scholarly journals Responses of Inferior Colliculus Neurons to Double Harmonic Tones

2007 ◽  
Vol 98 (6) ◽  
pp. 3171-3184 ◽  
Author(s):  
Donal G. Sinex ◽  
Hongzhe Li
Keyword(s):  
Inferior Colliculus ◽  
Auditory System ◽  
Temporal Pattern ◽  
Second Harmonic ◽  
Neural Mechanisms ◽  
Acoustic Properties ◽  
Discharge Pattern ◽  
The Difference ◽  
Discharge Patterns ◽  
Simultaneous Sounds

The auditory system can segregate sounds that overlap in time and frequency, if the sounds differ in acoustic properties such as fundamental frequency (f0). However, the neural mechanisms that underlie this ability are poorly understood. Responses of neurons in the inferior colliculus (IC) of the anesthetized chinchilla were measured. The stimuli were harmonic tones, presented alone (single harmonic tones) and in the presence of a second harmonic tone with a different f0 (double harmonic tones). Responses to single harmonic tones exhibited no stimulus-related temporal pattern, or in some cases, a simple envelope modulated at f0. Responses to double harmonic tones exhibited complex slowly modulated discharge patterns. The discharge pattern varied with the difference in f0 and with characteristic frequency. The discharge pattern also varied with the relative levels of the two tones; complex temporal patterns were observed when levels were equal, but as the level difference increased, the discharge pattern reverted to that associated with single harmonic tones. The results indicated that IC neurons convey information about simultaneous sounds in their temporal discharge patterns and that the patterns are produced by interactions between adjacent components in the spectrum. The representation is “low-resolution,” in that it does not convey information about single resolved components from either individual sound.

scholarly journals Prevalence of Stereotypical Responses to Mistuned Complex Tones in the Inferior Colliculus

2005 ◽  
Vol 94 (5) ◽  
pp. 3523-3537 ◽  
Author(s):  
Donal G. Sinex ◽  
Hongzhe Li ◽  
David S. Velenovsky
Keyword(s):  
Inferior Colliculus ◽  
Major Effect ◽  
Stimulus Level ◽  
Neural Mechanisms ◽  
Discharge Pattern ◽  
Harmonic Complex ◽  
Long Latency ◽  
Complex Tones ◽  
Discharge Patterns ◽  
Response Envelope

The human auditory system has an exceptional ability to separate competing sounds, but the neural mechanisms that underlie this ability are not understood. Responses of inferior colliculus (IC) neurons to “mistuned” complex tones were measured to investigate possible neural mechanisms for spectral segregation. A mistuned tone is a harmonic complex tone in which the frequency of one component has been changed; that component may be heard as a separate sound source, suggesting that the mistuned tone engages the same mechanisms that contribute to the segregation of natural sounds. In this study, the harmonic tone consisted of eight harmonics of 250 Hz; in the mistuned tone, the frequency of the fourth harmonic was increased by 12% (120 Hz). The mistuned tone elicited a stereotypical discharge pattern, consisting of peaks separated by about 8 ms and a response envelope modulated with a period of 100 ms, which bore little resemblance to the discharge pattern elicited by the harmonic tone or to the stimulus waveform. Similar discharge patterns were elicited from many neurons with a range of characteristic frequencies, especially from neurons that exhibited short-latency sustained responses to pure tones. In contrast, transient and long-latency neurons usually did not exhibit the stereotypical discharge pattern. The discharge pattern was generally stable when the stimulus level or component phase was varied; the major effect of these manipulations was to shift the phase of the response envelope. Simulation of IC responses with a computational model suggested that off-frequency inhibition could produce discharge patterns with these characteristics.

