Representation of time-dependent correlation and recurrence time functions. A new method to analyse non-stationary point processes.

Correlation functions based on time averaging are not suited to study non-stationary point processes (e.g. the electric organ discharge activity of weakly-electric pulse fish). To overcome this problem, we present here a time-dependent correlation method, which can also be applied to study complicated correlations of moderately non-stationary point processes (e.g. neuronal spike trains). Indication of recurrence time aspects of the point processes provides a more complete representation of the correlation functions. In addition higher order correlations between two point processes are represented.