scholarly journals Dendritic speeding of synaptic potentials in an auditory brainstem principal neuron

2019 ◽  
Author(s):  
Geetha Srinivasan ◽  
Andre Dagostin ◽  
Richardson N. Leão ◽  
Veeramuthu Balakrishnan ◽  
Paul Holcomb ◽  
...  
Keyword(s):  
High Frequency ◽  
Afferent Fiber ◽  
Input Resistance ◽  
Auditory Brainstem ◽  
Dendritic Morphology ◽  
Functional Roles ◽  
Principal Cells ◽  
Medial Nucleus ◽  
Mature Neurons ◽  
Confocal Fluorescence Imaging

AbstractPrincipal cells of the medial nucleus of the trapezoid body (MNTB) in the mammalian auditory brainstem receive most of their strong synaptic inputs directly on the cell soma. However, these neurons also grow extensive dendrites during the first four postnatal weeks. What are the functional roles of these dendrites? We studied the morphology and growth of the dendrites in the mouse MNTB using both electron microscopy and confocal fluorescence imaging from postnatal day 9 (P9; pre-hearing) to P30. The soma of principal cells sprouted 1 to 3 thin dendrites (diameter ~ 1.5 microns) by P21 to P30. Each dendrite bifurcated into 2-3 branches and spanned an overall distance of about 80 to 200 microns. By contrast, at P9-11 the soma had 1 to 2 dendrites that extended for only 25 microns on average. Patch clamp experiments revealed that the growth of dendrites during development correlates with a progressive decrease in the input resistance, whereas acute removal of dendrites during brain slicing leads to higher input resistances. Accordingly, recordings of excitatory postsynaptic potentials (EPSPs) evoked by afferent fiber stimulation show that EPSP decay is faster in P21-24 neurons with intact dendrites than in neurons without dendrites. This dendritic speeding of the EPSP reduces the decay time constant 5-fold, which will impact significantly synaptic current summation and the ability to fire high-frequency spike trains. These data suggest a novel role for dendrites in auditory brainstem neurons: the speeding of EPSPs for faster and more precise output signal transfer.Significance StatementAuditory circuits that compute sound localization express different types of specialized synapses. Some are capable of fast, precise and sustained synaptic transmission. As the paradigm example, principal cells of the MNTB receive a single calyx-type nerve terminal on their soma and this large excitatory synapse produces fast and brief supra-threshold EPSPs that can trigger trains of high frequency spikes. However, these neurons also extend thin and long dendrites with unknown function. We examined the relationship between dendritic morphology, passive electrical properties and EPSP waveform. We found that more mature neurons with intact dendrites have lower input resistances and short EPSP waveforms, ideally suited for conveying precise timing information, whereas immature neurons with shorter dendrites and higher input resistance have longer lasting EPSPs.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

Auditory Brainstem Responses in a Case of High-Frequency Conductive Hearing Loss

1985 ◽  
Vol 50 (4) ◽  
pp. 346-350 ◽  
Author(s):  
Michael P. Gorga ◽  
Jan K. Reiland ◽  
Kathryn A. Beauchaine
Keyword(s):  
Hearing Loss ◽  
High Frequency ◽  
Conductive Hearing Loss ◽  
Auditory Brainstem ◽  
Intensity Function ◽  
Auditory Brainstem Responses ◽  
Normal Limits ◽  
Interpeak Latency ◽  
Lower Limits ◽  
Conductive Hearing

Click-evoked auditory brainstem responses were measured in a patient with high-frequency conductive hearing loss. As is typical in cases of conductive hearing loss, Wave I latency was prolonged beyond normal limits. Interpeak latency differences were just below the lower limits of the normal range. The Wave V latency-intensity function, however was abnormally steep. This pattern is explained by the hypothesis that the slope of the latency-intensity function is determined principally by the configuration of the hearing loss. In cases of high-frequency hearing loss (regardless of the etiology), the response may be dominated by more apical regions of the cochlea at lower intensities and thus have a longer latency.

