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.

scholarly journals Expression and Localization of Kv1.1 and Kv3.1b Potassium Channels in the Cochlear Nucleus and Inferior Colliculus after Long-Term Auditory Deafferentation

2020 ◽  
Vol 10 (1) ◽  
pp. 35 ◽  
Author(s):  
Clara Poveda ◽  
Maria Valero ◽  
Marianny Pernia ◽  
Juan Alvarado ◽  
David Ryugo ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Protein Expression ◽  
Inferior Colliculus ◽  
Auditory Processing ◽  
Cochlear Nucleus ◽  
Auditory Pathway ◽  
Cellular Mechanisms ◽  
Auditory Deprivation ◽  
Central Auditory Neurons

Deafness affects the expression and distribution of voltage-dependent potassium channels (Kvs) of central auditory neurons in the short-term, i.e., hours to days, but the consequences in the expression of Kvs after long-term deafness remain unknown. We tested expression and distribution of Kv1.1 and Kv3.1b, key for auditory processing, in the rat cochlear nucleus (CN), and in the inferior colliculus (IC), at 1, 15 and 90 days after mechanical lesion of the cochlea, using a combination of qRT-PCR and Western blot in the whole CN, along with semi-quantitative immunocytochemistry in the AVCN, where the role of both Kvs in the control of excitability for accurate auditory timing signal processing is well established. Neither Kv1.1/Kv3.1b mRNA or protein expression changed significantly in the CN between 1 and 15 days after deafness. At 90 days post-lesion, however, mRNA and protein expression for both Kvs increased, suggesting that regulation of Kv1.1 and Kv3.1b expression is part of cellular mechanisms for long-term adaptation to auditory deprivation in the CN. Consistent with these findings, immunocytochemistry showed increased labeling intensity for both Kvs in the AVCN at day 90 after cochlear lesion. This increase argues that up-regulation of Kv1.1 and Kv3.1b in AVCN neurons may be required to adapt intrinsic excitability to altered input over the long term after auditory deprivation. Contrary to these findings in the CN, expression levels of Kv1.1 and Kv3.1b in the IC did not undergo major changes after cochlear lesion. In particular, there was no evidence of long-term up-regulation of either Kv1.1 or Kv3.1b, supporting that such post-lesion adaptive mechanism may not be needed in the IC. These results reveal that post-lesion adaptations do not necessarily involve stereotyped plastic mechanisms along the entire auditory pathway.

scholarly journals Changes in microRNA Expression in the Cochlear Nucleus and Inferior Colliculus after Acute Noise-Induced Hearing Loss

2020 ◽  
Vol 21 (22) ◽  
pp. 8792
Author(s):  
Sohyeon Park ◽  
Seung Hee Han ◽  
Byeong-Gon Kim ◽  
Myung-Whan Suh ◽  
Jun Ho Lee ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inferior Colliculus ◽  
Neural Plasticity ◽  
Cochlear Nucleus ◽  
Organ Of Corti ◽  
Auditory Pathway ◽  
Noise Induced Hearing Loss ◽  
Candidate Mirnas ◽  
Central Auditory Pathway

Noise-induced hearing loss (NIHL) can lead to secondary changes that induce neural plasticity in the central auditory pathway. These changes include decreases in the number of synapses, the degeneration of auditory nerve fibers, and reorganization of the cochlear nucleus (CN) and inferior colliculus (IC) in the brain. This study investigated the role of microRNAs (miRNAs) in the neural plasticity of the central auditory pathway after acute NIHL. Male Sprague–Dawley rats were exposed to white band noise at 115 dB for 2 h, and the auditory brainstem response (ABR) and morphology of the organ of Corti were evaluated on days 1 and 3. Following noise exposure, the ABR threshold shift was significantly smaller in the day 3 group, while wave II amplitudes were significantly larger in the day 3 group compared to the day 1 group. The organ of Corti on the basal turn showed evidence of damage and the number of surviving outer hair cells was significantly lower in the basal and middle turn areas of the hearing loss groups relative to controls. Five and three candidate miRNAs for each CN and IC were selected based on microarray analysis and quantitative reverse transcription PCR (RT-qPCR). The data confirmed that even short-term acoustic stimulation can lead to changes in neuroplasticity. Further studies are needed to validate the role of these candidate miRNAs. Such miRNAs may be used in the early diagnosis and treatment of neural plasticity of the central auditory pathway after acute NIHL.

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.

Fast Inhibition Alters First Spike Timing in Auditory Brainstem Neurons

2004 ◽  
Vol 92 (4) ◽  
pp. 2615-2621 ◽  
Author(s):  
Antonio G. Paolini ◽  
Janine C. Clarey ◽  
Karina Needham ◽  
Graeme M. Clark
Keyword(s):  
Lateral Inhibition ◽  
Cochlear Nucleus ◽  
Stellate Cell ◽  
Discharge Rate ◽  
Stellate Cells ◽  
Auditory Pathway ◽  
Auditory Brainstem ◽  
Spike Timing ◽  
Inhibitory Neurons

Within the first processing site of the central auditory pathway, inhibitory neurons (D stellate cells) broadly tuned to tonal frequency project on narrowly tuned, excitatory output neurons (T stellate cells). The latter is thought to provide a topographic representation of sound spectrum, whereas the former is thought to provide lateral inhibition that improves spectral contrast, particularly in noise. In response to pure tones, the overall discharge rate in T stellate cells is unlikely to be suppressed dramatically by D stellate cells because they respond primarily to stimulus onset and provide fast, short-duration inhibition. In vivo intracellular recordings from the ventral cochlear nucleus (VCN) showed that, when tones were presented above or below the characteristic frequency (CF) of a T stellate neuron, they were inhibited during depolarization. This resulted in a delay in the initial action potential produced by T stellate cells. This ability of fast inhibition to alter the first spike timing of a T stellate neuron was confirmed by electrically activating the D stellate cell pathway that arises in the contralateral cochlear nucleus. Delay was also induced when two tones were presented: one at CF and one outside the frequency response area of the T stellate neuron. These findings suggest that the traditional view of lateral inhibition within the VCN should incorporate delay as one of its principle outcomes.

scholarly journals Biomimetic Sonar for Electrical Activation of the Auditory Pathway

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
D. Menniti ◽  
S. A. Pullano ◽  
M. G. Bianco ◽  
R. Citraro ◽  
E. Russo ◽  
...  
Keyword(s):  
Spatial Information ◽  
Electronic Device ◽  
Principal Component ◽  
Auditory Pathway ◽  
Brain Response ◽  
Implanted Electrodes ◽  
System A ◽  
Signal Features ◽  
New Perspective ◽  
Rate Frequency

Relying on the mechanism of bat’s echolocation system, a bioinspired electronic device has been developed to investigate the cortical activity of mammals in response to auditory sensorial stimuli. By means of implanted electrodes, acoustical information about the external environment generated by a biomimetic system and converted in electrical signals was delivered to anatomically selected structures of the auditory pathway. Electrocorticographic recordings showed that cerebral activity response is highly dependent on the information carried out by ultrasounds and is frequency-locked with the signal repetition rate. Frequency analysis reveals that delta and beta rhythm content increases, suggesting that sensorial information is successfully transferred and integrated. In addition, principal component analysis highlights how all the stimuli generate patterns of neural activity which can be clearly classified. The results show that brain response is modulated by echo signal features suggesting that spatial information sent by biomimetic sonar is efficiently interpreted and encoded by the auditory system. Consequently, these results give new perspective in artificial environmental perception, which could be used for developing new techniques useful in treating pathological conditions or influencing our perception of the surroundings.

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