Rhythmic Pattern And Rules Of Dynamic Variations In Spontaneous Discharge Of Injured Dorsal Root Ganglion Neurons

The main function of nervous system is to collect, process and store information from both the internal and external environments, and respond with appropriate reactions. Neural information is conveyed along nerve fibers in the form of series of propagating action potentials. Peripheral information can be coded by the sensory nervous system into neural signals that can be perceived by the brain. The concept of rate coding of neural signals has been accepted for nearly a century, to the extent that most pursuers of the notion took it as the only criterion for the abundance of neural signals. But in recent years the rate coding theory has met with many difficulties in attempting to explain the encoding, transfer and decoding of neural signals. Hence the temporal pattern of nerve discharge has been attracting the attention of many researchers in this field. If the temporal pattern of neuronal discharge does encode neural signals, then it is imperative to have a concrete and thorough understanding of the processes involved. Thus we adopt the model of chronic compression of dorsal root ganglion to study the basic rhythmic pattern and the rule(s) of transition in neuronal discharge patterns. The DRG neuron of this model can generate spontaneous discharges with diverse patterns and multiple rhythms, coupled with the lack of complicated neural network among peripheral neurons, it thus poses an ideal model to study neural discharge coding.The present work was therefore designed to record single unit discharging from afferent fibers of DRG neuron, collect the interspike interval (ISI) sequence of neuronal discharges, sum and analyze, the rhythmic pattern of neuronal discharges, and finally perfuse the injured DRG neuron with different potassium channel blockers in order to identify the underlying dynamic rules of variations in the rhythmic patterns of neuronal discharges.The main results are as follows:1. Five patterns of spontaneous discharge rhythms were encountered during recording of 120 injured DRG neurons. Based on the dynamic features of ISI series, these patterns were classified into ①periodic rhythm, ② integer multiples rhythm, ③slow wave oscillatory rhythm, ④bursting rhythm and ⑤irregular rhythm. One characteristic of integer multiples rhythm lies in it's...