scholarly journals Midbrain Frequency Representation following Moderately Intense Neonatal Sound Exposure in a Precocious Animal Model (Chinchilla laniger)

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Lisa M. D’Alessandro ◽  
Robert V. Harrison
Keyword(s):  
Sensory Input ◽  
Single Neuron ◽  
Low Frequency ◽  
Central Nucleus ◽  
Auditory Midbrain ◽  
Early Postnatal Development ◽  
Sound Exposure ◽  
Cortical Level ◽  
Frequency Representation ◽  
Narrowband Sound

Auditory brain areas undergo reorganization resulting from abnormal sensory input during early postnatal development. This is evident from studies at the cortical level but it remains unclear whether there is reorganization in the auditory midbrain in a species similar to the human, that is, with early hearing onset. We have explored midbrain plasticity in the chinchilla, a precocious species that matches the human in terms of hearing development. Neonatal chinchillas were chronically exposed to a 2 kHz narrowband sound at 70 dB SPL for 4 weeks. Tonotopic maps in inferior colliculus (central nucleus) were defined based on single neuron characteristic frequency. We hypothesized an overrepresentation of the 2 kHz region of the maps. However, we observed a significant decrease in the proportion of neurons dedicated to the 2 kHz octave band and also away from the exposure frequency at 8 kHz. In addition, we report a significant increase in low frequency representation (<1 kHz), again a change to tonotopic mapping distant to the 2 kHz region. Thus in a precocious species, tonotopic maps in auditory midbrain are altered following abnormal stimulation during development. However, these changes are more complex than the overrepresentation of exposure related frequency regions that are often reported.

scholarly journals Changes to Neural Activation Patterns (c-fos Labeling) in Chinchilla Auditory Midbrain following Neonatal Exposure to an Enhanced Sound Environment

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Lisa M. D’Alessandro ◽  
Robert V. Harrison
Keyword(s):  
Brain Regions ◽  
Central Nucleus ◽  
Neural Activation ◽  
Auditory Midbrain ◽  
Sound Stimulation ◽  
Activation Patterns ◽  
Acoustic Environment ◽  
Sound Exposure ◽  
Sound Environment ◽  
Subcortical Regions

Sensory brain regions show neuroplastic changes following deficits or experimental augmentation of peripheral input during a neonatal period. We have previously shown reorganization of cortical tonotopic maps after neonatal cochlear lesions or exposure to an enhanced acoustic environment. Such experiments probe the cortex and show reorganization, but it is unclear if such changes are intrinsically cortical or reflect projections from modified subcortical regions. Here, we ask whether an enhanced neonatal acoustic environment can induce midbrain (inferior colliculus (IC)) changes. Neonatal chinchillas were chronically exposed to a 70 dB SPL narrowband (2 ± 0.25 kHz) sound stimulus for 4 weeks. In line with previous studies, we hypothesized that such exposure would induce widening of the 2 kHz tonotopic map region in IC. To probe c-fos expression in IC (central nucleus), sound-exposed and nonexposed animals were stimulated with a 2 kHz stimulus for 90 minutes. In sound-exposed subjects, we find no change in the width of the 2 kHz tonotopic region; thus, our hypothesis is not supported. However, we observed a significant increase in the number of c-fos-labeled neurons over a broad region of best frequencies. These data suggest that neonatal sound exposure can modify midbrain regions and thus change the way neurons in IC respond to sound stimulation.

scholarly journals Low-frequency oscillations in cortical level to help diagnose task-specific dystonia

2021 ◽  
pp. 105444
Author(s):  
Chun-Chuan Chen ◽  
Antonella Macerollo ◽  
Hoon-Ming Heng ◽  
Ming-Kuei Lu ◽  
Chon-Haw Tsai ◽  
...  
Keyword(s):  
Low Frequency ◽  
Cortical Level ◽  
Low Frequency Oscillations

Preparing for the unpredictable: adaptive feedback enhances the response to unexpected communication signals

