[Spectrum analysis of cat si neurone discharges]

Spontaneous firing and the discharges evoked by A- and/or C-fiber inputs (A-ED, C-ED, AC-ED) of saphenous nerve were recorded in the somatosensory cortical (SI) neurons (n = 128) of the cats anesthetized with chloralose and paralysed by gallamine. Normalized power spectrum density function (NPSDF) was used to analyse the neuron discharges. The results showed that 1) all the NPSDFs for the spontaneous discharges were single-peak with a peak frequency of 3.91 +/- 1.63 Hz (spontaneous rhythm) and a peak value of 0.0154 +/- 0.0045; 2) the NPSDFs of A-ED showed a single peak (peak value 0.021 +/- 0.0054) and an overlapped double-peak (with spontaneous discharge) or a separate multi-peak (without spontaneous discharge); 3) the NPSDFs of C-ED showed a single peak (peak value 0.020 +/- 0.007) or a separate double-peak; 4) the NPSDFs of AC-ED have two patterns: a single peak (peak value 0.023 +/- 0.004) and an overlapped multi-peak. It is suggested that A-fiber input can potentiate the rhythms of the spontaneous discharge and induce specific rhythm; that C-fiber input can potentiate the spontaneous rhythm and induce characteristic C-rhythm. It is also observed that both spontaneous rhythm and evoked rhythm affect each other; that the evoked rhythms by A-fiber and C-fiber inputs also affect each other.