scholarly journals Time course of dynamic range adaptation in the auditory nerve

2012 ◽  
Vol 108 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Bo Wen ◽  
Grace I. Wang ◽  
Isabel Dean ◽  
Bertrand Delgutte
Keyword(s):  
Firing Rate ◽  
Auditory Processing ◽  
Auditory Nerve ◽  
Time Course ◽  
Dynamic Range ◽  
Rate Adaptation ◽  
Sound Level ◽  
Sound Levels ◽  
Level Function ◽  
Firing Rate Adaptation

Auditory adaptation to sound-level statistics occurs as early as in the auditory nerve (AN), the first stage of neural auditory processing. In addition to firing rate adaptation characterized by a rate decrement dependent on previous spike activity, AN fibers show dynamic range adaptation, which is characterized by a shift of the rate-level function or dynamic range toward the most frequently occurring levels in a dynamic stimulus, thereby improving the precision of coding of the most common sound levels (Wen B, Wang GI, Dean I, Delgutte B. J Neurosci 29: 13797–13808, 2009). We investigated the time course of dynamic range adaptation by recording from AN fibers with a stimulus in which the sound levels periodically switch from one nonuniform level distribution to another (Dean I, Robinson BL, Harper NS, McAlpine D. J Neurosci 28: 6430–6438, 2008). Dynamic range adaptation occurred rapidly, but its exact time course was difficult to determine directly from the data because of the concomitant firing rate adaptation. To characterize the time course of dynamic range adaptation without the confound of firing rate adaptation, we developed a phenomenological “dual adaptation” model that accounts for both forms of AN adaptation. When fitted to the data, the model predicts that dynamic range adaptation occurs as rapidly as firing rate adaptation, over 100–400 ms, and the time constants of the two forms of adaptation are correlated. These findings suggest that adaptive processing in the auditory periphery in response to changes in mean sound level occurs rapidly enough to have significant impact on the coding of natural sounds.

scholarly journals L-type calcium channels refine the neural population code of sound level

2016 ◽  
Vol 116 (6) ◽  
pp. 2550-2563 ◽  
Author(s):  
Calum Alex Grimsley ◽  
David Brian Green ◽  
Shobhana Sivaramakrishnan
Keyword(s):  
Calcium Channels ◽  
Calcium Current ◽  
Dynamic Range ◽  
Sound Level ◽  
Neural Population ◽  
Total Calcium ◽  
Local Networks ◽  
Sound Levels ◽  
Local Circuits

The coding of sound level by ensembles of neurons improves the accuracy with which listeners identify how loud a sound is. In the auditory system, the rate at which neurons fire in response to changes in sound level is shaped by local networks. Voltage-gated conductances alter local output by regulating neuronal firing, but their role in modulating responses to sound level is unclear. We tested the effects of L-type calcium channels (CaL: CaV1.1–1.4) on sound-level coding in the central nucleus of the inferior colliculus (ICC) in the auditory midbrain. We characterized the contribution of CaL to the total calcium current in brain slices and then examined its effects on rate-level functions (RLFs) in vivo using single-unit recordings in awake mice. CaL is a high-threshold current and comprises ∼50% of the total calcium current in ICC neurons. In vivo, CaL activates at sound levels that evoke high firing rates. In RLFs that increase monotonically with sound level, CaL boosts spike rates at high sound levels and increases the maximum firing rate achieved. In different populations of RLFs that change nonmonotonically with sound level, CaL either suppresses or enhances firing at sound levels that evoke maximum firing. CaL multiplies the gain of monotonic RLFs with dynamic range and divides the gain of nonmonotonic RLFs with the width of the RLF. These results suggest that a single broad class of calcium channels activates enhancing and suppressing local circuits to regulate the sensitivity of neuronal populations to sound level.

scholarly journals Dynamic Range Adaptation to Sound Level Statistics in the Auditory Nerve

2009 ◽  
Vol 29 (44) ◽  
pp. 13797-13808 ◽  
Author(s):  
B. Wen ◽  
G. I. Wang ◽  
I. Dean ◽  
B. Delgutte
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Sound Level ◽  
Level Statistics

Leading Inhibition to Neural Oscillation Is Important for Time-Domain Processing in the Auditory Midbrain

2005 ◽  
Vol 94 (1) ◽  
pp. 314-326 ◽  
Author(s):  
Alexander V. Galazyuk ◽  
Wenyu Lin ◽  
Daniel Llano ◽  
Albert S. Feng
Keyword(s):  
Time Domain ◽  
Time Course ◽  
Sound Level ◽  
High Threshold ◽  
Auditory Midbrain ◽  
Response Latencies ◽  
Response Characteristics ◽  
Sound Levels ◽  
Discharge Patterns ◽  
Central Auditory Neurons