2012 ◽  
Vol 107 (4) ◽  
pp. 1241-1246 ◽  
Author(s):  
Gary Marsat ◽  
Leonard Maler
Keyword(s):  
Nervous System ◽  
Sensory Input ◽  
Low Frequency ◽  
Excitatory Input ◽  
Negative Image ◽  
Communication Signals ◽  
First Order ◽  
Communication Signal ◽  
Apical Dendrites ◽  
Spike Bursts

To interact with the environment efficiently, the nervous system must generate expectations about redundant sensory signals and detect unexpected ones. Neural circuits can, for example, compare a prediction of the sensory signal that was generated by the nervous system with the incoming sensory input, to generate a response selective to novel stimuli. In the first-order electrosensory neurons of a gymnotiform electric fish, a negative image of low-frequency redundant communication signals is subtracted from the neural response via feedback, allowing unpredictable signals to be extracted. Here we show that the cancelling feedback not only suppresses the predictable signal but also actively enhances the response to the unpredictable communication signal. A transient mismatch between the predictive feedback and incoming sensory input causes both to be positive: the soma is suddenly depolarized by the unpredictable input, whereas the neuron's apical dendrites remain depolarized by the lagging cancelling feedback. The apical dendrites allow the backpropagation of somatic spikes. We show that backpropagation is enhanced when the dendrites are depolarized, causing the unpredictable excitatory input to evoke spike bursts. As a consequence, the feedback driven by a predictable low-frequency signal not only suppresses the response to a redundant stimulus but also induces a bursting response triggered by unpredictable communication signals.

Effects of interaural time delays of noise stimuli on low-frequency cells in the cat's inferior colliculus. II. Responses to band-pass filtered noises

1987 ◽  
Vol 58 (3) ◽  
pp. 543-561 ◽  
Author(s):  
J. C. Chan ◽  
T. C. Yin ◽  
A. D. Musicant
Keyword(s):  
Inferior Colliculus ◽  
Time Delays ◽  
Discharge Rate ◽  
Low Frequency ◽  
Central Peak ◽  
Broadband Noise ◽  
Central Nucleus ◽  
Rate Curve ◽  
Median Frequency ◽  
Band Pass

1. We studied cells in the central nucleus of the inferior colliculus of the cat that were sensitive to interaural time delays (ITDs) in order to evaluate the influence of the stimulus spectrum of noise signals. Stimuli were sharply filtered low-, high-, and band-pass noise signals whose cutoff frequencies and bandwidths were systematically varied. The responses to ITDs of these noise signals were compared with responses obtained to ITDs of broadband noise and pure tones. 2. The discharge rate in response to band-pass noise as a function of ITD was usually a cyclic function with decreasing peak amplitudes at longer ITDs. The reciprocal of the mean interval between adjacent peaks indicated how rapidly the response rate varied with ITD and was termed the response frequency (RF). This RF was approximately equal to the median frequency of the stimulus spectrum filtered by the cell's sync-rate curve, which was the product of the synchronization to interaural phase and the discharge rate plotted against frequency. This suggests that the RF was determined by all the spectral components in the stimulus that fell within the frequency range in which the cell's response was synchronized. The contribution of each component was proportional to the sync-rate for that frequency. 3. The central peak of the ITD function usually fell within the physiological range of ITDs (+/- 400 microseconds). The location of this peak did not vary significantly with changes in stimulus spectrum by comparison with responses to tones of different frequency. Its shape also remained constant, except for a decrease in width when high-frequency components within the range of the sync-rate curve were added to the stimulus. A few cells responded with a minimal discharge instead of a maximal near-zero ITD, and this central minimum had similar properties as the central peak. The amplitude of the secondary peaks of the ITD function decreased as the stimulus bandwidth that overlapped the sync-rate curve broadened. 4. The sum of the ITD functions to two band-pass signals was similar to that of a broadband signal whose spectrum was composed of the sum of the band-pass spectra. 5. From these binaural responses we could make inferences about the response characteristics of the monaural inputs to binaural neurons. We then verified these predictions by studying responses of low-frequency trapezoid body fibers to band-pass noises.

