Temporal and Frequency Characteristics of Cartwheel Cells in the Dorsal Cochlear Nucleus of the Awake Mouse

2007 ◽  
Vol 98 (2) ◽  
pp. 744-756 ◽  
Author(s):  
Christine V. Portfors ◽  
Patrick D. Roberts
Keyword(s):  
Auditory Processing ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Active Role ◽  
Auditory Pathway ◽  
Dorsal Cochlear Nucleus ◽  
Central Auditory Processing ◽  
Complex Frequency ◽  
Principal Cells ◽  
Cartwheel Cells

The dorsal cochlear nucleus (DCN) is an initial site of central auditory processing and also the first site of multisensory convergence in the auditory pathway. The auditory nerve imparts a tonotopic frequency organization on the responses of principal cells in the DCN. Cartwheel cells modify the responses of principal cells, but they do not receive direct auditory nerve input. This study shows that cartwheel cells respond well to tonal stimuli in the awake mouse and they have a well-defined characteristic frequency that corresponds to the tonotopic organization of the DCN. The auditory responses of cartwheel cells exhibit complex spectrotemporal responses to tones, with excitation and inhibition modulating the firing patterns in both frequency and time after onset of the stimulus. Temporal responses to best-frequency tones are highly variable between cartwheel cells, but a simple model is used to unify this variability as differences in the timing of synaptic currents. Cartwheel cell responses to two-tone stimuli show that interactions from different frequencies affect the output of cartwheel cells. The results suggest that at this primary auditory structure, processing of sound at one frequency can be modified by sounds of different frequency. These complex frequency and temporal interactions in cartwheel cells suggest that these neurons play an active role in basic sound processing.

In Vitro Studies of Neuromodulation and Plasticity in the Dorsal Cochlear Nucleus

2018 ◽  
pp. 122-142 ◽  
Author(s):  
Laurence O. Trussell
Keyword(s):  
Synaptic Plasticity ◽  
Auditory Processing ◽  
Cochlear Nucleus ◽  
Cell Types ◽  
Auditory Pathway ◽  
Dorsal Cochlear Nucleus ◽  
Membrane Properties ◽  
Auditory Input ◽  
Dynamic Tuning

The dorsal cochlear nucleus (DCN), a division of the cochlear nuclear complex, has been the subject of intense interest for its role in auditory processing and hearing disorders. The tonotopic layout of DCN principal cells and the refinement of processing of auditory signals by interneurons are together thought to permit encoding of sound source elevation. However, the many cell types and complex connectivity of the DCN suggest more diverse functions than localization. A prominent non-auditory input to the DCN has been proposed to assist in such functions as orienting to sounds of interest, detecting moving sounds, or cancelling self-generated sounds. Synaptic plasticity in the DCN may be essential for dynamic tuning of non-auditory input. Indeed, long-term changes in synaptic or membrane properties could underlie tinnitus, which is associated with hyperactivity in the DCN in some animal models. Finally, the DCN is invested with wide-ranging neuromodulatory mechanisms, suggesting that changes in the behavioral state of animals associated with such neuromodulatory systems might alter sensory processing at the earliest stages of the auditory pathway. This review will focus on studies that have utilized the in vitro brain slice approach to identify basic mechanisms of synaptic plasticity and neuromodulation in the DCN.

scholarly journals Two Distinct Types of Inhibition Mediated by Cartwheel Cells in the Dorsal Cochlear Nucleus

2009 ◽  
Vol 102 (2) ◽  
pp. 1287-1295 ◽  
Author(s):  
Jaime G. Mancilla ◽  
Paul B. Manis
Keyword(s):  
Cochlear Nucleus ◽  
Reversal Potential ◽  
Dorsal Cochlear Nucleus ◽  
Synaptic Function ◽  
Half Width ◽  
Neonatal Rat ◽  
Projection Neurons ◽  
Paired Pulse ◽  
Dependent Inhibition ◽  
Cartwheel Cells

