Temporal Properties of Responses to Broadband Noise in the Auditory Nerve

2004 ◽  
Vol 91 (5) ◽  
pp. 2051-2065 ◽  
Author(s):  
Dries H. G. Louage ◽  
Marcel van der Heijden ◽  
Philip X. Joris
Keyword(s):  
Fourier Analysis ◽  
Auditory Nerve ◽  
Phase Locking ◽  
Strong Dependence ◽  
Peak Height ◽  
Nerve Fibers ◽  
Broadband Noise ◽  
Temporal Information ◽  
Temporal Behavior ◽  
Locking Range

Temporal information in the responses of auditory neurons to sustained sounds has been studied mostly with periodic stimuli, using measures that are based on Fourier analysis. Less information is available on temporal aspects of responses to nonperiodic wideband sounds. We recorded responses to a reference Gaussian noise and its polarity-inverted version in the auditory nerve of barbiturate-anesthetized cats and used shuffled autocorrelograms (SACs) to quantify spike timing. Two metrics were extracted from the central peak of autocorrelograms: the peak-height and the width at halfheight. Temporal information related to stimulus fine-structure was isolated from that to envelope by subtracting or adding responses to the reference and inverted noise. Peak-height and halfwidth generally behaved as expected from the existing body of data on phase-locking to pure tones and sinusoidally amplitude-modulated tones but showed some surprises as well. Compared with synchronization to low-frequency tones, SACs reveal large differences in temporal behavior between the different classes of nerve fibers (based on spontaneous rate) as well as a strong dependence on characteristic frequency (CF) throughout the phase-locking range. SACs also reveal a larger temporal consistency (i.e., tendency to discharge at the same point in time on repeated presentation of the same stimulus) in the responses to the stochastic noise stimulus than in the responses to periodic tones. Responses at high CFs reflect envelope phase-locking and are consistent with previous reports using sinusoidal AM. We conclude that the combined use of broadband noise and SAC analysis allow a more general characterization of temporal behavior than periodic stimuli and Fourier analysis.

Response Properties of Single Auditory Nerve Fibers in the Mouse

2005 ◽  
Vol 93 (1) ◽  
pp. 557-569 ◽  
Author(s):  
Annette M. Taberner ◽  
M. Charles Liberman
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Phase Locking ◽  
Nerve Fibers ◽  
Cochlear Function ◽  
Response Properties ◽  
Tuning Curves ◽  
Rate Versus ◽  
Interstrain Difference ◽  
Mutant Lines

The availability of transgenic and mutant lines makes the mouse a valuable model for study of the inner ear, and a powerful window into cochlear function can be obtained by recordings from single auditory nerve (AN) fibers. This study provides the first systematic description of spontaneous and sound-evoked discharge properties of AN fibers in mouse, specifically in CBA/CaJ and C57BL/6 strains, both commonly used in auditory research. Response properties of 196 AN fibers from CBA/CaJ and 58 from C57BL/6 were analyzed, including spontaneous rates (SR), tuning curves, rate versus level functions, dynamic range, response adaptation, phase-locking, and the relation between SR and these response properties. The only significant interstrain difference was the elevation of high-frequency thresholds in C57BL/6. In general, mouse AN fibers showed similar responses to other mammals: sharpness of tuning increased with characteristic frequency, which ranged from 2.5 to 70 kHz; SRs ranged from 0 to 120 sp/s, and fibers with low SR (<1 sp/s) had higher thresholds, and wider dynamic ranges than fibers with high SR. Dynamic ranges for mouse high-SR fibers were smaller (<20 dB) than those seen in other mammals. Phase-locking was seen for tone frequencies <4 kHz. Maximum synchronization indices were lower than those in cat but similar to those found in guinea pig.

Pathophysiology of Tinnitus

1984 ◽  
Vol 93 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Aage R. Møsller
Keyword(s):  
Auditory Nerve ◽  
Neural Coding ◽  
Temporal Pattern ◽  
Phase Locking ◽  
Cranial Nerves ◽  
Nerve Fibers ◽  
Complex Sounds ◽  
Ephaptic Transmission ◽  
Recent Developments ◽  
Auditory Nerve Fibers

The hypothesis is presented that certain forms of tinnitus are related to abnormal phase-locking of discharges in groups of auditory nerve fibers. Recent developments in auditory neurophysiology have shown that neural coding of the temporal pattern of sounds plays an important role in the analysis of complex sounds. In addition, it has been demonstrated that when some other cranial nerves are damaged, artificial synapses can occur between individual nerve fibers such that ephaptic transmission between nerve fibers is facilitated. Such “crosstalk” between auditory nerve fibers is assumed to result in phase-locking of the spontaneous activity of groups of neurons which in the absence of external sounds creates a neural pattern that resembles that evoked by sounds.

scholarly journals Response Growth With Sound Level in Auditory-Nerve Fibers After Noise-Induced Hearing Loss

2004 ◽  
Vol 91 (2) ◽  
pp. 784-795 ◽  
Author(s):  
Michael G. Heinz ◽  
Eric D. Young
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Auditory Nerve ◽  
Outer Hair Cell ◽  
Dynamic Range ◽  
Nerve Fibers ◽  
Sound Level ◽  
Broadband Noise ◽  
Noise Induced Hearing Loss ◽  
Rate Level

People with sensorineural hearing loss are often constrained by a reduced acoustic dynamic range associated with loudness recruitment; however, the neural correlates of loudness and recruitment are still not well understood. The growth of auditory-nerve (AN) activity with sound level was compared in normal-hearing cats and in cats with a noise-induced hearing loss to test the hypothesis that AN-fiber rate-level functions are steeper in impaired ears. Stimuli included best-frequency and fixed-frequency tones, broadband noise, and a brief speech token. Three types of impaired responses were observed. 1) Fibers with rate-level functions that were similar across all stimuli typically had broad tuning, consistent with outer-hair-cell (OHC) damage. 2) Fibers with a wide dynamic range and shallow slope above threshold often retained sharp tuning, consistent with primarily inner-hair-cell (IHC) damage. 3) Fibers with very steep rate-level functions for all stimuli had thresholds above approximately 80 dB SPL and very broad tuning, consistent with severe IHC and OHC damage. Impaired rate-level slopes were on average shallower than normal for tones, and were steeper in only limited conditions. There was less variation in rate-level slopes across stimuli in impaired fibers, presumably attributable to the lack of suppression-induced reductions in slopes for complex stimuli relative to BF-tone slopes. Sloping saturation was observed less often in impaired fibers. These results illustrate that AN fibers do not provide a simple representation of the basilar-membrane I/O function and suggest that both OHC and IHC damage can affect AN response growth.

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