We introduce a nonlinear dynamical system with self-exciting chaotic dynami
cs. Its interspike interval return mag shows a noisy Poisson-like distribut
ion. Spike sequences from different initial conditions are unrelated but po
ssess the same mean frequency. In the presence of noisy perturbations, sequ
ences started from different initial conditions synchronize. The features o
f the model are compared with experimental results for irregular spike sequ
ences in neurons. Self-exciting chaos offers a mechanism for temporal codin
g of complex input signals.