Individual neurons have been shown to exhibit target cell-specific synaptic function in several brain areas. The time course of the postsynaptic conductances (PSCs) strongly influences the dynamics of local neural networks. Cartwheel cells (CWCs) are the most numerous inhibitory interneurons in the dorsal cochlear nucleus (DCN). They are excited by parallel fiber synapses, which carry polysensory information, and in turn inhibit other CWCs and the main projection neurons of the DCN, pyramidal cells (PCs). CWCs have been implicated in “context-dependent” inhibition, producing either depolarizing (other CWCs) or hyperpolarizing (PCs) post synaptic potentials. In the present study, we used paired whole cell recordings to examine target-dependent inhibition from CWCs in neonatal rat DCN slices. We found that CWC inhibitory postsynaptic potentials (IPSPs) onto PCs are large (1.3 mV) and brief (half-width = 11.8 ms), whereas CWC IPSPs onto other CWCs are small (0.2 mV) and slow (half-width = 36.8 ms). Evoked IPSPs between CWCs exhibit paired-pulse facilitation, while CWC IPSPs onto PCs exhibit paired-pulse depression. Perforated-patch recordings showed that spontaneous IPSPs in CWCs are hyperpolarizing at rest with a mean estimated reversal potential of −67 mV. Spontaneous IPSCs were smaller and lasted longer in CWCs than in PCs, suggesting that the kinetics of the receptors are different in the two cell types. These results reveal that CWCs play a dual role in the DCN. The CWC-CWC network interactions are slow and sensitive to the average rate of CWC firing, whereas the CWC-PC network is fast and sensitive to transient changes in CWC firing.

scholarly journals Molecular Layer Inhibitory Interneurons Provide Feedforward and Lateral Inhibition in the Dorsal Cochlear Nucleus

2010 ◽  
Vol 104 (5) ◽  
pp. 2462-2473 ◽  
Author(s):  
Michael T. Roberts ◽  
Laurence O. Trussell
Keyword(s):  
Brain Stem ◽  
Lateral Inhibition ◽  
Cochlear Nucleus ◽  
Molecular Layer ◽  
Dorsal Cochlear Nucleus ◽  
Inhibitory Input ◽  
Auditory Information ◽  
Parallel Fibers ◽  
Sensory Inputs ◽  
Cartwheel Cells

In the outer layers of the dorsal cochlear nucleus, a cerebellum-like structure in the auditory brain stem, multimodal sensory inputs drive parallel fibers to excite both principal (fusiform) cells and inhibitory cartwheel cells. Cartwheel cells, in turn, inhibit fusiform cells and other cartwheel cells. At the microcircuit level, it is unknown how these circuit components interact to modulate the activity of fusiform cells and thereby shape the processing of auditory information. Using a variety of approaches in mouse brain stem slices, we investigated the synaptic connectivity and synaptic strength among parallel fibers, cartwheel cells, and fusiform cells. In paired recordings of spontaneous and evoked activity, we found little overlap in parallel fiber input to neighboring neurons, and activation of multiple parallel fibers was required to evoke or alter action potential firing in cartwheel and fusiform cells. Thus neighboring neurons likely respond best to distinct subsets of sensory inputs. In contrast, there was significant overlap in inhibitory input to neighboring neurons. In recordings from synaptically coupled pairs, cartwheel cells had a high probability of synapsing onto nearby fusiform cells or other nearby cartwheel cells. Moreover, single cartwheel cells strongly inhibited spontaneous firing in single fusiform cells. These synaptic relationships suggest that the set of parallel fibers activated by a particular sensory stimulus determines whether cartwheel cells provide feedforward or lateral inhibition to their postsynaptic targets.

