Single-tone intensity discrimination based on auditory-nerve rate responses in backgrounds of quiet, noise, and with stimulation of the crossed olivocochlear bundle

We use simple statistical models of the firing patterns of high, medium, and low spontaneous rate auditory-nerve fibers to study mechanisms which determine the overall dynamic range of the auditory periphery. The models relate experimentally measured rate response properties of fibers with best frequency (BF) near 8.0 kHz to their ability to encode changes in BF tone level by changes in discharge rate in backgrounds of quiet and noise, with and without electrical stimulation of the crossed olivocochlear bundle (COCB). Application of the models to the BF tone rate responses of auditory-nerve fibers in backgrounds of quiet shows that optimum processing of the rate responses of fibers with BF near 8.0 kHz yields performance in the intensity discrimination task meeting or exceeding that of human subjects over an 80 dB range of levels. By defining a statistical measure of dynamic range, we confirm the results of Costalupes et al. (1984) demonstrating that masking noise shifts the dynamic range of auditory-nerve fibers to higher stimulus levels, thus preventing rate saturation. However, model analysis shows that masking noise also produces large reductions of dynamic range as well as large increases in the minimum intensity difference that can be encoded by the rate responses of single and ensembles of fibers. Electrical stimulation of the COCB can restore auditory-nerve fiber dynamic range and sensitivity to changes in BF tone level in noise backgrounds, in some cases to roughly that observed in backgrounds of quiet.

[1]  M. Liberman.  Morphological differences among radial afferent fibers in the cat cochlea: An electron-microscopic study of serial sections , 1980, Hearing Research.

[2]  R. Smith.  Short-term adaptation in single auditory nerve fibers: some poststimulatory effects. , 1977 .

[3]  W. S. Rhode.  Observations of the vibration of the basilar membrane in squirrel monkeys using the Mössbauer technique. , 1971, The Journal of the Acoustical Society of America.

[4]  B C Moore,et al.  Intensity discrimination: a severe departure from Weber's law. , 1984, The Journal of the Acoustical Society of America.

[5]  D H Johnson,et al.  Analysis of discharges recorded simultaneously from pairs of auditory nerve fibers. , 1976, Biophysical journal.

[6]  W. Dixon Ward,et al.  Temporary Threshold Shift with Changing Duty Cycle , 1962 .

[7]  E. Allen,et al.  Behavioral auditory function after transection of crossed olivo-cochlear bundle in the cat. V. Pure-tone intensity discrimination. , 1979, Acta oto-laryngologica.

[8]  W. Warr.  Olivocochlear and vestibular efferent neurons of the feline brain stem: Their location, morphology and number determined by retrograde axonal transport and acetylcholinesterase histochemistry , 1975, The Journal of comparative neurology.

[9]  E D Young,et al.  Effects of continuous noise backgrounds on rate response of auditory nerve fibers in cat. , 1984, Journal of neurophysiology.

[10]  E. Evans,et al.  Intensity coding in the auditory periphery of the cat: Responses of cochlear nerve and cochlear nucleus neurons to signals in the presence of bandstop masking noise , 1982, Hearing Research.

[11]  EFFECT OF COCHLEAR LESIONS UPON AUDIOGRAMS AND INTENSITY DISCRIMINATION IN CATS. , 1965 .

[12]  N. Viemeister,et al.  Auditory intensity discrimination at high frequencies in the presence of noise. , 1983, Science.

[13]  M. Wiederhold.  Variations in the effects of electric stimulation of the crossed olivocochlear bundle on cat single auditory-nerve-fiber responses to tone bursts. , 1970, The Journal of the Acoustical Society of America.

[14]  R. Muirhead.  Aspects of Multivariate Statistical Theory , 1982, Wiley Series in Probability and Statistics.

[15]  M. Liberman.  The cochlear frequency map for the cat: labeling auditory-nerve fibers of known characteristic frequency. , 1982, The Journal of the Acoustical Society of America.

[16]  M. Igarashi,et al.  Behavioral auditory function after transection of crossed olivo-cochlear bundle in the cat. I. Pure-tone threshold and perceptual signal-to-noise ratio. , 1972, Acta oto-laryngologica.

[17]  D. M. Green,et al.  Intensity discrimination as a function of frequency and sensation level. , 1977, The Journal of the Acoustical Society of America.

[18]  Paul J. Abbas,et al.  Phenomenological model for two‐tone suppression , 1976 .

[19]  Bertrand Delgutte,et al.  Peripheral Auditory Processing of Speech Information: Implications from a Physiological Study of Intensity Discrimination , 1987 .

[20]  M B Sachs,et al.  Nonlinearities in auditory-nerve fiber responses to bandlimited noise. , 1980, The Journal of the Acoustical Society of America.

[21]  Malvin C. Teich,et al.  Dead-time-corrected photocounting distributions for laser radiation* , 1975 .

[22]  E D Young,et al.  Rate responses of auditory nerve fibers to tones in noise near masked threshold. , 1986, The Journal of the Acoustical Society of America.

[23]  J. Guinan,et al.  Effects of crossed-olivocochlear-bundle stimulation on cat auditory nerve fiber responses to tones. , 1983, The Journal of the Acoustical Society of America.

[24]  R L Smith,et al.  Adaptation, saturation, and physiological masking in single auditory-nerve fibers. , 1979, The Journal of the Acoustical Society of America.

[25]  M C Teich,et al.  A neural-counting model incorporating refractoriness and spread of excitation. I. Application to intensity discrimination. , 1979, The Journal of the Acoustical Society of America.

[26]  Don H. Johnson,et al.  The response of single auditory-nerve fibers in the cat to single tones: synchrony and average discharge rate , 1974 .

[27]  John J. Guinan,et al.  Efferent innervation of the organ of corti: two separate systems , 1979, Brain Research.

[28]  Philip E. Gill,et al.  Practical optimization , 1981 .

[29]  Donald L. Snyder,et al.  Random point processes , 1975 .

[30]  M. Sachs,et al.  Effect of electrical stimulation of the crossed olivocochlear bundle on auditory nerve response to tones in noise. , 1987, Journal of neurophysiology.

[31]  M. Liberman,et al.  Auditory-nerve response from cats raised in a low-noise chamber. , 1978, The Journal of the Acoustical Society of America.

[32]  C. Trahiotis,et al.  Behavioral investigation of some possible effects of sectioning the crossed olivocochlear bundle. , 1970, The Journal of the Acoustical Society of America.

[33]  J. Guinan,et al.  Differential olivocochlear projections from lateral versus medial zones of the superior olivary complex , 1983, The Journal of comparative neurology.

[34]  E. Javel,et al.  Suppression of auditory nerve responses I: temporal analysis, intensity effects and suppression contours. , 1981, The Journal of the Acoustical Society of America.

[35]  M. Sachs,et al.  Rate versus level functions for auditory-nerve fibers in cats: tone-burst stimuli. , 1974, The Journal of the Acoustical Society of America.