scholarly journals The representations of adolescents about gynecological consultation

2014 ◽  
Vol 48 (3) ◽  
pp. 438-445 ◽  
Author(s):  
Vera Lúcia de Oliveira Gomes ◽  
Adriana Dora da Fonseca ◽  
Denize Cristina de Oliveira ◽  
Camila Daiane Silva ◽  
Daniele Ferreira Acosta ◽  
...  
Keyword(s):  
Sexual And Reproductive Health ◽  
Social Representations ◽  
Low Frequency ◽  
Social Representation ◽  
Contextual Analysis ◽  
Central Nucleus ◽  
Treatment Results ◽  
Education Professionals ◽  
The Social ◽  
Qualitative Descriptive

Objective: To analyze the social representation of adolescents about gynecological consultation and the influence of those in searching for consultations. Method: Qualitative descriptive study based on the Social Representations Theory, conducted with 50 adolescents in their last year of middle school. The data was collected between April and May of 2010 by Evocations and a Focal Group. The software EVOC and contextual analysis were used in the data treatment. Results: The elements fear and constraint, constant in the central nucleus, can justify the low frequency of adolescents in consultations. The term embarrassment in the peripheral system reinforce current sociocultural norms, while prevention, associated with learning about sex and clarifying doubts, allows to envision an educative function. Obtained testimonies in the focal groups exemplify and reinforce those findings. Conclusion: For an effective health education, professionals, including nurses, need to clarify the youth individually and collectively about their rights to privacy, secrecy, in addition to focus the gynecological consultation as a promotion measure to sexual and reproductive health.

Effect of Infrasound and Low Frequency Sound Exposure at Intensities below 100 dB(SPL) on the Rota-Rod Treadmill Performance of Guinea Pigs

1983 ◽  
Vol 2 (3) ◽  
pp. 37-41 ◽  
Author(s):  
Naoki Maehara ◽  
Reiko Kishi ◽  
Terukazu Sadamoto ◽  
Izumi Harabuchi ◽  
Kohtaroh Yamamura
Keyword(s):  
Guinea Pigs ◽  
Motor Coordination ◽  
Low Frequency ◽  
Vestibular Function ◽  
Moderate Intensity ◽  
Endurance Time ◽  
Frequency Sound ◽  
Sound Exposure ◽  
Preliminary Study

A preliminary study to investigate whether or not long-term exposure to very low frequency sound at a moderate intensity below 100 dB(SPL) affects the vestibular function and/or motor coordination in guinea pigs was carried out. At first, optimal conditions of Rota-Rod Treadmill performance for guinea pigs were determined. Then, 20 and 40 Hz-low frequency sound at 80–90 dB(SPL) exposure was used for 150 minutes and measurement of the endurance time on the Rota-Rod Treadmill was carried out at rotation speeds of 8 rpm or 10 rpm. At 10 rpm rotation speed, and 20 Hz, 90 dB(SPL) stimulus, the endurance time was significantly reduced at 150 minutes, compared with that of the control, whereas no significant reduction in endurance time was obtained at 85 dB(SPL).

Central and peripheral contributions to coding of acoustic space by neurons in inferior colliculus of cat

1986 ◽  
Vol 55 (3) ◽  
pp. 587-603 ◽  
Author(s):  
M. B. Calford ◽  
D. R. Moore ◽  
M. E. Hutchings
Keyword(s):  
Inferior Colliculus ◽  
Single Unit ◽  
Arrival Time ◽  
Interaural Time Difference ◽  
Free Field ◽  
Low Frequency ◽  
Intensity Function ◽  
Central Nucleus ◽  
Stimulus Position ◽  
Acoustic Space

