Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cochlear Nucleus”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2000

Deafferentation-induced changes in protein kinase C expression in the rat cochlear nucleus.

Isoforms of the signal transducing molecule, protein kinase C (PKC), may play a role in neural plasticity following sensory deafferentation. To explore the role of PKC in central auditory plasticity, we studied the effect of auditory deafferentation on the expression of PKC betaI, betaII, gamma, and delta in the rat dorsal (DCN) and ventral cochlear nucleus (VCN), using immunocytochemistry. Male rats were treated with kanamycin and furosemide to induce hair cell loss. At various intervals post-treatment, brains were perfusion-fixed and processed for immunocytochemistry. Following deafferentation, we observed a gradual increase in PKC betaI immunoreactivity (ir) in the deepest layers of the DCN, possibly representing synapses of primary afferents or parallel fibers on unlabeled neurons. Correlated with this, we observed an increase in the number of neurons in the deep DCN that showed PKC delta ir. In controls, we observed PKC gamma ir in small ovoid cells concentrated in the middle layer of the DCN. From days 4 through 14 after deafferentation, we found an increase in the intensity of staining of these cells, with a return toward control levels by day 28. Finally, Purkinje-like cells (PLC) in the VCN, which express only PKC delta in control rats, began to express PKC gamma after deafferentation, correlated with increased expression of calbindin D28k in PLC. Thus PKC isoforms are differentially regulated in the CN following deafferentation, supporting a role for PKC in auditory plasticity.

Animals↗
PubMed1996

Responses of ventral cochlear nucleus units in the chinchilla to amplitude modulation by low-frequency, two-tone complexes.

For a tone that is amplitude modulated by two tones (fmod1 and fmod2), neither the stimulus waveform nor the half-wave rectified waveform has spectral energy at the envelope beat frequency (fmod2-fmod1). The response of ventral cochlear nucleus units in the chinchilla were recorded for best frequency tones that were amplitude modulated by low-frequency, two-tone complexes. Fourier analysis of poststimulus time histograms shows spectral peaks at fmod2-fmod1 in addition to the peaks at fmod1 and fmod2. The peaks in the neural spectra arise from compressive nonlinearities in the auditory system. The magnitudes of these spectral peaks are measures of synchrony at each frequency component. For all units, synchrony at fmod1 and fmod2 is greater than the synchrony at fmod2-fmod1. For a given unit, synchrony at fmod1 and fmod2 remains relatively constant as a function of overall level, whereas synchrony at fmod2-fmod1 decreases as the level increases. Synchrony was quantified in terms of the Rayleigh statistic (z), which is a measure of the statistical significance of the phase locking. In terms of z, phase locking at fmod1 and fmod2 is largest in chopper units, whereas onset-chopper units and primarylike units having sloping saturation in their rate-level functions show the smallest amount of phase locking. Phase locking at fmod2-fmod1 is also largest in chopper units, and smallest in onset-chopper units and primarylike units with sloping saturation.

Acoustic Stimulation↗
PubMed1999

Vesicular acetylcholine transporter in the rat cochlear nucleus: an immunohistochemical study.

After being synthesized in the cytoplasm of axon terminals, acetylcholine is packaged into synaptic vesicles by a proton-dependent transporter, vesicular acetylcholine transporter (VAChT). Localization of VAChT is restricted to cholinergic neurons, especially their terminals. We used an anti-VAChT antibody from INCSTAR to localize cholinergic terminals in the rat cochlear nucleus (CN), an important brainstem auditory center. VAChT immunoreactivity in the rat CN appears as labeled puncta and a few connecting fibers. In ventral CN (VCN), VAChT-labeled puncta are closely associated with somatic profiles of medium to large neurons. In and near the granular regions of VCN, VAChT-labeled puncta are more diffusely scattered. In the subpeduncular corner and the medial sheet, some VAChT-labeled fibers are seen in connection with especially prominent VAChT-labeled puncta. In dorsal CN (DCN), VAChT-labeled puncta show no clear association with somata and are found in all layers. Ultrastructurally, VAChT labeling is seen in the cytoplasm and is associated with synaptic vesicle membrane of terminals with small round vesicles. Such VAChT-labeled terminals synapse with cell bodies and dendrites in the CN.(J Histochem Cytochem 47:83-90, 1998)

Acetylcholine↗
PubMed2005

Intrinsic oscillations in spike trains indicate non-renewal statistics due to convergence of inputs in dorsal cochlear nucleus neurons.

