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

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.

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Temporally selective processing of communication signals by auditory midbrain neurons

Journal of Neurophysiology ◽

10.1152/jn.00261.2009 ◽

2011 ◽

Vol 105 (4) ◽

pp. 1620-1632 ◽

Cited By ~ 23

Author(s):

Taffeta M. Elliott ◽

Jakob Christensen-Dalsgaard ◽

Darcy B. Kelley

Keyword(s):

Temporal Structure ◽

Receptive Fields ◽

Dominant Frequency ◽

Torus Semicircularis ◽

Auditory Midbrain ◽

Communication Signals ◽

Sound Levels ◽

Dorsal Medullary Nucleus ◽

Discharge Patterns ◽

Vocal Signaling

Perception of the temporal structure of acoustic signals contributes critically to vocal signaling. In the aquatic clawed frog Xenopus laevis, calls differ primarily in the temporal parameter of click rate, which conveys sexual identity and reproductive state. We show here that an ensemble of auditory neurons in the laminar nucleus of the torus semicircularis (TS) of X. laevis specializes in encoding vocalization click rates. We recorded single TS units while pure tones, natural calls, and synthetic clicks were presented directly to the tympanum via a vibration-stimulation probe. Synthesized click rates ranged from 4 to 50 Hz, the rate at which the clicks begin to overlap. Frequency selectivity and temporal processing were characterized using response-intensity curves, temporal-discharge patterns, and autocorrelations of reduplicated responses to click trains. Characteristic frequencies ranged from 140 to 3,250 Hz, with minimum thresholds of −90 dB re 1 mm/s at 500 Hz and −76 dB at 1,100 Hz near the dominant frequency of female clicks. Unlike units in the auditory nerve and dorsal medullary nucleus, most toral units respond selectively to the behaviorally relevant temporal feature of the rate of clicks in calls. The majority of neurons (85%) were selective for click rates, and this selectivity remained unchanged over sound levels 10 to 20 dB above threshold. Selective neurons give phasic, tonic, or adapting responses to tone bursts and click trains. Some algorithms that could compute temporally selective receptive fields are described.

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Time course of dynamic range adaptation in the auditory nerve

Journal of Neurophysiology ◽

10.1152/jn.00055.2012 ◽

2012 ◽

Vol 108 (1) ◽

pp. 69-82 ◽

Cited By ~ 33

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.

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Pitch of Harmonic Complex Tones: Rate-Place Coding of Resolved Components in Harmonic and Inharmonic Complex Tones in Auditory Midbrain

10.1101/802827 ◽

2019 ◽

Author(s):

Yaqing Su ◽

Bertrand Delgutte

Keyword(s):

Primary Auditory Cortex ◽

Auditory Pathway ◽

Sound Level ◽

Auditory Midbrain ◽

Harmonic Complex ◽

Local Maxima ◽

Firing Rates ◽

Sound Levels ◽

Complex Tones ◽

Frequency Components

AbstractHarmonic complex tones (HCT) commonly occurring in speech and music evoke a strong pitch at their fundamental frequency (F0), especially when they contain harmonics individually resolved by the cochlea. When all frequency components of an HCT are shifted by the same amount, the pitch of the resulting inharmonic tone (IHCT) also shifts although the envelope repetition rate is unchanged. A rate-place code whereby resolved harmonics are represented by local maxima in firing rates along the tonotopic axis has been characterized in the auditory nerve and primary auditory cortex, but little is known about intermediate processing stages. We recorded single neuron responses to HCT and IHCT with varying F0 and sound level in the inferior colliculus (IC) of unanesthetized rabbits. Many neurons showed peaks in firing rates when a low-numbered harmonic aligned with the neuron’s characteristic frequency, demonstrating “rate-place” coding. The IC rate-place code was most prevalent for F0>800 Hz, was only moderately dependent on sound level over a 40 dB range, and was not sensitive to stimulus harmonicity. A spectral receptive-field model incorporating broadband inhibition better predicted the neural responses than a purely excitatory model, suggesting an enhancement of the rate-place representation by inhibition. Some IC neurons showed facilitation in response to HCT, similar to cortical “harmonic template neurons” (Feng and Wang 2017), but to a lesser degree. Our findings shed light on the transformation of rate-place coding of resolved harmonics along the auditory pathway, and suggest a gradual emergence of harmonic templates from low to high processing centers.Significance statementHarmonic complex tones are ubiquitous in speech and music and produce strong pitch percepts in human listeners when they contain frequency components that are individually resolved by the cochlea. Here, we characterize a “rate-place” code for resolved harmonics in the auditory midbrain that is more robust across sound levels than the peripheral rate-place code and insensitive to the harmonic relationships among frequency components. We use a computational model to show that inhibition may play an important role in shaping the rate-place code. We also show that midbrain auditory neurons can demonstrate similar properties as cortical harmonic template neurons. Our study fills a gap in understanding the transformation in neural representations of resolved harmonics along the auditory pathway.