Effects of Amplitude Modulation on the Coding of Interaural Time Differences of Low-Frequency Sounds in the Inferior Colliculus. II. Neural Mechanisms

2003 ◽  
Vol 90 (5) ◽  
pp. 2827-2836 ◽  
Author(s):  
W. R. D'Angelo ◽  
S. J. Sterbing ◽  
E.-M. Ostapoff ◽  
S. Kuwada
Keyword(s):  
Inferior Colliculus ◽  
Background Noise ◽  
Modulation Depth ◽  
Interaural Time Difference ◽  
Low Frequency ◽  
Companion Paper ◽  
Neural Mechanisms ◽  
Physical Factors ◽  
Correlation Spectrum ◽  
The Difference

In our companion paper, we reported on interaural time difference (ITD)-sensitive neurons that enhanced, suppressed, or did not change their response when identical AM was added to both ears. Here, we first examined physical factors such as the difference in the interaural correlation, spectrum, or energy between the modulated and unmodulated signals. These were insufficient to explain the observed enhancement and suppression. We then examined neural mechanisms by selectively modulating the signal to each ear, varying modulation depth, and adding background noise to the unmodulated signal. These experiments implicated excitatory and inhibitory monaural inputs to the inferior colliculus (IC). These monaural inputs are postulated to adapt to an unmodulated signal and adapt less to a modulated signal. Thus enhancement or suppression is created by the convergence of these excitatory or inhibitory inputs with the inputs from the binaural comparators. Under modulation, the role of the monaural input is to shift the threshold of the IC neuron. Consistent with this role, background noise mimicked the effect of modulation. Functionally, enhancement and suppression may serve in detecting the degree of modulation in a sound source while preserving ITD information.

Two discharge patterns of carotid body chemoreceptors in the goat

1990 ◽  
Vol 69 (2) ◽  
pp. 734-739 ◽  
Author(s):  
W. Z. Niu ◽  
M. J. Engwall ◽  
G. E. Bisgard
Keyword(s):  
Carotid Body ◽  
Interspike Interval ◽  
Spike Trains ◽  
Discharge Pattern ◽  
The Difference ◽  
Discharge Patterns ◽  
Carotid Body Chemoreceptors ◽  
Arterial Po2 ◽  
Interval Distribution ◽  
Prominent Peak

Twenty-nine single carotid body chemoreceptor units recorded during normocapnic normoxia from 20 anesthetized goats were classified into two groups by discharge pattern. Thirteen fibers, which had interspike interval distributions with a prominent peak [24.0 +/- 9.8% (SD)] at 0- to 20-ms bin, were termed bursting fibers (BF). The 16 remaining fibers were termed nonbursting fibers (NBF); these had no notable peak in the interval distributions. During hypoxia and hypercapnia, the chemoreceptor fibers continued to discharge in their established patterns. The interval distribution of most NBF spike trains could be described with the Poisson process, but none of the BF could be. However, except for the intervals in the range of 0-20 ms, the interval distribution of the BF could be described as exponential. This study suggests that 1) there are two distinct populations of the goat chemoreceptor fiber, each with an inherent discharge pattern; 2) the chemoreceptor did not code information about arterial PO2 and PCO2 in different patterns; and 3) the basic chemotransduction mechanism is likely the same in BF and NBF, and the difference in discharge pattern is more likely to reflect processes downstream from the transducer.

Neuromodulatory Feedback to the Inferior Colliculus

2018 ◽  
pp. 576-610 ◽  
Author(s):  
Laura Hurley
Keyword(s):  
Inferior Colliculus ◽  
Auditory System ◽  
Auditory Processing ◽  
Internal State ◽  
Brain Regions ◽  
Auditory Information ◽  
Situational Variables ◽  
Acoustic Stimuli ◽  
Functionally Diverse ◽  
Behavioral Information

The inferior colliculus (IC) receives prominent projections from centralized neuromodulatory systems. These systems include extra-auditory clusters of cholinergic, dopaminergic, noradrenergic, and serotonergic neurons. Although these modulatory sites are not explicitly part of the auditory system, they receive projections from primary auditory regions and are responsive to acoustic stimuli. This bidirectional influence suggests the existence of auditory-modulatory feedback loops. A characteristic of neuromodulatory centers is that they integrate inputs from anatomically widespread and functionally diverse sets of brain regions. This connectivity gives neuromodulatory systems the potential to import information into the auditory system on situational variables that accompany acoustic stimuli, such as context, internal state, or experience. Once released, neuromodulators functionally reconfigure auditory circuitry through a variety of receptors expressed by auditory neurons. In addition to shaping ascending auditory information, neuromodulation within the IC influences behaviors that arise subcortically, such as prepulse inhibition of the startle response. Neuromodulatory systems therefore provide a route for integrative behavioral information to access auditory processing from its earliest levels.

scholarly journals Acoustic Characterization of Some Steel Industry Waste Materials