The occurrence of intrinsic oscillations (IOs) in a unit's discharge is reflected by a prominent peak in the power spectrum (i.e., Fourier transform of the autocorrelation function) of spike trains obtained from single-unit discharge, at a frequency independent of stimulus spectral characteristics. IOs have been reported by researchers in the dorsal cochlear nucleus (DCN) of both the cat and the Mongolian gerbil. It has been hypothesized that IOs are related to inter-spike interval (ISI) regularity (e.g., [Hear. Res. 58 (1992) 153]). This hypothesis is tested in this paper. Responses to multiple presentations of 50-300 ms duration tone bursts, at and near the unit's best frequency (BF) at 20-60 dB re threshold were recorded from DCN units of barbiturate-anesthetized (30 units), as well as decerebrate (53 units) Mongolian gerbils. IOs in the recordings were then compared with the IOs in simulations of spiking-neuron models. The models were selected because: (1) their ISI regularity characteristics follow those of experimental data and (2) their IO properties are completely determined by their ISI regularity. Such comparison reveals that Ghoshal's hypothesis fails for a fraction of the units. These results suggest a re-evaluation of the purported relationship between IOs, ISI regularity, and SAM response. Alternate hypotheses are proposed here using computational models that are based on convergence of multiple neural inputs onto the unit under study. These models produce non-renewal statistics that resemble those of the experimental data, as is evident from IO-based analysis.

Action Potentials↗
PubMed1997

Responses of chopper units in the ventral cochlear nucleus of the anaesthetised guinea pig to clicks-in-noise and click trains.

Auditory brainstem responses (ABRs) have been measured with clicks, clicks masked by noise, click trains and pseudorandom maximum length sequences (MLS) of clicks. To investigate the neuronal populations contributing to the ABR under these stimulation conditions, we measured the extracellular responses of ventral cochlear nucleus (VCN) units in the urethane-anaesthetised guinea pig. We studied 23 chopper, 7 primary-like and 7 onset units. This report focuses on the responses from chopper units. The probability of discharge for chopper units increased with increasing click level reaching nearly 100% in many units, over a range of about 20-30 dB. Following each response to a click there was a 5-10 ms suppression of the spontaneous or noise evoked activity. As the level of the noise was increased over a range of 20-30 dB, the response to the clicks gradually decreased leading to a complete abolition of the click response at high noise levels. In a few units, low level noise produced a facilitation of the response to single clicks. In response to constant level equally spaced click trains, discharge probability increased with increasing minimum pulse interval (MPI), approaching 100% for MPIs of 4-8 ms in some units. The recovery afforded by the gaps in the MLS train often resulted in higher discharge probability for MLS than click trains with the same MPI, while response probabilities for MLS and click trains were similar when compared at equivalent average click rates. At short MPIs (0.5 and 1.0 ms), peri stimulus time histograms in response to click trains resembled those to best frequency (BF) tones and noisebursts, with chopping peaks unrelated to unit BF. VCN units show highly synchronised and reliable responses to click trains, MLS trains and clicks masked by noise. The decrease in discharge rate and increase in latency of chopper units with decreasing click level, increasing click rate and increasing masker level parallel the peak amplitude and latency changes observed in the auditory brainstem response.

Acoustic Stimulation↗
PubMed2001

Modulation of P-CREB and expression of c-fos in cochlear nucleus and superior olive following electrical intracochlear stimulation.

Investigating activity-dependent plasticity in the auditory brain stem of the adult rat, we observed that electrical intracochlear stimulation led to a tonotopically localized modulation of the phosphorylation of the cAMP response element binding protein (CREB) and an equally localized expression of the immediate early gene product c-Fos in cochlear nucleus and superior olive. As P-CREB is thought to act as transcription factor on one promoter site of the c-fos gene, we compared immunolabeling for P-CREB and c-fos in adjacent brain sections. Following 2h sustained stimulation in previously deafened animals, labelling for P-CREB declined in regions where c-Fos labelling increased. This suggests that the level or state of P-CREB (e.g. whether it is phosphorylated or not) are affected by intracochlear stimulation in a process that appears to be linked to the stimulation-dependent expression of c-Fos in auditory brain stem nuclei.

