Abstract
We have investigated dynamics of single neuronal spontaneous activities in the mesencephalic reticular formation (MRF) of a cat in natural outdoors, using a telemetry system that could measure 7 channels of physiological signals, such as neuronal activity, electroencephalogram, electrooculogram, electromyo gram, and so on. The telemetry system transmits the signals by the method of PDM/FM with about 88MHz of main carrier. We have successfully recorded long-term spike trains of several single neurons in the MRF. Spectral analyses were carried out on the time series of counts converted from the spike train. The spectrum during waking state outdoors showed a spectral density approximately inversely proportional to frequency (1/f-like spectrum) in the frequency range of 0.01-1.0Hz. The 1/f-like spectral characteristic during waking state was similar to the one during paradoxical sleep, but clearly different from the white-noise-like spectral profile during slow wave sleep. The 1/f-like spectra observed in the MRF neuronal activities outdoors probably suggest that the neuronal activity displays slow fluctuations both by inputs from the internal/external environments and by dynamics of the MRF neuronal network.
