1
|
Baldassano JF, MacLeod KM. Kv1 channels regulate variations in spike patterning and temporal reliability in the avian cochlear nucleus angularis. J Neurophysiol 2022; 127:116-129. [PMID: 34817286 PMCID: PMC8742726 DOI: 10.1152/jn.00460.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Diverse physiological phenotypes in a neuronal population can broaden the range of computational capabilities within a brain region. The avian cochlear nucleus angularis (NA) contains a heterogeneous population of neurons whose variation in intrinsic properties results in electrophysiological phenotypes with a range of sensitivities to temporally modulated input. The low-threshold potassium conductance (GKLT) is a key feature of neurons involved in fine temporal structure coding for sound localization, but a role for these channels in intensity or spectrotemporal coding has not been established. To determine whether GKLT affects the phenotypical variation and temporal properties of NA neurons, we applied dendrotoxin-I (DTX), a potent antagonist of Kv1-type potassium channels, to chick brain stem slices in vitro during whole cell patch-clamp recordings. We found a cell-type specific subset of NA neurons that was sensitive to DTX: single-spiking NA neurons were most profoundly affected, as well as a subset of tonic-firing neurons. Both tonic I (phasic onset bursting) and tonic II (delayed firing) neurons showed DTX sensitivity in their firing rate and phenotypical firing pattern. Tonic III neurons were unaffected. Spike time reliability and fluctuation sensitivity measured in DTX-sensitive NA neurons was also reduced with DTX. Finally, DTX reduced spike threshold adaptation in these neurons, suggesting that GKLT contributes to the temporal properties that allow coding of rapid changes in the inputs to NA neurons. These results suggest that variation in Kv1 channel expression may be a key factor in functional diversity in the avian cochlear nucleus.NEW & NOTEWORTHY The dendrotoxin-sensitive voltage-gated potassium conductance typically associated with neuronal coincidence detection in the timing pathway for sound localization is demonstrated to affect spiking patterns and temporal input sensitivity in the intensity pathway in the avian auditory brain stem. The Kv1-family channels appear to be present in a subset of cochlear nucleus angularis neurons, regulate spike threshold dynamics underlying high-pass membrane filtering, and contribute to intrinsic firing diversity.
Collapse
|
2
|
Takahashi M, Sanchez JT. Effects of Neurotrophin-3 on Intrinsic Neuronal Properties at a Central Auditory Structure. Neurosci Insights 2020; 15:2633105520980442. [PMID: 33354669 PMCID: PMC7734498 DOI: 10.1177/2633105520980442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 11/23/2020] [Indexed: 11/15/2022] Open
Abstract
Neurotrophins, a class of growth factor proteins that control neuronal proliferation, morphology, and apoptosis, are found ubiquitously throughout the nervous system. One particular neurotrophin (NT-3) and its cognate tyrosine receptor kinase (TrkC) have recently received attention as a possible therapeutic target for synaptopathic sensorineural hearing loss. Additionally, research shows that NT-3-TrkC signaling plays a role in establishing the sensory organization of frequency topology (ie, tonotopic order) in the cochlea of the peripheral inner ear. However, the neurotrophic effects of NT-3 on central auditory properties are unclear. In this study we examined whether NT-3-TrkC signaling affects the intrinsic electrophysiological properties at a first-order central auditory structure in chicken, known as nucleus magnocellularis (NM). Here, the expression pattern of specific neurotrophins is well known and tightly regulated. By using whole-cell patch-clamp electrophysiology, we show that NT-3 application to brainstem slices does not affect intrinsic properties of high-frequency neuronal regions but had robust effects for low-frequency neurons, altering voltage-dependent potassium functions, action potential repolarization kinetics, and passive membrane properties. We suggest that NT-3 may contribute to the precise establishment and organization of tonotopy in the central auditory pathway by playing a specialized role in regulating the development of intrinsic neuronal properties of low-frequency NM neurons.