Animals↗
PubMed1989

Vasopressin excites neurones located in the dorsal cochlear nucleus of the guinea-pig brainstem.

The effect of arginine vasopressin (AVP) on neurones in the dorsal cochlear nucleus (DCN) of young guinea-pigs of either sex was investigated in brainstem slices. Most impaled neurones fired in a regular manner, either spontaneously or following a depolarizing current injection. AVP, at concentrations of 10-1000 nM, excited 19/19 neurones from male and 16/19 neurones from female animals. This effect of AVP was concentration-dependent and could be mimicked by the V1 agonist [Phe2,Orn8]VT. Oxytocin was less potent than AVP and a selective V2 agonist, deamino-DAVP, was without effect. Thus, a class of DCN neurones is probably endowed with functional V1 vasopressin receptors. By making use of an antibody raised against the vasopressin-related glycopeptide, dense AVP-like immunoreactivity was found in the DCN of young animals of either sex.

Action Potentials↗
PubMed1988

Induction of aberrant functional afferents to the chick cochlear nucleus.

Surgical extirpation of the otocyst on embryonic day (E) 3 in chick embryos prevents formation of the cochlear nerve and results in development of an aberrant axonal projection from the contralateral cochlear nucleus (nucleus magnocellularis, NM) to the deafferented NM. We have studied the morphology of this projection using horseradish peroxidase injections in NM axons and light and electron microscopy. The ability of the projection to activate its target neurons synaptically was assessed by means of extracellular microelectrode recording from in vitro preparations of the chick brainstem. The aberrant projection arises as a vertically directed branch from the contralaterally traveling NM axon at the medial border of nucleus laminaris (NL). This axonal branch forms boutonal endings that may terminate anywhere in NM but are most common in its ventral and medial regions. In our experiments, this projection is not seen on the unoperated side of experimental animals or in normal controls from E11 onward but is found on the operated sides of all experimental animals, including those with bilateral removal of the otocysts. The aberrant projection persists at least from E11 through hatching and has essentially identical features in unilaterally and bilaterally lesioned animals. The endings of the aberrant projection are boutonal in form and, in the electron microscope, exhibit all of the elements associated with normal synapses. Electrophysiological studies confirm that stimulation of the aberrant axons can elicit postsynaptic responses in NM and suggest that these synapses use an excitatory amino acid neurotransmitter.

Animals↗
PubMed1983

Tuning characteristics of cochlear nucleus units in response to electrical stimulation of the cochlea.

The responses of single units in the ventral cochlear nucleus of acute anesthetized guinea pigs were studied with continuous sinusoidal electrical stimuli presented through a multi-electrode implant in the scala tympani. Implants had two or four electrodes along the axis of the scala with 1 mm separations. Best frequencies were consistently in the 100 Hz range (50-250 Hz) with thresholds of about 0.063 mA peak-to-peak. Tuning curves were usually symmetrical with slopes of 3-4 dB/octave, both below and above the best frequency. The relative sharpness of the tuning curves, as measured by Q10dB, averaged 0.2. Dynamic ranges as determined by the intensity-rate functions for the various frequencies were 2-15 dB. No significant difference was found between tuning characteristics of units in response to stimulation via the apical or basal pair of implant electrodes. The findings suggest some limitations on the applicability of independent stimulating channels in multi-electrode implants.

Acoustic Stimulation↗
PubMed1993

Convergence of auditory nerve fibers onto bushy cells in the ventral cochlear nucleus: implications of a computational model.

