Rate fluctuations and fractional power-law noise recorded from cells in the lower auditory pathway of the cat.
The noise properties of the sequence of action potentials recorded from adult-cat auditory nerve fibers and lateral superior olivary units have been investigated under various stimulus conditions. Large fluctuations exhibited by the spike rate, and spike clusters evident in the pulse-number distribution, both indicate an unusual underlying sequence of neural events. We present results demonstrating that (i) the firing rate calculated with different averaging times can exhibit self-similar behavior; (ii) the pulse-number distribution remains irregular even for large numbers of samples; (iii) the spike-number variance-to-mean ratio increases with the counting time T in fractional power-law fashion for sufficiently large T; and (iv) the exponent in the power law generally depends on the stimulus level. The results obtained in our laboratories support the notion that all auditory-nerve and LSO units exhibit fractal neural firing patterns, as indicated earlier by Teich (IEEE Trans. Biomed. Eng. 36, 150-160, 1989).
Teich
M C
MC
Department of Electrical Engineering, Columbia University, New York, New York 10027.
Johnson
D H
DH
Kumar
A R
AR
Turcott
R G
RG
D000200:Action Potentials; D000818:Animals; D001306:Auditory Pathways; D002415:Cats; D009412:Nerve Fibers / Q000502:physiology; D009622:Noise; D009847:Olivary Nucleus / Q000502:physiology*; D000159:Vestibulocochlear Nerve / Q000502:physiology*