Effect of unilateral noise exposure on the tonotopic distribution of spontaneous activity in the cochlear nucleus and inferior colliculus in the cortically intact and decorticate rat

2005 ◽  
Vol 490 (4) ◽  
pp. 391-413 ◽  
Author(s):  
Thomas J. Imig ◽  
Dianne Durham
Keyword(s):  
Spontaneous Activity ◽  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Noise Exposure

scholarly journals Acute and Long-Term Effects of Noise Exposure on the Neuronal Spontaneous Activity in Cochlear Nucleus and Inferior Colliculus Brain Slices

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Moritz Gröschel ◽  
Jana Ryll ◽  
Romy Götze ◽  
Arne Ernst ◽  
Dietmar Basta
Keyword(s):  
Hearing Loss ◽  
Spontaneous Activity ◽  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Noise Exposure ◽  
Brain Slices ◽  
Noise Induced Hearing Loss ◽  
Long Term Effects ◽  
Noise Trauma

Noise exposure leads to an immediate hearing loss and is followed by a long-lasting permanent threshold shift, accompanied by changes of cellular properties within the central auditory pathway. Electrophysiological recordings have demonstrated an upregulation of spontaneous neuronal activity. It is still discussed if the observed effects are related to changes of peripheral input or evoked within the central auditory system. The present study should describe the intrinsic temporal patterns of single-unit activity upon noise-induced hearing loss of the dorsal and ventral cochlear nucleus (DCN and VCN) and the inferior colliculus (IC) in adult mouse brain slices. Recordings showed a slight, but significant, elevation in spontaneous firing rates in DCN and VCN immediately after noise trauma, whereas no differences were found in IC. One week postexposure, neuronal responses remained unchanged compared to controls. At 14 days after noise trauma, intrinsic long-term hyperactivity in brain slices of the DCN and the IC was detected for the first time. Therefore, increase in spontaneous activity seems to develop within the period of two weeks, but not before day 7. The results give insight into the complex temporal neurophysiological alterations after noise trauma, leading to a better understanding of central mechanisms in noise-induced hearing loss.

scholarly journals Noise-induced hyperactivity in the inferior colliculus: its relationship with hyperactivity in the dorsal cochlear nucleus

2012 ◽  
Vol 108 (4) ◽  
pp. 976-988 ◽  
Author(s):  
N. F. Manzoor ◽  
F. G. Licari ◽  
M. Klapchar ◽  
R. L. Elkin ◽  
Y. Gao ◽  
...  
Keyword(s):  
Spontaneous Activity ◽  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Time Course ◽  
Noise Exposure ◽  
Dorsal Cochlear Nucleus ◽  
Control Group ◽  
Before And After ◽  
Intense Noise ◽  
And Control

Intense noise exposure causes hyperactivity to develop in the mammalian dorsal cochlear nucleus (DCN) and inferior colliculus (IC). It has not yet been established whether the IC hyperactivity is driven by hyperactivity from extrinsic sources that include the DCN or instead is maintained independently of this input. We have investigated the extent to which IC hyperactivity is dependent on input from the contralateral DCN by comparing recordings of spontaneous activity in the IC of noise-exposed and control hamsters before and after ablation of the contralateral DCN. One group of animals was binaurally exposed to intense sound (10 kHz, 115 dB SPL, 4 h), whereas the control group was not. Both groups were studied electrophysiologically 2–3 wk later by first mapping spontaneous activity along the tonotopic axis of the IC to confirm induction of hyperactivity. Spontaneous activity was then recorded at a hyperactive IC locus over two 30-min periods, one with DCNs intact and the other after ablation of the contralateral DCN. In a subset of animals, activity was again mapped along the tonotopic axis after the time course of the activity was recorded before and after DCN ablation. Following recordings, the brains were fixed, and histological evaluations were performed to assess the extent of DCN ablation. Ablation of the DCN resulted in major reductions of IC hyperactivity. Levels of postablation activity in exposed animals were similar to the levels of activity in the IC of control animals, indicating an almost complete loss of hyperactivity in exposed animals. The results suggest that hyperactivity in the IC is dependent on support from extrinsic sources that include and may even begin with the DCN. This finding does not rule out longer term compensatory or homeostatic adjustments that might restore hyperactivity in the IC over time.

