Using time difference analysis algorithms to measure the response time of rat auditory cortex neurons to auditory nerve stimulation

Abstract

Measurement of the information flow along the ascending auditory pathway from the periphery to the auditory cortex (AC) has been given much attention in neurocomputation. While the neurophysiological mechanisms of the auditory pathway have been well studied, the temporal resolution and relationships among the auditory centers are still under investigation, especially when suffering from acoustic trauma that results in peripheral deficits and neural signal changes in the auditory system. In this study, we measured rat AC neurons and auditory nerve (AN) signals in digital format by using two new algorithms to calculate the neural response time of the AC neurons to electrical stimulation of the AN and quantify the neural information flow in the temporal domain. One algorithm compared time difference of neural spikes directly, which was based on the conventional idea of spike train in neurocomputation. The other employed a modified cross-correlation algorithm. Both algorithms shared the same pre-signal processing of spike selection. The statistical results by the two methods were compared and various parameters in the algorithms and their impact on the accuracy of the results were discussed. To test the effectiveness of the proposed method, the time difference between the AC to AN activities was calculated by both algorithms with raw neural signals collected. The neural signals from the animals were measured before and after noise trauma, and one of the animals received intra-modiolus electrical stimulation (IMES) to stimulate the AN. The results from using the two algorithms were generally consistent, and the biological mechanisms behind the time delay results between AC and AN activities were discussed.