Vertical Cell Responses to Sound in Cat Dorsal Cochlear Nucleus

1999 ◽  
Vol 82 (2) ◽  
pp. 1019-1032 ◽  
Author(s):  
William S. Rhode
Keyword(s):  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Molecular Layer ◽  
Broadband Noise ◽  
Dorsal Cochlear Nucleus ◽  
Type Ii ◽  
Fusiform Cell ◽  
Sound Sources ◽  
Tuning Curves ◽  
Axonal Arbors

The dorsal cochlear nucleus receives input from the auditory nerve and relays acoustic information to the inferior colliculus. Its principal cells receive two systems of inputs. One system through the molecular layer carries multimodal information that is processed through a neuronal circuit that resembles the cerebellum. A second system through the deep layer carries primary auditory nerve input, some of which is relayed through interneurons. The present study reveals the morphology of individual interneurons and their local axonal arbors and how these inhibitory interneurons respond to sound. Vertical cells lie beneath the fusiform cell layer. Their dendritic and axonal arbors are limited to an isofrequency lamina. They give rise to pericellular nests around the base of fusiform cells and their proximal basal dendrites. These cells exhibit an onset-graded response to short tones and have response features defined as type II. They have tuning curves that are closed contours (0 shaped), thresholds ∼27 dB SPL, spontaneous firing rates of ∼0 spikes/s, and they respond weakly or not at all to broadband noise, as described for type II units. Their responses are nonmonotonic functions of intensity with peak responses between 30 and 60 dB SPL. They also show a preference for the high-to-low direction of a frequency sweep. It has been suggested that these circuits may be involved in the processing of spectral cues for the localization of sound sources.

R446 – Rostral Cochlear Nucleus Changes After Cochlear Ablation

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P194-P194 ◽  
Author(s):  
Kyle Robinson ◽  
Donald A Godfrey ◽  
Matthew A. Godfrey
Keyword(s):  
Auditory Processing ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
High Performance ◽  
Nerve Fibers ◽  
Average Concentration ◽  
Gamma Aminobutyric Acid ◽  
Freeze Dried ◽  
Concentration Changes ◽  
Temporal Bones

Problem Identification of neurotransmitter concentration changes occurring in the rostral anterior ventral cochlear nucleus (AVCN) following transection of the auditory nerve within the cochlea. Methods Chinchillas with cochlear ablations, as well as sham-lesioned chinchillas, were euthanized at times ranging from 3 to 84 days post ablation. Both temporal bones and brains were saved. Temporal bones were fixed, embedded in paraffin and sectioned to document the completeness of the cochlear lesion. Brain portions containing the cochlear nuclei were frozen-sectioned, and sections were freeze dried. Freeze-dried sections were microdissected into samples of AVCN for high performance liquid chromatography (HPLC) assay of 12 amino acid concentrations. Results The average concentration of glutamate, the most likely neurotransmitter of auditory nerve fibers, declined in the lesioned-side rostral AVCN by about 25% at 15 days. This decrease was maintained through 31 days post ablation and became bilateral at 83 days. There was no decrease in the adjacent granular region. Larger lesioned-side decreases, approaching 50%, were found more caudally in the AVCN at 31 days post ablation. The average concentration of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) decreased bilaterally by 15–25% at 3 through 15 days post ablation. Conclusion The degeneration of the central portion of the auditory nerve following mechanical ablation of the cochlea is accompanied by decreases of glutamate concentration on the lesioned side but bilateral decreases of GABA in the rostral part of the AVCN. These decreases were smaller than those reported previously for the posteroventral cochlear nucleus (PVCN). However, changes more caudally in AVCN approach those found in PVCN. Significance Our results are consistent with other evidence that damage to the cochlea leads to neurotransmitter changes in the central auditory system. The smaller changes in AVCN than in PVCN may correlate with different types of auditory processing in these two regions. Support The American Tinnitus Association and the University of Toledo Foundation.

scholarly journals Case Report: Auditory Neuropathy and Central Auditory Processing Deficits in a Neuro-Otological Case-Study of Infratentorial Superficial Siderosis