2021 ◽  
Vol 11 (13) ◽  
pp. 5924
Author(s):  
Elisa Levi ◽  
Simona Sgarbi ◽  
Edoardo Alessio Piana
Keyword(s):  
Thermal Characteristic ◽  
Environmental Benefits ◽  
Acoustic Properties ◽  
Physical Parameters ◽  
Industry Waste ◽  
Acoustic Characterization ◽  
Minimization Procedure ◽  
The Difference ◽  
By Products

From a circular economy perspective, the acoustic characterization of steelwork by-products is a topic worth investigating, especially because little or no literature can be found on this subject. The possibility to reuse and add value to a large amount of this kind of waste material can lead to significant economic and environmental benefits. Once properly analyzed and optimized, these by-products can become a valuable alternative to conventional materials for noise control applications. The main acoustic properties of these materials can be investigated by means of a four-microphone impedance tube. Through an inverse technique, it is then possible to derive some non-acoustic properties of interest, useful to physically characterize the structure of the materials. The inverse method adopted in this paper is founded on the Johnson–Champoux–Allard model and uses a standard minimization procedure based on the difference between the sound absorption coefficients obtained experimentally and predicted by the Johnson–Champoux–Allard model. The results obtained are consistent with other literature data for similar materials. The knowledge of the physical parameters retrieved applying this technique (porosity, airflow resistivity, tortuosity, viscous and thermal characteristic length) is fundamental for the acoustic optimization of the porous materials in the case of future applications.

scholarly journals ANALYSIS OF ACOUSTIC ANISOTROPY PARAMETERS OF PYROXENE-MAGNETITE ROCKS OF THE PISCHANKA STRUCTURE

2020 ◽  
pp. 40-45
Author(s):  
I. Bezrodna ◽  
V. Svystov ◽  
D. Bezrodny
Keyword(s):  
Acoustic Properties ◽  
Significant Heterogeneity ◽  
Depth Range ◽  
Transverse Waves ◽  
Acoustic Anisotropy ◽  
Micro Cracks ◽  
Acoustic Tensor ◽  
Transverse Isotropic ◽  
Different Depths ◽  
The Difference

The analysis of the results of acoustic properties of rocks study of Pischans`ka iron-ore structure is presented. The aim of the work is to establish the features of the distribution of acoustic properties and parameters of acoustic anisotropy in samples of core rocks selected from the well No. 3 of the Pischans`ka structure to determine the nature of its occurrence. A sample of 35 samples from the depth range 144-273 m is divided into 3 groups of rocks, namely: magnetite-pyroxene, quartz-magnetitepyroxene and biotite-amphibole crystalline shales. Based on an invariant polarization method, a number of acoustic laboratory measurements have been carried out. The values of the measured phase velocities "quasi-longitudinal" and two "quasi-transverse" waves at the stage of measurements showed significant acoustic anisotropy of the rocks. The ranges of the measured speeds of the collection samples are 7661 ÷ 5046 m / s for longitudinal waves and 4232 ÷ 2648 m/s for transverse ones. The difference in values measured for each of the sides of the cubic rhombic dodecahedron is from 100 to 800 m / s and from 0 to 500 m/s for Vp and Vs, respectively. The parameters of an acoustic ellipsoid were calculated, on the basis of which the division of samples into 3 main groups has been performed, according to the acoustic texture: acoustically linear, shale and rhombic. Separately, a group of samples with a more complex texture was discovered. The analysis of coefficients of anisotropy by different methods is carried out: longitudinal, transverse and relative acoustic anisotropy. Most of the samples are characterized by low or average acoustic anisotropy (from 2 to 7 %). A group of highly anisotropic rocks (11–14 %), represented by samples of biotite-amphibole crystalline silicates, is singled out. According to the parameters of the acoustic tensor of most samples, the transverse isotropic type of symmetry inherent to samples from the depth intervals 174–220 m and 222–232 m, while the smaller part is rhombic, is inherent. Differences in the parameters of anisotropy of samples can be explained by the significant heterogeneity of their textures, namely: micro cracks, minerals of various sizes, shapes and orientations. The results of the research show that the acoustic properties of the samples are quite heterogeneously distributed along the investigated depth range. This indicates the difficult conditions for the formation of rocks at different depths and the presence of different types of deformations, which accompanied the formation of the Pischans`ka structure.

