the variable burst duration. Our si mulations show that relatively modest changes in the maximal inward an d outward conductances can move the oscillator from one type to anothe r. Cultured stomatogastric ganglion neurons exhibit both A and B type behaviors and can switch between the two types with pharmacological ma nipulation. Our simulations indicate that the stability of a two-cell network with injected current can be extended with inhibitory coupling . In addition, two-cell networks formed from type A or type B oscillat ors behave differently from each other at lower synaptic strengths.