1. Convergence of auditory nerve (AN) fibers onto bushy cells of the ventral cochlear nucleus (VCN) was investigated with a model that describes the electrical membrane properties of these cells. The model consists of a single compartment, representing the soma, and includes three voltage-sensitive ion channels (fast sodium, delayed-rectifier-like potassium, and low-threshold potassium). These three channels have characteristics derived from voltage clamp data of VCN bushy cells. The model also contains a leakage channel, membrane capacitance, and synaptic inputs. The model accurately reproduces the membrane rectification seen in current clamp studies of bushy cells, as well as their unique current clamp responses. 2. In this study, the number and synaptic strength of excitatory AN inputs to the model were varied to investigate the relationship between input convergence parameters and response characteristics. From 1 to 20 excitatory synaptic inputs were applied through channels in parallel with the voltage-gated channels. Each synapse was driven by an independent AN spike train; spike arrivals produced brief (approximately 0.5 ms) conductance increases. The number (NS) and conductance (AE) of these inputs were systematically varied. The input spike trains were generated as a renewal point process that accurately models characteristics of AN fibers (refractoriness, adaptation, onset latency, irregularity of discharge, and phase locking). Adaptation characteristics of both high and low spontaneous rate (SR) AN fibers were simulated. 3. As NS and AE vary over the ranges 1-20 and 3-80 nS, respectively, the full range of response types seen in VCN bushy cells are produced by the model, with AN inputs typical of high-SR AN fibers. These include primarylike (PL), primarylike-with-notch (Pri-N), and onset-L (On-L). In addition, Onset responses, whose association with bushy cells in uncertain, and "dip" responses, which are not seen in the VCN, are produced. Dip responses occur with large NS and/or AE, and are due to depolarization block. When the AN inputs have the adaptation characteristics of low-SR AN fibers, PL--but not Pri-N or On-L responses--are produced. This suggests that neurons showing Pri-N and On-L responses must receive high-SR AN inputs. 4. The regularity of discharge of the model is compared with that of VCN bushy cells, using a measure derived from the mean and standard deviation of interspike intervals. Regularity is an important constraint on the model because the regularity of VCN bushy cells is the same as that of their AN inputs.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Regularity and latency of units in ventral cochlear nucleus: implications for unit classification and generation of response properties.

1. The responses of neurons in the ventral cochlear nucleus (VCN) of decerebrate cats are described with regard to their regularity of discharge and latency. Regularity is measured by estimating the mean and standard deviation of interspike intervals as a function of time during responses to short tone bursts (25 ms). This method extends the usual interspike-interval analysis based on interval histograms by allowing the study of temporal changes in regularity during transient responses. The coefficient of variation (CV), equal to the ratio of standard deviation to mean interspike interval, is used as a measure of irregularity. Latency is measured as the mean and standard deviation of the latency of the first spike in response to short tone bursts, with 1.6-ms rise times. 2. The regularity and latency properties of the usual PST histogram response types are shown. Five major PST response type classes are used: chopper, primary-like, onset, onset-C, and unusual. The presence of a prepotential in a unit's action potentials is also noted; a prepotential implies that the unit is recorded from a bushy cell. 3. Units with chopper PST histograms give the most regular discharge. Three varieties of choppers are found. Chop-S units (regular choppers) have CVs less than 0.35 that are approximately constant during the response; chop-S units show no adaptation of instantaneous rate, as measured by the inverse of the mean interspike interval. Chop-T units have CVs greater than 0.35, show an increase in irregularity during the response and show substantial rate adaptation. Chop-U units have CVs greater than 0.35, show a decrease in irregularity during the response, and show a variety of rate adaptation behaviors, including negative adaptation (an increase in rate during a short-tone response). Irregular choppers (chop-T and chop-U units) rarely have CVs greater than 0.5. Choppers have the longest latencies of VCN units; all three groups have mean latencies at least 1 ms longer than the shortest auditory nerve (AN) fiber mean latencies. 4. Chopper units are recorded from stellate cells in VCN (35, 42). Our results for chopper units suggest a model for stellate cells in which a regularly firing action potential generator is driven by the summation of the AN inputs to the cell, where the summation is low-pass filtered by the membrane capacitance of the cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1995

Processing of modulation frequency in the dorsal cochlear nucleus of the guinea pig: amplitude modulated tones.