Directional Hearing in the Japanese Quail (Coturnix Coturnix Japonica): I. Acoustic Properties of the Auditory System

1980 ◽  
Vol 86 (1) ◽  
pp. 135-151
Author(s):  
K. G. HILL ◽  
D. B. LEWIS ◽  
M. E. HUTCHINGS ◽  
R. B. COLES
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
External Surface ◽  
Acoustic Properties ◽  
Coturnix Japonica ◽  
Directional Hearing ◽  
Coturnix Coturnix Japonica ◽  
Coturnix Coturnix ◽  
External Pressures ◽  
Air Space

The auditory tympana in the quail, Coturnix coturnix japonica (L.) are internally coupled by an interaural air space. Unilaterally applied sound causing vibration of the ipsilateral tympanum is conducted through the interauralcavity to the inside surface of the contralateral tympanum. In a free soundfield at frequencies up to 3150 Hz, sound pressure at the external surface of the tympanum contralateral to the source is within about 3 dB of the pressure exterior to the ipsilateral tympanum. Sound pressures developed at the inner surfaces of the tympana are of similar amplitude to the external pressures at several frequencies in the range 800–6300 Hz. In addition, pressure ateach side of the tympanum ipsilateral to the source are generally out of phase, whereas pressures at each side of the contralateral tympanum are relatively close to the same phase. From measurements of amplitude and phase of the interacting pressures at the tympanum, the calculated driving pressure at the ipsilateral tympanum exceeds that at the contralateral tympanum by 10–20 dB over a range of frequencies. The auditory tympana in quail have considerable inherent directionality, therefore, due to their function aspressure-gradient receivers. Anatomical analogies with anurans and reptiles indicate that they derive directional hearing from the same acoustic mechanism that operates in the quail.

Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. I. Receptive Fields and Discharge Patterns

1999 ◽  
Vol 81 (2) ◽  
pp. 825-834 ◽  
Author(s):  
Iran Salimi ◽  
Thomas Brochier ◽  
Allan M. Smith
Keyword(s):  
Receptive Field ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Single Cells ◽  
Precision Grip ◽  
Receptive Fields ◽  
Pressure Change ◽  
Discharge Pattern ◽  
Cortical Cells ◽  
Discharge Patterns

Neuronal activity in somatosensory cortex of monkeys using a precision grip. I. Receptive fields and discharge patterns. Three adolescent Macaca fascicularis monkeys weighing between 3.5 and 4 kg were trained to use a precision grip to grasp a metal tab mounted on a low friction vertical track and to lift and hold it in a 12- to 25-mm position window for 1 s. The surface texture of the metal tab in contact with the fingers and the weight of the object could be varied. The activity of 386 single cells with cutaneous receptive fields contacting the metal tab were recorded in Brodmann’s areas 3b, 1, 2, 5, and 7 of the somatosensory cortex. In this first of a series of papers, we describe three types of discharge pattern, the receptive-field properties, and the anatomic distribution of the neurons. The majority of the receptive fields were cutaneous and covered less than one digit, and a χ2 test did not reveal any significant differences in the Brodmann’s areas representing the thumb and index finger. Two broad categories of discharge pattern cells were identified. The first category, dynamic cells, showed a brief increase in activity beginning near grip onset, which quickly subsided despite continued pressure applied to the receptive field. Some of the dynamic neurons responded to both skin indentation and release. The second category, static cells, had higher activity during the stationary holding phase of the task. These static neurons demonstrated varying degrees of sensitivity to rates of pressure change on the skin. The percentage of dynamic versus static cells was about equal for areas 3b, 2, 5, and 7. Only area 1 had a higher proportion of dynamic cells (76%). A third category was identified that contained cells with significant pregrip activity and included cortical cells with both dynamic or static discharge patterns. Cells in this category showed activity increases before movement in the absence of receptive-field stimulation, suggesting that, in addition to peripheral cutaneous input, these cells also receive strong excitation from movement-related regions of the brain.

