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Methods of statistical physics have been recently successfully ap- plied to the study of spatial ánd temporal randomness in various biological systems, like the analýsts of the DNA nucleotide sequences and the heartbeat time series. We study the interspike intervals (ISI) time series of the spinal dorsal horn nociceptive- responsive neurons (DHN) activity in decerebrate cats applying the detrended fluctuatìon analysis (DFA) that is a modification of the standard random walk model analysis. Specifically, we focus on ISI variability as an important quantity to help elucidate sensory coding and signal processing performed by DHN. DFA has been applied for it permtts quantification of correlation properties of a nonstationary time series of neuronal discharge, Changes in DHN activity were extracellularly recorded with high impedance glass microelectrodes from superficial laminae of the dorsal horn, during different experimentally simúlated conditions. We háve analyzed DHN discharge patterns during spontaneous activity, as well as in the presence of diflerent noxious and non- noxious mechanical stimuli. Application of DFA method showed significant changes in dynamics of neural discharge when the ex- ternal stimulus is appliéd. These findings demonstrate the relevance of the application of methods of statistical. physics to identify the changes in aflerent inflow, and to characterize temporal patterns of activity of neurons under study