A number of central auditory neurons exhibit paradoxical latency shift (PLS), a response characterized by longer response latencies at higher sound levels. PLS neurons are known to play a role in target ranging for echolocating bats that emit frequency-modulated sounds. We recently reported that early inhibition of unit’s oscillatory discharges is critical for PLS in the inferior colliculus (IC) of little brown bats. The goal of this study was to determine in echolocating bats and in nonecholocating animals (frogs): 1) the detailed characteristics of PLS and whether PLS was dependent on sound level, frequency, and duration; 2) the time course of inhibition underlying PLS using a paired-pulse paradigm. We found that 22% of IC neurons in bats and 15% in frogs exhibited periodic discharge patterns in response to tone pulses at high sound levels. The firing periodicity was unit specific and independent of sound level and duration. Other IC neurons (28% in bats; 14% in frogs) exhibited PLS. These PLS neurons shared several response characteristics: 1) PLS was largely independent of sound frequency and 2) the magnitude of shift in first-spike latency was either duration dependent or duration tolerant. For PLS neurons, application of bicuculline abolished PLS and unmasked the unit’s periodical firing pattern that served as the building block for PLS. In response to paired sound pulses, PLS neurons exhibited delay-dependent response suppression, confirming that high-threshold leading inhibition was responsible for PLS. Results also revealed the timing of excitatory and inhibitory inputs underlying PLS and its role in time-domain processing.

Measurement and nature of firing rate adaptation in turtle spinal neurons

2005 ◽  
Vol 191 (7) ◽  
pp. 583-603 ◽  
Author(s):  
R. B. Gorman ◽  
J. C. McDonagh ◽  
T. G. Hornby ◽  
R. M. Reinking ◽  
D. G. Stuart
Keyword(s):  
Firing Rate ◽  
Rate Adaptation ◽  
Spinal Neurons ◽  
Firing Rate Adaptation

Level dependence of cochlear nucleus onset unit responses and facilitation by second tones or broadband noise

1995 ◽  
Vol 73 (1) ◽  
pp. 141-159 ◽  
Author(s):  
I. M. Winter ◽  
A. R. Palmer
Keyword(s):  
Cochlear Nucleus ◽  
Discharge Rate ◽  
Nerve Fibers ◽  
Sound Level ◽  
Spike Timing ◽  
Broadband Noise ◽  
Sound System ◽  
Rate Level ◽  
Sound Levels ◽  
Level Function

1. The responses of onset units in the cochlear nucleus of the anesthetized guinea pig have been measured to single tones, two-tone complexes, and broadband noise (BBN; 20-kHz bandwidth). The onset units were subdivided into three groups, onset-I (OnI), onset-L (OnL), and onset-C (OnC), on the basis of a decision tree using their peristimulus time histogram (PSTH) shape and discharge rate in response to suprathreshold best-frequency (BF) tone bursts. 2. PSTHs were constructed from responses either to single tones at a unit's BF or to BBN as a function of level. When sufficient sustained activity could be elicited from the unit, arbitrarily defined as > 100 spikes/s, a coefficient of variation (CV) was calculated; the majority were characterized by a CV that was similar to transient chopper units (0.35 < CV < 0.5). First spike latency decreased monotonically with increasing sound level. For the majority of onset units, the first spike timing was very precise. 3. BF rate-level functions recorded from OnL and OnC units did not show any signs of discharge rate saturation at the highest sound levels we have used (100-115 dB SPL). No systematic relationship was observed between the threshold at BF and the shape of the rate-level function. BBN rate-level functions were typically characterized by higher discharge rates than in response to BF tones. However, for OnI units and a minority of other onset units, there was little difference in the shape of their rate-level functions in response to BF tones or BBN. 4. The threshold of most onset units to BBN was similar to the threshold to a BF tone that had similar overall root-mean-square (RMS) energy. The BBN threshold was, on average, 5.5 dB greater than the BF threshold. This result contrasts with that found in auditory-nerve fibers recorded in the same species, with the use of an identical sound system, where the threshold to BBN was, on average, 19.4 dB higher. The mean threshold difference between BBN and BF tones for a population of chopper units recorded in the same series of experiments was 17.7 dB. The relative thresholds to BBN and BF tones indicated that the bandwidths near the onset units' BF threshold were broader than could be estimated with the use of single tones. Ten units were characterized by bimodal response areas.(ABSTRACT TRUNCATED AT 400 WORDS)