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The Spatial Selective Auditory Attention of Cochlear Implant Users in Different Conversational Sound Levels

Journal of Clinical Medicine ◽

10.3390/jcm10143078 ◽

2021 ◽

Vol 10 (14) ◽

pp. 3078

Author(s):

Sara Akbarzadeh ◽

Sungmin Lee ◽

Chin-Tuan Tan

Keyword(s):

Cochlear Implant ◽

Sound Level ◽

Auditory Attention ◽

Impaired Hearing ◽

Speech Stimuli ◽

Electric Hearing ◽

Sound Levels ◽

Acoustic Hearing ◽

Speech Envelope ◽

Different Levels

In multi-speaker environments, cochlear implant (CI) users may attend to a target sound source in a different manner from normal hearing (NH) individuals during a conversation. This study attempted to investigate the effect of conversational sound levels on the mechanisms adopted by CI and NH listeners in selective auditory attention and how it affects their daily conversation. Nine CI users (five bilateral, three unilateral, and one bimodal) and eight NH listeners participated in this study. The behavioral speech recognition scores were collected using a matrix sentences test, and neural tracking to speech envelope was recorded using electroencephalography (EEG). Speech stimuli were presented at three different levels (75, 65, and 55 dB SPL) in the presence of two maskers from three spatially separated speakers. Different combinations of assisted/impaired hearing modes were evaluated for CI users, and the outcomes were analyzed in three categories: electric hearing only, acoustic hearing only, and electric + acoustic hearing. Our results showed that increasing the conversational sound level degraded the selective auditory attention in electrical hearing. On the other hand, increasing the sound level improved the selective auditory attention for the acoustic hearing group. In the NH listeners, however, increasing the sound level did not cause a significant change in the auditory attention. Our result implies that the effect of the sound level on selective auditory attention varies depending on the hearing modes, and the loudness control is necessary for the ease of attending to the conversation by CI users.

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Impact of sound levels and patient-related factors on sleep of patients in the intensive care unit: a cross-sectional cohort study

Scientific Reports ◽

10.1038/s41598-020-76314-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Piotr F. Czempik ◽

Agnieszka Jarosińska ◽

Krystyna Machlowska ◽

Michał P. Pluta

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Sleep Quality ◽

Sleep Duration ◽

Smartphone Application ◽

Sound Level ◽

Related Factors ◽

Cross Sectional ◽

Sound Levels ◽

The Impact

Abstract Sleep disruption is common in patients in the intensive care unit (ICU). The aim of the study was to measure sound levels during sleep-protected time in the ICU, determine sources of sound, assess the impact of sound levels and patient-related factors on duration and quality of patients' sleep. The study was performed between 2018 and 2019. A commercially available smartphone application was used to measure ambient sound levels. Sleep duration was measured using the Patient's Sleep Behaviour Observational Tool. Sleep quality was assessed using the Richards-Campbell Sleep Questionnaire (RCSQ). The study population comprised 18 (58%) men and 13 (42%) women. There were numerous sources of sound. The median duration of sleep was 5 (IQR 3.5–5.7) hours. The median score on the RCSQ was 49 (IQR 28–71) out of 100 points. Sound levels were negatively correlated with sleep duration. The cut-off peak sound level, above which sleep duration was shorter than mean sleep duration in the cohort, was 57.9 dB. Simple smartphone applications can be useful to estimate sound levels in the ICU. There are numerous sources of sound in the ICU. Individual units should identify and eliminate their own sources of sound. Sources of sound producing peak sound levels above 57.9 dB may lead to shorter sleep and should be eliminated from the ICU environment. The sound levels had no effect on sleep quality.

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Incubator Noise

PEDIATRICS ◽

10.1542/peds.56.4.617 ◽

1975 ◽

Vol 56 (4) ◽

pp. 617-617

Author(s):

Gōsta Blennow ◽

Nils W. Svenningsen ◽

Bengt Almquist

Keyword(s):

Low Frequency ◽

Sound Level ◽

Noise Levels ◽

Frequency Sound ◽

Mechanical Noise ◽

Sound Levels ◽

Infant Incubator ◽

Improved Model ◽

Model C

Recently we reported results from studies of incubator noise levels.1 It was found that in certain types of incubators the noise was considerable, and attention was called to the sound level in the construction of new incubators. Recently we had the opportunity to study an improved model of Isolette Infant Incubator Model C-86 where the mechanical noise from the electrically powered motor has been partially eliminated. With this modification it has been possible to lower the low-frequency sound levels to a certain degree in comparison to the levels registered in our study.

