Serial Dependency in the Discharge Patteirn of Dorsal Spinocerebellar Tract Neurons: A Computer Simulation Analysis

Abstract

We have developed a model in order to analyze the factors eventually responsible for the strong negative serial dependency between successive interspike intervals in the discharge of the Dorsal Spinocerebellar Tract (DSCT) neurons. This dependency is reflected, phenomenologically, by short intervals followed by long ones and, quantitatively, by the first order correlation coefficient (R_1–2); which can be lower than —. 6 (Jansen, Nicolaysen & Rudjord, 1966; Kröller and Grüsser, 1982). We have found that the lowest values of R_1–2 are always related with model parameter values which were very similar to those obtained experimentally. It was observed that the EPSP amplitude distribution plays an important role in the discharge patrerns of the DSCT neurons. There is one fiber that elicits EPSPs greater than 6mV, which is responsible for the genesis of the short intervals in the discharge. Long intervals are determined basically by a suprathreshold depolarization and the afterhyperpolarization processes.

Key Words:

• Dorsal Spinocerebellar Tract neurons
• neuronal models
• serial dependency
• neuronal discharge patterns
• information transmission
• computer simulation