The High Frequency Discharge of Pallidal Neurons Disrupts the Interpretation of Pallidal Correlation Functions

A fundamental tool in electrophysiological research is correlation. The autocorrelation function, which describes the probability that a neuron will emit a spike as a function of the time elapsed from another firing of a spike by that neuron, is an important step in the understanding of the cell's intrinsic firing pattern (Perkel et al. 1967). Calculation of the cross-correlation function, on the other hand, is a major tool for examining interaction between multiple cells. The cross-correlation function describes the probability that a neuron will emit a spike as a function of the time elapsed from the firing of a spike by a second neuron (Perkel et al. 1967). Both of these methods have been used extensively to assess firing characteristics and functional connectivity of neurons within the basal ganglia (Groves et al. 1978; Stern et al. 1998), and specifically within the pallidum (Nini et al. 1995; Raz et al. 2000). The results obtained from these methods drive our understanding of the firing properties of the pallidum in health and disease.