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Interaction between chemoreceptor and stretch receptor inputs at medullary respiratory neurons

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1994.266.6.r1951 ◽

1994 ◽

Vol 266 (6) ◽

pp. R1951-R1961 ◽

Cited By ~ 8

Author(s):

J. Bajic ◽

E. J. Zuperku ◽

M. Tonkovic-Capin ◽

F. A. Hopp

Keyword(s):

Time Course ◽

Afferent Input ◽

Respiratory Neurons ◽

Neuronal Responses ◽

Additive Interaction ◽

Dorsal Respiratory Group ◽

Afferent Inputs ◽

Discharge Patterns ◽

Carotid Body Chemoreceptors ◽

Common Carotid Arteries

The interaction between afferent inputs from carotid body chemoreceptors (CCRs) and from slowly adapting pulmonary stretch receptors (PSRs) on the discharge patterns of medullary inspiratory (I) and expiratory (E) neurons was characterized in thiopental sodium-anesthetized, paralyzed, ventilated dogs. A cycle-triggered ventilator was used to produce control and test pulmonary afferent input patterns. The CCRs were stimulated by phase-synchronized bolus injections of CO2-saturated saline into the common carotid arteries. Only those neurons whose discharge time course was altered by both inflation and CCR activation were studied. The dorsal respiratory group (DRG) I inflation-insensitive neurons were also included. Cycle-triggered histograms of unit activity were obtained for the neuronal responses to inflation, CO2 bolus, and their combination, as well as for the spontaneous control condition. Linearity of the interaction was tested by comparing the sum of the net individual responses to the net response of the combined afferent inputs. The results suggest that a linear (additive) interaction between CCR and PSR inputs exists for the DRG I inflation-sensitive neurons, the ventral respiratory group (VRG) I decrementing, and caudal VRG E augmenting neurons, while a nonadditive interaction exists for caudal VRG E decrementing bulbospinal neurons. The implications of these findings are discussed.

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

Journal of Neurophysiology ◽

10.1152/jn.00657.2016 ◽

2016 ◽

Vol 116 (6) ◽

pp. 2550-2563 ◽

Cited By ~ 2

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.

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The time course and relation of positive signal-averaged electrocardiograms by time-domain and spectral temporal mapping analyses after infarction

American Heart Journal ◽

10.1016/0002-8703(95)90004-7 ◽

1995 ◽

Vol 129 (2) ◽

pp. 238-251 ◽

Cited By ~ 4

Author(s):

Michael A. Graceffo ◽

Robert A. O'Rourke ◽

Charlotte Hibner ◽

Andrew J. Boulet

Keyword(s):

Time Domain ◽

Time Course ◽

Positive Signal

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Elevated Sound Levels within a Busy NICU

Neonatal Network The Journal of Neonatal Nursing ◽

10.1891/0730-0832.24.6.33 ◽

2005 ◽

Vol 24 (6) ◽

pp. 33-37 ◽

Cited By ~ 45

Author(s):

Charlene Krueger ◽

Susan Wall ◽

Leslie Parker ◽

Rose Nealis

Keyword(s):

Preterm Infants ◽

Noise Level ◽

Sound Level ◽

Behavioral Effects ◽

Outcome Variable ◽

Sound Levels ◽

Main Outcome Variable

Purpose: Elevated sound levels in the NICU may contribute to undesirable physiologic and behavioral effects in preterm infants. This study describes sound levels in a busy NICU in the southeastern U.S. and compares the findings with recommended NICU noise level standards.Design: NICU sound levels were recorded continuously at nine different locations within the NICU. Hourly measurements of loudness equivalent (Leq) sound level, sound level exceeded 10 percent of the time (L10), and maximum sound level (Lmax) were determined.Sample: Sound levels were sampled from nine different locations within the NICU.Main Outcome Variable: Sound levels are described using the hourly, A-weighted Leq, L10, and Lmax.Results: The overall average hourly Leq (M = 60.44 dB, range = 55–68 dB), L10 (M = 59.26 dB, range = 55–66 dB), and Lmax (M = 78.39, range = 69–93 dB) were often above the recommended sound levels (hourly Leq <50 dB, L10 <55 dB, and 1-second Lmax <70 dB). In addition, certain times of day, such as 6–7 AM and 10 AM–12 noon, were noisier than other times of day.

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