Using digital video techniques to identify correlations between behavior and the activity of single neurons

Digital movies were made of freely behaving rats in a cylinder. At the same time, action potentials were recorded from single hippocampal neurons. We describe a data processing scheme that allows the spike data and the movie to be merged. A display of the ongoing unit activity was added to each frame in the movie. This provided a powerful new way to examine the relationships between behavior and spike discharge. A second type of data processing, activity-edited video identified and used interesting episodes of neuronal activity (e.g. fast firing) to select the corresponding frames from the original movie. The activity-edited movie can then be viewed to look for behavioral invariances during the episodes that were selected according to the cell's firing rate. The feasibility of these methods was tested by applying them to post-subicular head direction cells and hippocampal place cells because these cell classes have well characterized behavioral correlates. The digital video techniques captured the head direction and place cell phenomena and provided a novel and robust description of the relationship between the firing of these cells and the overall behavior of the rat.