Complex dynamics of neuronal thresholds

We study an integrate and fire model of an adapting neuron. Using two dynam ic thresholds, we account for the complex long-term behavior of single neur ons under periodic pulsed inputs. We find that the pattern of temporal resp onse is that of a staircase of inter-spike interval values. The characteris tic time scales of transitions between these ISI values are of the order of tens of seconds. The temporal behavior of our system can be described as a path through the two-dimensional phase space of dynamic thresholds. (C) 20 00 Elsevier Science B.V. All rights reserved.