Preferred intervals in the spontaneous activity of primary auditory neurons

1979 ◽  
Vol 66 (11) ◽  
pp. 582-584 ◽  
Author(s):  
G. A. Manley
2020 ◽  
Author(s):  
Travis A. Babola ◽  
Sally Li ◽  
Zhirong Wang ◽  
Calvin Kersbergen ◽  
Ana Belén Elgoyhen ◽  
...  

ABSTRACTSpontaneous bursts of electrical activity in the developing auditory system arise within the cochlea prior to hearing onset and propagate through future sound processing circuits of the brain to promote maturation of auditory neurons. Studies in isolated cochleae revealed that this intrinsically generated activity is initiated by ATP release from inner supporting cells (ISCs), resulting in activation of purinergic autoreceptors, K+ efflux and subsequent depolarization of inner hair cells (IHCs). However, little is known about when this activity emerges or whether different mechanisms underlie distinct stages of development. Here we show that spontaneous electrical activity in mouse cochlea emerges within ISCs during the late embryonic period, preceding the onset of spontaneous correlated activity in IHCs and spiral ganglion neurons (SGNs), which begins at birth and follows a base to apex developmental gradient. At all developmental stages, pharmacological inhibition of P2Y1 metabotropic purinergic receptors dramatically reduced spontaneous activity in these three cell types. Moreover, in vivo imaging within the inferior colliculus of awake mice revealed that auditory neurons within future isofrequency zones exhibit coordinated neural activity at birth. The frequency of these discrete bursts increased progressively during the postnatal prehearing period, yet remained dependent on P2RY1. Analysis of mice with disrupted cholinergic signaling in the cochlea, indicate that this input modulates, rather than initiates, spontaneous activity before hearing onset. Thus, the auditory system uses a consistent mechanism involving ATP release from ISCs and activation of purinergic autoreceptors to elicit coordinated excitation of neurons that will process similar frequencies of sound.SIGNIFICANCE STATEMENTIn developing sensory systems, groups of neurons that will process information from similar sensory space exhibit highly correlated electrical activity that is critical for proper maturation and circuit refinement. Defining the period when this activity is present, the mechanisms responsible and the features of this activity are crucial for understanding how spontaneous activity influences circuit development. We show that, from birth to hearing onset, the auditory system relies on a consistent mechanism to elicit correlate firing of neurons that will process similar frequencies of sound. Targeted disruption of this activity will increase our understanding of how these early circuits mature and may provide insight into processes responsible for developmental disorders of the auditory system.


2010 ◽  
Vol 22 (7) ◽  
pp. 1675-1697 ◽  
Author(s):  
Zbyněk Pawlas ◽  
Lev B. Klebanov ◽  
Viktor Beneš ◽  
Michaela Prokešová ◽  
Jiří Popelář ◽  
...  

A new statistical method for the estimation of the response latency is proposed. When spontaneous discharge is present, the first spike after the stimulus application may be caused by either the stimulus itself, or it may appear due to the prevailing spontaneous activity. Therefore, an appropriate method to deduce the response latency from the time to the first spike after the stimulus is needed. We develop a nonparametric estimator of the response latency based on repeated stimulations. A simulation study is provided to show how the estimator behaves with an increasing number of observations and for different rates of spontaneous and evoked spikes. Our nonparametric approach requires very few assumptions. For comparison, we also consider a parametric model. The proposed probabilistic model can be used for both single and parallel neuronal spike trains. In the case of simultaneously recorded spike trains in several neurons, the estimators of joint distribution and correlations of response latencies are also introduced. Real data from inferior colliculus auditory neurons obtained from a multielectrode probe are studied to demonstrate the statistical estimators of response latencies and their correlations in space.


Author(s):  
Xin-Lu Yin ◽  
Hui-Qun Jie ◽  
Min Liang ◽  
Li-Na Gong ◽  
Han-Wei Liu ◽  
...  

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
M. W. Nishani Dayaratne ◽  
Srdjan M. Vlajkovic ◽  
Janusz Lipski ◽  
Peter R. Thorne

Prior to the “onset of hearing,” developing cochlear inner hair cells (IHCs) and primary auditory neurons undergo experience-independent activity, which is thought to be important in retaining and refining neural connections in the absence of sound. One of the major hypotheses regarding the origin of such activity involves a group of columnar epithelial supporting cells forming Kölliker’s organ, which is only present during this critical period of auditory development. There is strong evidence for a purinergic signalling mechanism underlying such activity. ATP released through connexin hemichannels may activate P2 purinergic receptors in both Kölliker’s organ and the adjacent IHCs, leading to generation of electrical activity throughout the auditory system. However, recent work has suggested an alternative origin, by demonstrating the ability of IHCs to generate this spontaneous activity without activation by ATP. Regardless, developmental abnormalities of Kölliker’s organ may lead to congenital hearing loss, considering that mutations in ion channels (hemichannels, gap junctions, and calcium channels) involved in Kölliker’s organ activity share strong links with such types of deafness.


2000 ◽  
Vol 83 (3) ◽  
pp. 1452-1468 ◽  
Author(s):  
Timothy A. Jones ◽  
Sherri M. Jones

Statoacoustic ganglion cells in the mature bird include neurons that are responsive to sound (auditory) and those that are not (nonauditory). Those that are nonauditory have been shown to innervate an otolith organ, the macula lagena, whereas auditory neurons innervate the basilar papilla. In the present study, single-unit recordings of statoacoustic ganglion cells were made in embryonic (E19, mean = 19.2 days of incubation) and hatchling (P6–P14, mean = 8.6 days posthatch) chickens. Spontaneous activity from the two age groups was compared with developmental changes. Activity was evaluated for 47 auditory, 11 nonauditory, and 6 undefined eighth nerve neurons in embryos and 29 auditory, 26 nonauditory, and 1 undefined neurons in hatchlings. For auditory neurons, spontaneous activity displayed an irregular pattern [discharge interval coefficient of variation (CV) was >0.5, mean CV for embryos was 1.46 ± 0.58 and for hatchlings was 1.02 ± 0.25; means ± SD]. Embryonic discharge rates ranged from 0.05 to 97.6 spikes per second (sp/s) for all neurons (mean 18.6 ± 16.9 sp/s). Hatchling spontaneous rates ranged from 1.2 to 185.2 sp/s (mean 66.5 ± 39.6 sp/s). Discharge rates were significantly higher for hatchlings ( P < 0.001). Many embryonic auditory neurons displayed long silent periods between irregular bursts of neural activity, a feature not seen posthatch. All regular bursting discharge patterns were correlated with heart rate in both embryos and hatchlings. Preferred intervals were visible in the time interval histograms (TIHs) of only one embryonic neuron in contrast to 55% of the neurons in posthatch animals. Generally, the embryonic auditory TIH displayed a modified quasi-Poisson distribution. Nonauditory units generally displayed regular (CV <0.5) or irregular (CV >0.5) activity and Gaussian and modified-Gaussian TIHs. Long silent periods or bursting patterns were not a characteristic of embryonic nonauditory neurons. CV varied systematically as a function of discharge rate in nonauditory but not auditory primary afferents. Minimum spike intervals (dead time) and interval modes for auditory neurons were longer in embryos (dead time: embryos 2.88 ± 6.85 ms; hatchlings 1.50 ± 1.76 ms; modal intervals: embryo 10.09 ± 22.50 ms, hatchling 3.54 ± 3.29 ms). The results show that significant developmental changes occur in spontaneous activity between E19 and posthatch. It is likely that both presynaptic and postsynaptic changes in the neuroepithelium contribute to maturational refinements during this period of development.


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