The modulation frequency (Fm), particularly high Fm (> 200 Hz), in amplitude modulated (AM) tones can elicit the perception of the periodicity pitch (Langner, 1992). In this study, single unit responses to the Fms of the sinusoidal AM tones were investigated at 50 to 90 dB SPL. The recordings were made from the dorsal cochlear nucleus (DCN) of neuroleptic anesthetized guinea pigs with an intact cerebellum. The DCN units show a good capability of phase-locking to Fm at 400-1200 Hz. On-S-type II and Pauser/Buildup (P/B) units have a high modulation gain (7.2-8.3 dB). P/B units can preserve the high modulation gain (5-9 dB) up to 90 dB SPL. The modulation gain exponentially increases with decreasing modulation depth (Dm) and the phase-locking is detectable even at the Dm as low as 2-5%. The 'central skipping' of the phase-locking peak has been found at deep Dms in a few cases. The synchronization is independent of the discharge rate and can remain high even when the responses to AM tones are inhibited below the spontaneous activity. Such encoding behaviors over the unit's response area show that the Fm phase-locking is strong near or at its characteristic frequency (CF). The synchronization index (SI) versus carrier frequency (Fc) curve is similar to the inverse shape of tuning curve but more narrowly tuned than the iso-intensity function of pure tones at moderate to high intensity levels. The phase-locking is related to the unit's spontaneous rate (SR). The average modulation gain of the lower SR (< or = 2 spikes/s) units is 5 dB higher than that of the higher SR (> 2 spikes/s) units (8.16 and 2.92 dB, respectively) at 70 dB SPL. These results suggest that AM information is temporally encoded over broad ranges of modulation parameters in the DCN and is conveyed by the Fc channel. Such a timing mechanism can play an important role in processing of complex sounds under normal acoustic conditions.

Acoustic Stimulation↗
PubMed1993

Projections of physiologically characterized spherical bushy cell axons from the cochlear nucleus of the cat: evidence for delay lines to the medial superior olive.

Bushy cells in the anteroventral cochlear nucleus (AVCN) receive their principal excitatory input from the auditory nerve and are the primary source of excitatory input to more centrally located brainstem auditory nuclei. Despite this pivotal position in the auditory pathway, details of the basic physiological information being carried by axons of these cells and their projections to more central auditory nuclei have not been fully explored. In an attempt to clarify these details, we have physiologically characterized and anatomically labeled individual axons of the spherical bushy cell (SBC) class of the cat AVCN. The characteristic frequencies (CFs) of our injected SBC population are low, all less than 12 kHz and primarily (83%) less than 3 kHz, while their spontaneous activity is comparatively high (mean of 59 spikes/sec). In response to short tone bursts at CF, low CF (< 1 kHz) SBC units can phase-lock better than auditory nerve fibers. SBCs with CFs above 1 kHz have primary-like responses at all stimulus levels and can show robust phase-locking to an off-CF, 500 Hz tone. When compared with our previously reported population of labeled globular bushy cells (GBC; Smith et al., 1991, J. Comp. Neurol. 304:387-407), some similarities and differences are apparent in both physiological response properties and axonal projection pattern. GBCs show no low frequency bias in CFs, have lower spontaneous rates, and the high CF units exhibit a primary-like-with-notch response at high stimulus levels as a consequence of a very well timed onset component. Low CF, GBC short tone responses are indistinguishable from those of SBCs. Anatomically, the axons of SBCs cross the midline in the dorsal component of the trapezoid body and typically innervate the medial superior olive (MSO) on both sides, the ipsilateral lateral superior olive (LSO), and the contralateral ventral nucleus of the lateral lemniscus (VNLL). The projections to the contralateral, but not the ipsilateral MSO, show a rostral to caudal delay line configuration, similar to the scheme first proposed by Jeffress (1948, J. Comp. Psychol. 41:35-39). The form of this delay line is consistent with the topographic map of interaural time delays reported by Yin and Chan (1990, J. Neurophysiol. 64:465-488). Projections to the ipsilateral LSO often take an indirect route. In contrast, GBC axons travel in the ventral component of the trapezoid body, never innervate the MSO, rarely innervate the ipsilateral LSO, and always innervate the contralateral medial nucleus of the trapezoid body. The terminal specializations of both SBC and GBC axons contain round vesicles.

Animals↗
PubMed1992

Effects of OFF-BF tones on responses of chopper units in ventral cochlear nucleus. I. Regularity and temporal adaptation patterns.

