ABSTRACT
Many previous studies have shown that auditory cortical neurons are sensitive to sound spatial information, however, the mechanism of sound spatial coding is still not fully understood. Until now, detail studies on sound spatial coding have not been reported in the rat primary auditory cortex. Using electrophysiological technique, spatial response areas of 151 neurons in the rat primary auditory cortex were investigated. The relationships between spike counts and average first-spike latencies in the spatial response areas were analyzed. The results showed that, the majority (52.32%) of cortical neurons exhibited contralateral preference in the frontal auditory space whereas other neurons exhibited ipsilateral preference (18.54%) and midline preference (18.54%), and only a few neurons were included in the category of omnidirection (3.31%) and complex (7.28%). For the majority of cortical neurons, the arithmetic center of the preferred spatial area were distributed in the up and middle portion of the contralateral space relative to the recording side. Most neurons responded strongly to stimuli from their preferred space with shorter average first-spike latencies, and responded weakly to stimuli from non-preferred space with longer average latencies. In the spatial response area, the spike counts were negatively correlated with average first-spike latencies. The auditory cortex might use the information of both spike counts and average response time to code sound spatial information.