SOME IMPLICATIONS OF THE STOCHASTIC BEHAVIOR OF PRIMARY AUDITORY NEURONS,
MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS
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Recent electrophysiological studies of the activity in response to acoustic stimuli of single primary afferent neurons in the VIIIth nerve of mammals strongly suggest that the spike activity is inherently stochastic in that a the detailed pattern of activity varies unpredictably from repetition to repetition of an identical acoustic waveform, but b appropriate averages of this activity show stability or statistical regularity. Since the only way in which auditory information can reach the more central parts of the nervous system is via the VIIIth nerve, the effective neural noise implied by such stochastic coding of auditory information must set some sort of limits on auditory discriminations. As shown in this paper, these limits can be calculated if an appropriate statistical model of the neural activity is accepted. Of course, no more than a bound on discrimination performance can be determined in this way, since there is no reason to suppose that the central processing in the nervous system is effectively ideal -- particularly in the artificial situations of auditory psychophysics. But if these bounds closely approximate performance and there is some reason to believe they may, at least for the very simple auditory discriminations treated in this paper then it seems reasonable to maintain that the observed stochastic coding in a sense accounts for or explains these behavioral limits.