scholarly journals Apoptosis in the cochlear nucleus and inferior colliculus upon repeated noise exposure

2018 ◽  
Vol 20 (97) ◽  
pp. 223
Author(s):  
Felix Fröhlich ◽  
Moritz Gröschel ◽  
Ira Strübing ◽  
Arne Ernst ◽  
Dietmar Basta
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Noise Exposure

Responses of single units in cerebellar vermis of the cat to monaural and binaural stimuli

1975 ◽  
Vol 38 (2) ◽  
pp. 418-429 ◽  
Author(s):  
L. M. Aitkin ◽  
J. Boyd
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Single Units ◽  
Intensity Difference ◽  
Cerebellar Neurons ◽  
Monaural Stimulation ◽  
Sustained Responses ◽  
Maximal Discharge ◽  
Onset Responses ◽  
Stimulation Of

The responses of 146 cerebellar neurons to tone stimuli were studied in 29 cats anesthetized with chloralose-urethan and in 7 decerebrate preparations. Units were classified as onset or sustained firing. Onset spikes occurred on stimulation of either ear and showed binaural facilitation, while sustained discharges were frequently only excited by monaural stimulation. The latent periods of sustained discharges appeared to be shorter than those of onset responses, and sustained discharges were also more sharply tuned than the onset units. Evidence was presented suggesting that onset responses reflected input from the inferior colliculus and sustained responses, the cochlear nucleus. The sterotyped facilitatory behavior of onset units suggested that a maximal discharge might occur if sounds were of equal intensity at each ear; 26 neurons were examined with variable interaural time or intensity differences and 10 of these exhibited maximal firing when the interaural time and intensity difference was zero--i.e., if the sound was located directly in front of the head.

scholarly journals Synaptic Reorganization Response in the Cochlear Nucleus Following Intense Noise Exposure

Neuroscience ◽  
2019 ◽  
Vol 399 ◽  
pp. 184-198 ◽  
Author(s):  
S. Manohar ◽  
P.V. Ramchander ◽  
R. Salvi ◽  
G.M. Seigel
Keyword(s):  
Cochlear Nucleus ◽  
Noise Exposure ◽  
Synaptic Reorganization ◽  
Intense Noise

Effects of L-Baclofen and D-Baclofen on the Auditory System: A Study of Click-Evoked Potentials from the Inferior Colliculus in the Rat

1995 ◽  
Vol 104 (5) ◽  
pp. 399-404 ◽  
Author(s):  
William S. Szczepaniak ◽  
Aage R. Møller
Keyword(s):  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Auditory Pathway ◽  
Detectable Effect ◽  
Potential Treatment ◽  
Racemic Form ◽  
System A ◽  
Auditory Disorders ◽  
Severe Tinnitus ◽  
Second Peak

The drug baclofen is a potential treatment for severe tinnitus, but its action in relieving tinnitus is not known. Baclofen is available as an approved drug only in racemic form with about equal content of the two enantiomers. In the present paper we show that l-baclofen causes a considerable (40.7%) suppression of the amplitude of the second peak in the click-evoked response from the cochlear nucleus. Bipolar recordings from the external nucleus of the inferior colliculus showed that l-baclofen caused a reduction in the amplitude of three or four distinct peaks in this response. d-Baclofen had no detectable effect on the response from the cochlear nucleus, and had only a slight effect on one component of the response from the external nucleus of the inferior colliculus. The demonstrated effect of l-baclofen on excitation in the ascending auditory pathway indicates that this drug may be a potential treatment for hyperactive auditory disorders such as tinnitus and hyperacusis.

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