Israel J. of Med. Sci. 32:S22. (1996).
In this work we combine analytical studies and numerical simulations to investigate the role of spike adaptation in collective dynamics. The model neurons fire tonically with constant input and cannot produce burst. We show that with realistic strength and time scale of the adaptation the network settles into a state in which the neurons {\it burst} synchronously. This is in contrast with what happens in the absence of adaptation where it has been shown recently that it is hard to get rhythmic network activity for comparable excitatory interactions. We characterize the transition from the asynchronous tonically firing regime to the synchronized bursting state when adaptation is increased. We show that beyond this transition, although the bursts are synchronized the spikes within bursts are not. We demonstrate that this state is the result of a "conspiracy" between the adaptation and the network feedback. We study the properties of the emerging rhythm and its stability against variation of the interactions parameters and input strength. We show that the period of the rhythm depends mainly on the adaptation time constant while the burst duration depends on the strength of the adaptation, the input and the synaptic interaction. This collective state is established within the first burst following the stimulating input which for physiological cellular and network parameters is of the order of 100msec.
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