Conditional cross-interval correlation analyses with applications to simultaneously recorded cerebellar Purkinje neurons

Two conditional cross-correlation techniques are described for the analysis of two simultaneously recorded neuronal spike trains. The conditional interspike interval histogram describes the distribution of interspike intervals of a neuron conditioned by a preceding spike in another neuron. The conditional cross-internal histogram describes the distribution of cross-intervals of two neurons conditioned by a preceding spike in one of the neurons. These techniques could be used to reveal the temporal coupling in the discharge of two neurons recorded simultaneously. The techniques augment the description of the correlation obtained with conventional cross-correlation measures. When applied to the simple spike discharge of simultaneously recorded cerebellar Purkinje neurons, the methods reveal temporal interactions between neurons that are not readily apparent from conventional cross-correlograms. The patterns observed suggest a tightly coupled, temporal surround-inhibition among nearby Purkinje neurons.