1. We have recorded the responses of neurons in the anteroventral cochlear nucleus (AVCN) of barbiturate-anesthetized cats to pure tones [either at the unit's best frequency (BF) or at another frequency (OFF-BF)] and to two-tone combination stimuli. 2. The effects of OFF-BF input (either alone or presented simultaneously with a BF tone in a two-tone stimulus) on the response patterns of choppers may include not only rate inhibition but changes in the discharge regularity and the temporal adaptation properties of the spike trains. 3. In the majority of cases we studied (119 of 146 frequencies examined in 45 units), the discharge regularity of a response to an OFF-BF or two-tone stimulus is comparable with that of a "rate-matched" BF tone response. In a minority of cases (27 of 146 frequencies examined), however, OFF-BF input (either alone or in a two-tone stimulus format) changed the regularity compared with that of a rate-matched BF tone response. 4. In the majority of cases studied (139 of 171 frequencies examined in 53 units), the initial pattern of rate adaptation ["temporal adaptation pattern" (TAP)] was the same in response to a short tone burst at BF, to an OFF-BF tone burst, or to a pair of tones. The TAP can, however, be significantly altered by OFF-BF input, although this is a comparatively infrequent occurrence in our data sample (32 of 171 frequencies examined), from the response to BF tone to the response to the two-tone or OFF-BF stimulus, are as follows: sustained to slowly adapting; slowly adapting to transiently adapting, and transiently adapting to slowly adapting. Changes in the TAPs of chopper unit responses have been recorded from both regular and irregular choppers and cannot be accounted for on the basis of changes in sustained firing rate. These changes in the discharge regularity and TAP in the small minority of cases suggest that (at least in these cases) the inhibitory effect of OFF-BF input is not simply the result of two-tone suppression at the level of the auditory nerve fiber input. 5. We have observed that regular choppers may be transformed into irregular choppers by OFF-BF (rate inhibitory) input.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1999

[Morphometric development and the variability of neurons of the human auditory system: ventral cochlear nucleus and superior medial olivary nucleus].

The development of the human ventral cochlear and medial superior olivary nuclei was studied. We made serial sections of the brain in 10 fetuses at 16-40 weeks of gestation (WG), an infant at 2 months of age and an adult of 63 years using an electronic planimeter with a computer. Although the shape of neurons of the two nuclei was different, our morphometric analysis showed that the development of both of them accelerates between 18 and 21 WG in terms of the columnar length and volume, neuronal size and circularity ratio and the amount of Nissl bodies increases gradually.

Cochlear Nucleus↗
PubMed1989

Threshold functions for electrical stimulation of the human cochlear nucleus.

Thresholds to sinusoidal and biphasic pulsatile electrical stimuli were measured in two patients with electrodes positioned on the cochlear nucleus. The threshold functions differ from those observed in patients with scala tympani electrodes, primarily at low sinusoidal frequencies and long pulse widths. This difference is probably due to differences in the biophysical properties of the stimulated neural tissues in the two regions.

Auditory Threshold↗
PubMed2005

Ameliorative effects of exposing DBA/2J mice to an augmented acoustic environment on histological changes in the cochlea and anteroventral cochlear nucleus.

DBA/2J (D2) mice, which exhibit very early progressive sensorineural hearing loss, were treated nightly with an augmented acoustic environment (AAE) initiated before the onset of hearing, and consisting of repetitive bursts of a 70-dB sound pressure level (SPL), 4-25 kHz noise band. At 55 days of age, AAE-treated mice exhibited less elevation of auditory brainstem response thresholds, fewer missing hair cells, and greatly reduced loss of anteroventral cochlear nucleus (AVCN) volume and neuron number compared to untreated control mice. It was hypothesized that the central neuroprotective effect was associated with increased afferent input to AVCN neurons evoked by the AAE as well as a healthier cochlea.

Acoustic Stimulation↗
PubMed1979

A new type of synapse in the ventral cochlear nucleus.

In this paper we report the appearance of flat vesicle-containing endings in aldehyde-fixed ventral cochlear nucleus of rats with qualitative and quantitative properties suggesting they should be identified as calyceal processes. Their synaptic vesicles are elongate and significantly smaller than the vesicles in the calyces of Lenn and Reese (1966). Therefore these endings are flat vesicular calyceal processes, possibly of inhibitory function.

Animals↗