Collapse
Affiliation(s)
- Momoko Takahashi
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
| | - Jason Tait Sanchez
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- The Hugh Knowles Hearing Research Center, Northwestern University, Evanston, IL, USA
| |
Collapse
|
3
|
Müller MK, Jovanovic S, Keine C, Radulovic T, Rübsamen R, Milenkovic I. Functional Development of Principal Neurons in the Anteroventral Cochlear Nucleus Extends Beyond Hearing Onset. Front Cell Neurosci 2019; 13:119. [PMID: 30983974 PMCID: PMC6447607 DOI: 10.3389/fncel.2019.00119] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/11/2019] [Indexed: 01/23/2023] Open
Abstract
Sound information is transduced into graded receptor potential by cochlear hair cells and encoded as discrete action potentials of auditory nerve fibers. In the cochlear nucleus, auditory nerve fibers convey this information through morphologically distinct synaptic terminals onto bushy cells (BCs) and stellate cells (SCs) for processing of different sound features. With expanding use of transgenic mouse models, it is increasingly important to understand the in vivo functional development of these neurons in mice. We characterized the maturation of spontaneous and acoustically evoked activity in BCs and SCs by acquiring single-unit juxtacellular recordings between hearing onset (P12) and young adulthood (P30) of anesthetized CBA/J mice. In both cell types, hearing sensitivity and characteristic frequency (CF) range are mostly adult-like by P14, consistent with rapid maturation of the auditory periphery. In BCs, however, some physiological features like maximal firing rate, dynamic range, temporal response properties, recovery from post-stimulus depression, first spike latency (FSL) and encoding of sinusoid amplitude modulation undergo further maturation up to P18. In SCs, the development of excitatory responses is even more prolonged, indicated by a gradual increase in spontaneous and maximum firing rates up to P30. In the same cell type, broadly tuned acoustically evoked inhibition is immediately effective at hearing onset, covering the low- and high-frequency flanks of the excitatory response area. Together, these data suggest that maturation of auditory processing in the parallel ascending BC and SC streams engages distinct mechanisms at the first central synapses that may differently depend on the early auditory experience.
Collapse
Affiliation(s)
- Maria Katharina Müller
- Carl Ludwig Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Sasa Jovanovic
- Carl Ludwig Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Christian Keine
- Carver College of Medicine, Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA, United States.,Institute of Biology, Faculty of Life Sciences, University of Leipzig, Leipzig, Germany
| | - Tamara Radulovic
- Carl Ludwig Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany.,Carver College of Medicine, Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA, United States
| | - Rudolf Rübsamen
- Institute of Biology, Faculty of Life Sciences, University of Leipzig, Leipzig, Germany
| | - Ivan Milenkovic
- Carl Ludwig Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany.,School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| |
Collapse
|
4
|
Lu T, Wade K, Hong H, Sanchez JT. Ion channel mechanisms underlying frequency-firing patterns of the avian nucleus magnocellularis: A computational model. Channels (Austin) 2017; 11:444-458. [PMID: 28481659 PMCID: PMC5626364 DOI: 10.1080/19336950.2017.1327493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We have previously shown that late-developing avian nucleus magnocellularis (NM) neurons (embryonic [E] days 19–21) fire action potentials (APs) that resembles a band-pass filter in response to sinusoidal current injections of varying frequencies. NM neurons located in the mid- to high-frequency regions of the nucleus fire preferentially at 75 Hz, but only fire a single onset AP to frequency inputs greater than 200 Hz. Surprisingly, NM neurons do not fire APs to sinusoidal inputs less than 20 Hz regardless of the strength of the current injection. In the present study we evaluated intrinsic mechanisms that prevent AP generation to low frequency inputs. We constructed a computational model to simulate the frequency-firing patterns of NM neurons based on experimental data at both room and near physiologic temperatures. The results from our model confirm that the interaction among low- and high-voltage activated potassium channels (KLVA and KHVA, respectively) and voltage dependent sodium channels (NaV) give rise to the frequency-firing patterns observed in vitro. In particular, we evaluated the regulatory role of KLVA during low frequency sinusoidal stimulation. The model shows that, in response to low frequency stimuli, activation of large KLVA current counterbalances the slow-depolarizing current injection, likely permitting NaV closed-state inactivation and preventing the generation of APs. When the KLVA current density was reduced, the model neuron fired multiple APs per sinusoidal cycle, indicating that KLVA channels regulate low frequency AP firing of NM neurons. This intrinsic property of NM neurons may assist in optimizing response to different rates of synaptic inputs.
