Operating Frequency of Spontaneous Activity Recorded in the Cat Spinal Cord

It has been proposed that different electrophysiological recordings (ECG, EMG or EEG) maintain a similar energy distribution among themselves, regardless of the position of the electrode monitoring the activity of a relatively large or small set of excitable cells. The aim of the present study is to establish a frequency of capture of electrophysiological recordings that is suitable for the analysis of spontaneous activity recorded from the dorsum of the cat spinal cord (ADM). The recordings analyzed were obtained with sampling frequencies 1.66 KHz, 5 KHz and 10 KHz, in separate experiments. Our observations show that sampling frequencies above 5 KHz and below 156 Hz cause a significant loss of information. Based on the Nyquist theorem, the capture frequency should be at least twice the operating frequency. To determine the operating frequency of neuronal clusters in the spinal cord, we used both the IFS method to generate fractals from the electrophysiological signals, the Fractal Dimension (using the box method) and the DFA to find the most appropriate frequency. With the methods used, we found that the fractal dimension varies significantly (from 1.25 to 0.71), depending on the capture frequency. According to our results, it can be proposed that frequencies in the range 550 to 1250Hz are the most suitable for capturing the activity of neuronal clusters in the spinal cord.