Firing Rate Adaptation without Losing Sensitivity to Input Fluctuations

2002 ◽  
pp. 180-185 ◽  
Author(s):  
Giancarlo La Camera ◽  
Alexander Rauch ◽  
Walter Senn ◽  
Hans-R. Lüscher ◽  
Stefano Fusi
Keyword(s):  
Firing Rate ◽  
Rate Adaptation ◽  
Firing Rate Adaptation

Antimasking effects of the olivocochlear reflex. II. Enhancement of auditory-nerve response to masked tones

1993 ◽  
Vol 70 (6) ◽  
pp. 2533-2549 ◽  
Author(s):  
T. Kawase ◽  
B. Delgutte ◽  
M. C. Liberman
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Detection Threshold ◽  
Tone Burst ◽  
Nerve Fibers ◽  
Burst Frequency ◽  
Continuous Response ◽  
Discharge Rates ◽  
Burst Intensity ◽  
Level Function

1. The antimasking effects of olivocochlear (OC) efferent feedback were studied in anesthetized or decerebrate cats by comparing responses of single auditory-nerve fibers (ANFs) to tone bursts in continuous masking noise seen with and without addition of a moderate-level contralateral noise known to activate the OC reflex. Responses were measured as a function of tone-burst intensity, tone-burst frequency, and masker intensity and were analyzed so as to allow quantitative estimates of the detectability of the tone bursts against the noise background. 2. Addition of the contralateral OC elicitor both increased the maximum discharge rates to the masked tone bursts and decreased the rates to the ipsilateral masker. The rate increases to the tone bursts could be explained on the basis of a decrease in adaptation caused by decreasing the steady response to the masker. The result is a steepening of the rate-versus-level function for masked tone bursts and a concomitant increase in the estimated discriminability of small increments of tone-burst intensity. 3. For tone bursts at the fiber's characteristic frequency (CF), the OC effects on detection threshold for the masked tone bursts depended on masker level, with small increases in threshold for low masker levels and somewhat larger decreases in threshold for higher masker levels. For tone bursts below CF, OC effects, when present, always decreased the detection threshold. 4. The largest antimasking effects were seen for fibers with CFs between 6 and 12 kHz and for masker levels within 20 dB of the fiber's threshold to the masker. These trends appeared to hold for fibers of all spontaneous rates (SRs). 5. Enhancement of the response to unmasked tone bursts and concomitant decrease in the “spontaneous rate” was elicited by OC activation in fibers if threshold sensitivity approached -10 dB SPL. This “enhancement-in-quiet” appears to arise when an animal-generated noise produces a continuous response (in the absence of purposely applied sound) that is suppressed by OC activity. This finding raises questions as to the range of “true” spontaneous rates in the cat. 6. The results highlight two important distinctions between the effects of OC feedback in quiet versus those in noise. In quiet, the effects are predominately suppressive and are restricted to stimuli at frequencies near a fiber's CF and at intensities within its dynamic range. In continuous background noise, the OC reflex can enhance the responses to transient stimuli. Such effects are seen throughout the fiber's response area.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Midbrain adaptation may set the stage for the perception of musical beat

2017 ◽  
Vol 284 (1866) ◽  
pp. 20171455 ◽  
Author(s):  
Vani G. Rajendran ◽  
Nicol S. Harper ◽  
Jose A. Garcia-Lazaro ◽  
Nicholas A. Lesica ◽  
Jan W. H. Schnupp
Keyword(s):  
Firing Rate ◽  
Cognitive Processes ◽  
Auditory Processing ◽  
Temporal Context ◽  
Present Evidence ◽  
Firing Rates ◽  
Sensory Motor ◽  
Specific Manner ◽  
Musical Rhythms ◽  
Firing Rate Adaptation

The ability to spontaneously feel a beat in music is a phenomenon widely believed to be unique to humans. Though beat perception involves the coordinated engagement of sensory, motor and cognitive processes in humans, the contribution of low-level auditory processing to the activation of these networks in a beat-specific manner is poorly understood. Here, we present evidence from a rodent model that midbrain preprocessing of sounds may already be shaping where the beat is ultimately felt. For the tested set of musical rhythms, on-beat sounds on average evoked higher firing rates than off-beat sounds, and this difference was a defining feature of the set of beat interpretations most commonly perceived by human listeners over others. Basic firing rate adaptation provided a sufficient explanation for these results. Our findings suggest that midbrain adaptation, by encoding the temporal context of sounds, creates points of neural emphasis that may influence the perceptual emergence of a beat.

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