  Consider a compound Poisson process with jump measure $\nu$ supported by
finitely many positive integers. We propose a method for estimating $\nu$ from
a single, equidistantly sampled trajectory and develop associated statistical
procedures. The problem is motivated by the question whether nerve cells in the
brain exhibit higher-order interactions in their firing patterns. According to
the neuronal assembly hypothesis (Hebb [13]), synchronization of action
potentials across neurons of different groups is considered a signature of
assembly activity, but it was found notoriously difficult to demonstrate it in
recordings of neuronal activity. Our approach based on a compound Poisson model
allows to detect the presence of joint spike events of any order using only
population spike count samples, thus bypassing both the ``curse of
dimensionality'' and the need to isolate single-neuron spike trains in
population signals.