Temporal coding of envelopes and their interaural delays in the inferior colliculus of the unanesthetized rabbit

1989 ◽  
Vol 61 (2) ◽  
pp. 257-268 ◽  
Author(s):  
R. Batra ◽  
S. Kuwada ◽  
T. R. Stanford
Keyword(s):  
Inferior Colliculus ◽  
Phase Locking ◽  
Acoustic Stimulus ◽  
Low Frequency ◽  
Auditory Pathway ◽  
Temporal Coding ◽  
Time Of Arrival ◽  
Unanesthetized Rabbit ◽  
The Difference ◽  
Ipsilateral Stimulation

1. The difference in the time of arrival of a sound at the two ears can be used to locate its source along the azimuth. Traditionally, it has been thought that only the on-going interaural temporal disparities (ITDs) produced by sounds of lower frequency (approximately less than 2 kHz) could be used for this purpose. However, ongoing ITDs of low frequency are also produced by envelopes of amplitude-modulated (AM) tones. These ITDs can be detected and used to lateralize complex high-frequency sounds (1, 8, 12, 15, 22, 24, 26). Auditory neurons synchronize to the modulation envelope, but do so at progressively lower modulation frequencies at higher levels of the auditory pathway. Some neurons of the cochlear nucleus synchronize best to frequencies as high as 700 Hz, but those of the inferior colliculus (IC) exhibit their best synchrony below 200 Hz. Even though synchrony to higher modulation frequencies is reduced at higher levels of the auditory pathway, is information about ITDs retained? 2. We answered this question by extracellularly recording the responses of neurons in the IC of the unanesthetized rabbit. We used an unanesthetized preparation because anesthesia alters the responses of neurons in the IC to both monaurally presented tones and ITDs. The unanesthetized rabbit is ideal for auditory research. Recordings can be maintained for long periods, and the acoustic stimulus to each ear can be independently controlled. 3. We studied the responses of 89 units to sinusoidally AM tones presented to the contralateral ear. For each unit, we recorded the response at several modulation frequencies. The degree of phase locking to the envelope at each frequency was measured using the synchronization coefficient. Two measures were used to assess the range of modulation frequencies over which phase locking occurred. The "best AM frequency" was the frequency at which we observed the greatest phase locking. The "highest AM frequency" was the highest frequency at which significant phase locking (0.001 level) was observed. We could not assess synchrony to ipsilateral AM tones directly, because most units did not respond to ipsilateral stimulation. 4. We studied the sensitivity of 63 units to ITDs produced by the envelopes of AM tones. Sensitivity to ITDs was tested by presenting AM tones to the two ears that had the same carrier frequency, but modulation frequencies that differed by 1 Hz. Units that were sensitive to ITDs responded to this stimulus by varying their response rate cyclically at the difference frequency, i.e., 1 Hz.(ABSTRACT TRUNCATED AT 400 WORDS)

Control of discharge patterns of medullary respiratory neurons by pulmonary vagal afferent inputs

1987 ◽  
Vol 253 (6) ◽  
pp. R809-R820 ◽  
Author(s):  
E. J. Zuperku ◽  
F. A. Hopp
Keyword(s):  
Linear Functions ◽  
Step Response ◽  
Respiratory Neurons ◽  
Step Frequency ◽  
Test Input ◽  
Linear Relationships ◽  
Vagal Afferent ◽  
The Difference ◽  
Time Courses ◽  
Discharge Patterns

To provide a better understanding of the central mechanisms by which pulmonary afferents reflexly control breathing, the responses of single respiratory neurons to vagal afferent patterns were analyzed. Respiratory-related unit (RRU) recordings were obtained from inspiratory (I), expiratory (E), and phase-spanning neurons in the ventral medulla of halothane-anesthetized, paralyzed, ventilated, vagotomized, mongrel dogs. Electrical stimulation of the largest vagal fibers was used to reflexly alter I and E durations (TI and TE) and to present various temporal input patterns to RRU. The net response was quantified by taking the difference between cycle-triggered histograms (CTH) of activity obtained during an input and the spontaneous control (no input) CTH. For step frequency patterns confined to either the I or E phase, 127 responses in 41 neurons were analyzed. The average step response time was greater than 500 ms. In general the time courses of the control and test-input discharge patterns were linearly related to one another. For I neurons the slopes (beta) of these relationships were linear functions of the vagal step frequency (Fv). Linear relationships were also obtained for 1/TI vs. Fv and 1/beta vs. TI. These results suggest that the vagal control of the discharge patterns of these neurons and phase timing is mediated via a process similar to gain modulation.

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