PMID- 17670993
OWN - NLM
STAT- MEDLINE
DCOM- 20070828
LR  - 20231013
IS  - 1529-2401 (Electronic)
IS  - 0270-6474 (Print)
IS  - 0270-6474 (Linking)
VI  - 27
IP  - 31
DP  - 2007 Aug 1
TI  - Spontaneous activity of auditory-nerve fibers: insights into stochastic processes 
      at ribbon synapses.
PG  - 8457-74
AB  - In several sensory systems, the conversion of the representation of stimuli from 
      graded membrane potentials into stochastic spike trains is performed by ribbon 
      synapses. In the mammalian auditory system, the spiking characteristics of the 
      vast majority of primary afferent auditory-nerve (AN) fibers are determined 
      primarily by a single ribbon synapse in a single inner hair cell (IHC), and thus 
      provide a unique window into the operation of the synapse. Here, we examine the 
      distributions of interspike intervals (ISIs) of cat AN fibers under conditions 
      when the IHC membrane potential can be considered constant and the processes 
      generating AN fiber activity can be considered stationary, namely in the absence 
      of auditory stimulation. Such spontaneous activity is commonly thought to result 
      from an excitatory Poisson point process modified by the refractory properties of 
      the fiber, but here we show that this cannot be the case. Rather, the ISI 
      distributions are one to two orders of magnitude better and very accurately 
      described as a result of a homogeneous stochastic process of excitation 
      (transmitter release events) in which the distribution of interevent times is a 
      mixture of an exponential and a gamma distribution with shape factor 2, both with 
      the same scale parameter. Whereas the scale parameter varies across fibers, the 
      proportions of exponentially and gamma distributed intervals in the mixture, and 
      the refractory properties, can be considered constant. This suggests that all of 
      the ribbon synapses operate in a similar manner, possibly just at different 
      rates. Our findings also constitute an essential step toward a better 
      understanding of the spike-train representation of time-varying stimuli initiated 
      at this synapse, and thus of the fundamentals of temporal coding in the auditory 
      pathway.
FAU - Heil, Peter
AU  - Heil P
AD  - Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany. 
      peter.heil@ifn-magdeburg.de
FAU - Neubauer, Heinrich
AU  - Neubauer H
FAU - Irvine, Dexter R F
AU  - Irvine DR
FAU - Brown, Mel
AU  - Brown M
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neurosci
JT  - The Journal of neuroscience : the official journal of the Society for 
      Neuroscience
JID - 8102140
SB  - IM
MH  - Acoustic Stimulation/methods
MH  - Action Potentials/*physiology
MH  - Animals
MH  - Cats
MH  - Cochlear Nerve/*physiology
MH  - Female
MH  - Male
MH  - Nerve Fibers/*physiology
MH  - Stochastic Processes
MH  - Synapses/*physiology
PMC - PMC6673073
EDAT- 2007/08/03 09:00
MHDA- 2007/08/29 09:00
PMCR- 2008/02/01
CRDT- 2007/08/03 09:00
PHST- 2007/08/03 09:00 [pubmed]
PHST- 2007/08/29 09:00 [medline]
PHST- 2007/08/03 09:00 [entrez]
PHST- 2008/02/01 00:00 [pmc-release]
AID - 27/31/8457 [pii]
AID - 3251495 [pii]
AID - 10.1523/JNEUROSCI.1512-07.2007 [doi]
PST - ppublish
SO  - J Neurosci. 2007 Aug 1;27(31):8457-74. doi: 10.1523/JNEUROSCI.1512-07.2007.