We propose a class of counting process models for analyzing firing tim
es of an ensemble of neurons. We allow the counting process intensitie
s to be unspecified: unknown functions of the times passed since the m
ost recent firings. Under this assumption we derive a class of statist
ics with their respective thresholds as well as graphical meth ods for
detecting neural connectivity. We introduce a model under which detec
tion is shown to be certain for long series of observations. We sugges
t ways to classify interactions as inhibition or excitation and to est
imate their strengths. The power of the proposed methods is compared b
y simulating observations from artificial networks. By analyzing empir
ically obtained series we obtain results which are consistent with tho
se obtained from cross-correlation-based methods but in addition obtai
n new insights on further aspects of the interactions.