Enhanced Ih Depresses Rat Entopeduncular Nucleus Neuronal Activity From High-Frequency Stimulation or Raised Ke+

2008 ◽  
Vol 99 (5) ◽  
pp. 2203-2219 ◽  
Author(s):  
D. S. Shin ◽  
P. L. Carlen
Keyword(s):  
Neuronal Activity ◽  
High Frequency ◽  
Neurological Diseases ◽  
Input Resistance ◽  
High Frequency Stimulation ◽  
Channel Activity ◽  
Entopeduncular Nucleus ◽  
Inhibitory Effects ◽  
Frequency Stimulation ◽  
Spontaneous Action

High-frequency stimulation (HFS) is used to treat a variety of neurological diseases, yet its underlying therapeutic action is not fully elucidated. Previously, we reported that HFS-induced elevation in [K+]e or bath perfusion of raised Ke+ depressed rat entopeduncular nucleus (EP) neuronal activity via an enhancement of an ionic conductance leading to marked depolarization. Herein, we show that the hyperpolarization-activated ( Ih) channel mediates the HFS- or K+-induced depression of EP neuronal activity. The perfusion of an Ih channel inhibitor, 50 μM ZD7288 or 2 mM CsCl, increased input resistance by 23.5 ± 7% (ZD7288) or 35 ± 10% (CsCl), hyperpolarized cells by 3.4 ± 1.7 mV (ZD7288) or 2.3 ± 0.9 mV (CsCl), and decreased spontaneous action potential (AP) frequency by 51.5 ± 12.5% (ZD7288) or 80 ± 13.5% (CsCl). The Ih sag was absent with either treatment, suggesting a block of Ih channel activity. Inhibition of the Ih channel prior to HFS or 6 mM K+ perfusion not only prevented the previously observed decrease in AP frequency, but increased neuronal activity. Under voltage-clamp conditions, Ih currents were enhanced in the presence of 6 mM K+. Calcium is also involved in the depression of EP neuronal activity, since its removal during raised Ke+ application prevented this attenuation and blocked the Ih sag. We conclude that the enhancement of Ih channel activity initiates the HFS- and K+-induced depression of EP neuronal activity. This mechanism could underlie the inhibitory effects of HFS used in deep brain stimulation in output basal ganglia nuclei.

Voltage clamping single cells in intact Malpighian tubules of mosquitoes

2000 ◽  
Vol 279 (4) ◽  
pp. F747-F754 ◽  
Author(s):  
R. Masia ◽  
D. Aneshansley ◽  
W. Nagel ◽  
R. J. Nachman ◽  
K. W. Beyenbach
Keyword(s):  
Apical Membrane ◽  
Single Cells ◽  
Basolateral Membrane ◽  
Malpighian Tubule ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Malpighian Tubules ◽  
Shunt Resistance ◽  
Transport Pathways ◽  
Principal Cells

Principal cells of the Malpighian tubule of the yellow fever mosquito were studied with the methods of two-electrode voltage clamp (TEVC). Intracellular voltage ( V pc) was −86.7 mV, and input resistance ( R pc) was 388.5 kΩ ( n = 49 cells). In six cells, Ba2+ (15 mM) had negligible effects on V pc, but it increased R pc from 325.3 to 684.5 kΩ ( P< 0.001). In the presence of Ba2+, leucokinin-VIII (1 μM) increased V pc to −101.8 mV ( P < 0.001) and reduced R pc to 340.2 kΩ ( P < 0.002). Circuit analysis yields the following: basolateral membrane resistance, 652.0 kΩ; apical membrane resistance, 340.2 kΩ; shunt resistance ( R sh), 344.3 kΩ; transcellular resistance, 992.2 kΩ. The fractional resistance of the apical membrane (0.35) and the ratio of transcellular resistance and R sh (3.53) agree closely with values obtained by cable analysis in isolated perfused tubules and confirm the usefulness of TEVC methods in single principal cells of the intact Malpighian tubule. Dinitrophenol (0.1 mM) reversibly depolarized V pc from −94.3 to −10.7 mV ( P< 0.001) and reversibly increased R pc from 412 to 2,879 kΩ ( P < 0.001), effects that were duplicated by cyanide (0.3 mM). Significant effects of metabolic inhibition on voltage and resistance suggest a role of ATP in electrogenesis and the maintenance of conductive transport pathways.