2021 ◽  
Vol 11 ◽  
Author(s):  
Natallia Kharytaniuk ◽  
Peter Cowley ◽  
David J. Werring ◽  
Doris-Eva Bamiou
Keyword(s):  
Magnetic Resonance ◽  
Auditory Processing ◽  
Auditory Pathway ◽  
Magnetic Resonance Images ◽  
Auditory Neuropathy ◽  
Self Report ◽  
Response To Treatment ◽  
Superficial Siderosis ◽  
Central Auditory Processing ◽  
Processing Deficits

Hearing and balance impairment are the most frequently reported features of infratentorial (classical) superficial siderosis (iSS). There are few comprehensive descriptions of audiovestibular function in iSS and therefore limited understanding of the affected segment(s) of the audiovestibular pathway. In addition, monitoring disease progression and response to treatment is challenging and currently mainly guided by subjective patient reports and magnetic resonance imaging. To the best of our knowledge, there have been no previous reports assessing central auditory function in iSS. We describe such findings in a patient with iSS in an attempt to precisely localize the site of the audiovestibular dysfunction, determine its severity and functional impact. We confirm the presence of (asymmetrical) auditory neuropathy and identify central auditory processing deficits, suggesting involvement of the central auditory pathway beyond the brainstem. We correlate the audiological and vestibular findings with self-report measures and the siderosis appearances on brain magnetic resonance images.

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.

Neuronal circuits associated with the output of the dorsal cochlear nucleus through fusiform cells

1994 ◽  
Vol 71 (3) ◽  
pp. 914-930 ◽  
Author(s):  
S. Zhang ◽  
D. Oertel
Keyword(s):  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Nerve Fibers ◽  
Dorsal Cochlear Nucleus ◽  
Resting Potential ◽  
Temporal Association ◽  
Common Source ◽  
Excitatory Postsynaptic Potential ◽  
Current Voltage ◽  
Synaptic Responses

1. Intracellular recordings were made from 21 anatomically identified fusiform cells in the dorsal cochlear nucleus (DCN) of mice in slices. The aim of the experiments was to dissect the synaptic responses to shocks of the auditory nerve to correlate functional characteristics with the different classes of synaptic inputs. 2. When depolarized from rest (-57 +/- 5 mV) with current pulses, fusiform cells fired regular, overshooting action potentials that were followed by two undershoots. The frequency of firing increased with the strength of injected current by between 100 and 300 spikes/s/nA. The current-voltage relationship rectified between 10 and 15 mV below the resting potential. The slopes of current-voltage relationships of fusiform cells in the range between the resting potential and 10 mV hyperpolarization indicated an average input resistance of 86 +/- 37 M omega. 3. In each of the labeled fusiform cells frequent, spontaneous inhibitory postsynaptic potentials (IPSPs) were recorded singly or in bursts. Some, but not all, IPSPs were preceded by a slowly rising excitatory postsynaptic potential (EPSP). The temporal association of spontaneous EPSPs and IPSPs suggests that they are driven by a common source, possibly granule cells. 4. Shocks to the auditory nerve evoked synaptic responses consisting of early (1 to approximately 10 ms) and late (approximately 10 to 100 ms) components. 6,7-Dinitroquinoxaline-2,3-dione (DNQX) at 20 to 40 microM eliminated all detectable excitation and all late IPSPs. Late bursts of IPSPs, therefore, are mediated through a polysynaptic pathway that includes a DNQX-sensitive stage. Strong shocks to the nerve root elicited single monosynaptic IPSPs, indicating that inhibitory interneurons have processes close to the auditory nerve. Strychnine at 0.5 microM eliminated all detectable inhibition. 6. Cuts through the posteroventral cochlear nucleus (PVCN), which severed the descending branches of auditory nerve fibers, eliminated early EPSPs and IPSPs leaving late, slowly rising EPSPs and bursts of IPSPs in responses to shocks of the auditory nerve. Late, slowly rising EPSPs and bursts of IPSPs, as well as monosynaptic IPSPs, could also be evoked by stimulating the anteroventral cochlear nucleus (AVCN). 7. Focal applications of glutamate evoked excitation and inhibition from many parts of a slice, with patterns varying among cells, indicating that fusiform cells receive inputs through several groups of interneurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document