Relationship among discharges of neighboring neurons in the rat prefrontalcortex during spatial working memory tasks

The relationship among discharges of neurons that were recorded simultaneou sly with tetrodes in the rat medial prefrontal cortex was analyzed. Spatial working memory tasks were divided into several distinct stages based on th e behavioral correlates of individual neurons, and interneuronal correlatio n of signal (mean discharge rate at each stage) and noise (trial-to-trial d eviation from the signal) was calculated. Behavioral correlates of neighbor ing neurons were quite heterogeneous and, accordingly, average signal corre lation was relatively low (similar to 0.16). Noise correlation was even low er (similar to 0.06), but neuronal noise was more correlated among the neur ons with similar signals. Spikes underlying the signal and noise correlatio n among the prefrontal cortical neurons were loosely synchronized over a fe w hundred milliseconds. These results suggest that neighboring prefrontal c ortical neurons process largely independent information and have weakly cor related noise and that precisely synchronized spikes play a relatively mino r role in producing the correlated signal and noise among these neurons.