Influence of the neuropeptide somatostatin on the development of dendritic morphology: a cysteamine-depletion study in the rat auditory brainstem

1997 ◽  
Vol 101 (1-2) ◽  
pp. 107-114 ◽  
Author(s):  
Martin Kungel ◽  
Kerstin Piechotta ◽  
Heike-Jana Rietzel ◽  
Eckhard Friauf
Keyword(s):  
Auditory Brainstem ◽  
Dendritic Morphology

scholarly journals Effect of changes in action potential shape on calcium currents and transmitter release in a calyx–type synapse of the rat auditory brainstem

1999 ◽  
Vol 354 (1381) ◽  
pp. 347-355 ◽  
Author(s):  
J. G. G. Borst ◽  
B. Sakmann
Keyword(s):  
Action Potential ◽  
Transmitter Release ◽  
Time Course ◽  
Calcium Influx ◽  
Auditory Brainstem ◽  
Calcium Currents ◽  
Medial Nucleus ◽  
Potential Shape ◽  
Presynaptic Calcium ◽  
Rat Brainstem

We studied the relation between the size of presynaptic calcium influx and transmitter release by making simultaneous voltage clamp recordings from presynaptic terminals, the calyces of Held and postsynaptic cells, the principal cells of the medial nucleus of the trapezoid body, in slices of the rat brainstem. Calyces were voltage clamped with different action potential waveforms. The amplitude of the excitatory postsynaptic currents depended supralinearly on the size of the calcium influx, in the absence of changes in the time–course of the calcium influx. This result is in agreement with the view thact at this synapse most vesicles are released by the combined action of multiple calcium channels.

Infrared/Video Eng Recording of Eye Movements to Evaluate the Inferior Vestibular Nerve Using the Minimal Caloric Test

1988 ◽  
Vol 98 (3) ◽  
pp. 207-210 ◽  
Author(s):  
Fred H. Linthicum ◽  
Ron Waldorf ◽  
William M. Luxford ◽  
Sharon Caltogirone
Keyword(s):  
High Frequency ◽  
Auditory Brainstem ◽  
Vestibular Nerve ◽  
Caloric Test ◽  
Nerve Section ◽  
High Frequency Hearing Loss ◽  
Vestibular Response ◽  
Infrared Video ◽  
Inferior Vestibular Nerve ◽  
Brainstem Response

The technique was originally developed to test the inferior vestibular nerve in tumor suspects whose high-frequency hearing loss exceeded the capabilities of the auditory brainstem response tests and whose electronystagmographic results showed no significantly reduced vestibular response. The test has subsequently been found effective to demonstrate persistent singular nerve fiber function in patients with persistent vertigo after retrolabyrinthine vestibular nerve section.

scholarly journals Effects of exposing gonadectomized and intact C57BL/6J mice to a high-frequency augmented acoustic environment: Auditory brainstem response thresholds and cytocochleograms

2006 ◽  
Vol 221 (1-2) ◽  
pp. 73-81 ◽  
Author(s):  
James F. Willott ◽  
Justine VandenBosche ◽  
Toru Shimizu ◽  
Da-Lian Ding ◽  
Richard Salvi
Keyword(s):  
Auditory Brainstem Response ◽  
High Frequency ◽  
Auditory Brainstem ◽  
Acoustic Environment ◽  
Brainstem Response ◽  
Response Thresholds ◽  
Augmented Acoustic Environment
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