The sensitivity of neurons with non-periodic activity to sympathetic stimulation in rat injured dorsal root ganglion.

Objective The relationship between firing pattern and sensitivity of neurons was studied in chronically compressed dorsal root ganglion (DRG) neurons and the Hindmarsh-Rose (HR) neuronal model. Methods Spontaneous activities from single fibers of chronically compressed DRG neurons in rats were recorded, and divided into periodic and non-periodic firing patterns. The sensitivity of the two kinds of firing pattern neuron to sympathetic stimulation (SS) was compared. Result It was found that 27.3% of periodic firing neurons and 93.2% of non-periodic firing neurons responded to SS respectively (periodic vs non-periodic, P < 0.01). The responses to SS with different stimulation time were greater non-periodic firing neurons than periodic firing neurons (P < 0.01). The non-periodic firing neurons obviously responded to SS. After the firing pattern of these neurons transformed to periodic firing pattern, their responses to SS disappeared or decreased obviously. The HR neuronal model exhibited a significantly greater response to perturbation in non-periodic (chaotic) firing pattern than in periodic firing pattern. Conclusion The non-periodic firing neurons with deterministic chaos are more sensitive to external stimuli than the periodic firing neurons.