Collapse
Affiliation(s)
- Ting Lu
- a Roxelyn and Richard Pepper Department of Communication Sciences and Disorders , Northwestern University , Evanston , IL , USA
| | - Kirstie Wade
- a Roxelyn and Richard Pepper Department of Communication Sciences and Disorders , Northwestern University , Evanston , IL , USA
| | - Hui Hong
- a Roxelyn and Richard Pepper Department of Communication Sciences and Disorders , Northwestern University , Evanston , IL , USA
| | - Jason Tait Sanchez
- a Roxelyn and Richard Pepper Department of Communication Sciences and Disorders , Northwestern University , Evanston , IL , USA.,b Department of Neurobiology , Northwestern University , Evanston , IL , USA.,c The Hugh Knowles Hearing Research Center , Northwestern University , Evanston , IL , USA
| |
Collapse
|
5
|
Distinct Neural Properties in the Low-Frequency Region of the Chicken Cochlear Nucleus Magnocellularis. eNeuro 2017; 4:eN-NWR-0016-17. [PMID: 28413822 PMCID: PMC5388668 DOI: 10.1523/eneuro.0016-17.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/17/2017] [Accepted: 03/05/2017] [Indexed: 12/03/2022] Open
Abstract
Topography in the avian cochlear nucleus magnocellularis (NM) is represented as gradually increasing characteristic frequency (CF) along the caudolateral-to-rostromedial axis. In this study, we characterized the organization and cell biophysics of the caudolateral NM (NMc) in chickens (Gallus gallus). Examination of cellular and dendritic architecture first revealed that NMc contains small neurons and extensive dendritic processes, in contrast to adendritic, large neurons located more rostromedially. Individual dye-filling study further demonstrated that NMc is divided into two subregions, with NMc2 neurons having larger and more complex dendritic fields than NMc1. Axonal tract tracing studies confirmed that NMc1 and NMc2 neurons receive afferent inputs from the auditory nerve and the superior olivary nucleus, similar to the adendritic NM. However, the auditory axons synapse with NMc neurons via small bouton-like terminals, unlike the large end bulb synapses on adendritic NM neurons. Immunocytochemistry demonstrated that most NMc2 neurons express cholecystokinin but not calretinin, distinct from NMc1 and adendritic NM neurons that are cholecystokinin negative and mostly calretinin positive. Finally, whole-cell current clamp recordings revealed that NMc neurons require significantly lower threshold current for action potential generation than adendritic NM neurons. Moreover, in contrast to adendritic NM neurons that generate a single-onset action potential, NMc neurons generate multiple action potentials to suprathreshold sustained depolarization. Taken together, our data indicate that NMc contains multiple neuron types that are structurally, connectively, molecularly, and physiologically different from traditionally defined NM neurons, emphasizing specialized neural properties for processing low-frequency sounds.
Collapse
|
6
|
Hong H, Rollman L, Feinstein B, Sanchez JT. Developmental Profile of Ion Channel Specializations in the Avian Nucleus Magnocellularis. Front Cell Neurosci 2016; 10:80. [PMID: 27065805 PMCID: PMC4811932 DOI: 10.3389/fncel.2016.00080] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/14/2016] [Indexed: 11/18/2022] Open
Abstract
Ultrafast and temporally precise action potentials (APs) are biophysical specializations of auditory brainstem neurons; properties necessary for encoding sound localization and communication cues. Fundamental to these specializations are voltage dependent potassium (KV) and sodium (NaV) ion channels. Here, we characterized the functional development of these ion channels and quantified how they shape AP properties in the avian cochlear nucleus magnocellularis (NM). We report that late developing NM neurons (embryonic [E] days 19–21) generate fast APs that reliably phase lock to sinusoidal inputs at 75 Hz. In contrast, early developing neurons (<E12) have slower and less reliable APs that preferentially fire to lower frequencies (5–10 Hz). With development, the membrane time constant of NM neurons became faster, while input resistance and capacitance decreased. Change in input resistance was due to a 2-fold increase in KV current from E10 to E21 and when high-voltage activated potassium (K+HVA) channels were blocked, APs for all ages became significantly slower. This was most evident for early developing neurons where the ratio of K+HVA current accounted for ~85% of the total KV response. This ratio dropped to ~50% for late developing neurons, suggesting a developmental upregulation of low-voltage activated potassium (K+LVA) channels. Indeed, blockade of K+LVA eliminated remaining current and increased neural excitability for late developing neurons. We also report developmental changes in the amplitude, kinetics and voltage dependence of NaV currents. For early developing neurons, increase in NaV current amplitude was due to channel density while channel conductance dominated for late developing neurons. From E10 to E21, NaV channel currents became faster but differed in their voltage dependence; early developing neurons (<E16) had similar NaV channel inactivation voltages while late developing NM neurons (>E19) contained NaV channels that inactivate at more negative voltages, suggesting alterations in NaV channel subtypes. Taken together, our results indicate that the refinement of passive and active ion channel properties operate differentially in order to develop fast and reliable APs in the avian NM.
Collapse
Affiliation(s)
- Hui Hong
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University Evanston, IL, USA
| | - Lisia Rollman
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University Evanston, IL, USA
| | - Brooke Feinstein
- Department of Neurobiology and Interdepartmental Neuroscience Program, Weinberg College of Arts and Sciences, Northwestern University Evanston, IL, USA
| | - Jason Tait Sanchez
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern UniversityEvanston, IL, USA; Department of Neurobiology and Interdepartmental Neuroscience Program, Weinberg College of Arts and Sciences, Northwestern UniversityEvanston, IL, USA
| |
Collapse
|