Recordings of response to free-field stimuli at best frequency were made from single units in the central nucleus of the inferior colliculus of anesthetized cats. Stimulus position was varied in azimuth, and the responses of units were compared with variation in the intensity and arrival time of the sound at each ear, derived from cochlear microphonic (CM) recordings. CM recordings were made at each frequency and at every point in space for which single-unit data were collected. Interaural time difference (delay) increased monotonically, but not linearly, as the stimulus was moved away from the midline. However, a given delay did not represent a single azimuth across frequency. Low-frequency interaural intensity differences (IIDs) were monotonic across azimuth and peaked at, or near, the poles. Higher-frequency IIDs were nonmonotonic and peaked relatively close to the midline, decreasing toward the poles. Units that showed little variation in discharge across azimuth formed 28% of the sample and were classified as omnidirectional. For other units, the spike-count intensity function and the variation of the CM with azimuth were combined to form a derived monaural azimuth function. For 29% of those units showing azimuthal sensitivity, the derived monaural azimuth function matched the actual azimuth function. This suggested that these units received input from only one ear. The largest group of azimuthally sensitive units (47%) was formed from those units inferred to be IID sensitive. At higher frequencies these units displayed a peaked azimuth function paralleling the nonmonotonic relation of IID to azimuth. The proportion of inferred IID-sensitive units was close to that found in dichotic studies.

Applied Research on Segmented-Hilbert-Huang Transform Algorithm in Fault Feature Extraction of Main Reducer

2013 ◽  
Vol 823 ◽  
pp. 417-421 ◽  
Author(s):  
Feng Yun Huang ◽  
Huan Huan Sun ◽  
Hao Pan ◽  
Wei Ru Zhang
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Vibration Signal ◽  
Model Decomposition ◽  
Frequency Dictionary ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
Frequency Representation ◽  
Scale Characteristics ◽  
Frequency Impulse

For the multi-time scale characteristics of vibration signal, a composite multi-frequency dictionary combining the low-frequency Fourier dictionary and the high-frequency impulse time-frequency dictionary is constituted, to decompose multi-component vibration signal into the combination of several one-component signals. The use of empirical model decomposition (EDM) in high-frequency impulse Component signal including feature information is to realize segmented Hilbert-Huang transform of signal and to acquire the time-frequency representation of every one-component signal, which is the process of fault information extraction of vibration signal. The application of the method in main reducer fault diagnosis verifies the engineering practicability and validity of the new algorithm.

scholarly journals Inverse Density of Iba1 and Glutamine Synthetase Expressing Glia in Rat Inferior Colliculus

2021 ◽  
Author(s):  
Llwyd David Orton
Keyword(s):  
Glial Cell ◽  
Calcium Binding ◽  
Cell Types ◽  
Central Nucleus ◽  
Gradual Transition ◽  
Relative Distribution ◽  
Dorsal Cortex ◽  
Auditory Midbrain ◽  
Cellular Density ◽  
Male Wistar Rats

Microglia and astrocytes undertake numerous essential roles in nervous systems but we know little of their anatomical distribution within numerous nuclei. In the principal nuclei of the mammalian auditory midbrain, the inferior colliculi (IC), the cellular density and relative distribution of glutamate synthetase (GS) expressing astrocytes and ionized calcium-binding adapter molecule 1 (Iba1) expressing microglia is unknown. To address this, the IC of young adult, male Wistar rats were immunohistochemically labelled for GS and Iba1, using chromogenic methods. Sub-regions of imaged IC sections were demarked and soma density of both cell types determined. GS labelled somata were twice more densely packed as Iba1 labelled somata throughout IC parenchyma and peri-vascular regions. Furthermore, GS labelled somata density was significantly lower in dorsal cortex than external cortex or central nucleus. Iba1 labelled somata density exhibited the opposite trend, revealing an inverse density of these glial cell types between IC sub-regions. GS labelled neuropil was strongest in the cortices with and a gradual transition of lighter labelling towards central nucleus. These data provide the first detailed descriptions of GS labelling in IC and demonstrate sub-regional differences in IC glial cell density. Taken together, these findings suggest neurochemical specialization of glia in IC sub-regions, likely related to local physiological and metabolic demands, with implications for IC function.

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