scholarly journals Multidimensional stimulus encoding in the auditory nerve of the barn owl

2018 ◽  
Vol 144 (4) ◽  
pp. 2116-2127
Author(s):  
Brian J. Fischer ◽  
Jacob L. Wydick ◽  
Christine Köppl ◽  
José L. Peña
Keyword(s):  
Auditory Nerve ◽  
Barn Owl ◽  
Multidimensional Stimulus

Frequency Tuning and Spontaneous Activity in the Auditory Nerve and Cochlear Nucleus Magnocellularis of the Barn Owl Tyto alba

1997 ◽  
Vol 77 (1) ◽  
pp. 364-377 ◽  
Author(s):  
Christine Köppl
Keyword(s):  
Response Latency ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Frequency Tuning ◽  
Barn Owl ◽  
Nerve Fibers ◽  
Spontaneous Discharge ◽  
Tyto Alba ◽  
Nucleus Magnocellularis ◽  
Auditory Nerve Fibers

Köppl, Christine. Frequency tuning and spontaneous activity in the auditory nerve and cochlear nucleus magnocellularis of the barn owl Tyto alba. J. Neurophysiol. 77: 364–377, 1997. Single-unit recordings were obtained from the brain stem of the barn owl at the level of entrance of the auditory nerve. Auditory nerve and nucleus magnocellularis units were distinguished by physiological criteria, with the use of the response latency to clicks, the spontaneous discharge rate, and the pattern of characteristic frequencies encountered along an electrode track. The response latency to click stimulation decreased in a logarithmic fashion with increasing characteristic frequency for both auditory nerve and nucleus magnocellularis units. The average difference between these populations was 0.4–0.55 ms. The most sensitive thresholds were ∼0 dB SPL and varied little between 0.5 and 9 kHz. Frequency-threshold curves showed the simple V shape that is typical for birds, with no indication of a low-frequency tail. Frequency selectivity increased in a gradual, power-law fashion with increasing characteristic frequency. There was no reflection of the unusual and greatly expanded mapping of higher frequencies on the basilar papilla of the owl. This observation is contrary to the equal-distance hypothesis that relates frequency selectivity to the spatial respresentation in the cochlea. On the basis of spontaneous rates and/or sensitivity there was no evidence for distinct subpopulations of auditory nerve fibers, such as the well-known type I afferent response classes in mammals. On the whole, barn owl auditory nerve physiology conformed entirely to the typical patterns seen in other bird species. The only exception was a remarkably small spread of thresholds at any one frequency, this being only 10–15 dB in individual owls. Average spontaneous rate was 72.2 spikes/s in the auditory nerve and 219.4 spikes/s for nucleus magnocellularis. This large difference, together with the known properties of endbulb-of-Held synapses, suggests a convergence of ∼2–4 auditory nerve fibers onto one nucleus magnocellularis neuron. Some auditory nerve fibers as well as nucleus magnocellularis units showed a quasiperiodic spontaneous discharge with preferred intervals in the time-interval histogram. This phenomenon was observed at frequencies as high as 4.7 kHz.

Spontaneous Activity of Auditory Nerve Fibers in the Barn Owl (Tyto alba): Analyses of Interspike Interval Distributions

2009 ◽  
Vol 101 (6) ◽  
pp. 3169-3191 ◽  
Author(s):  
Heinrich Neubauer ◽  
Christine Köppl ◽  
Peter Heil
Keyword(s):  
Spontaneous Activity ◽  
Auditory Nerve ◽  
Interspike Interval ◽  
Barn Owl ◽  
Nerve Fibers ◽  
Temporal Coding ◽  
Tyto Alba ◽  
Ribbon Synapses ◽  
Auditory Systems ◽  
The Mean

In vertebrate auditory systems, the conversion from graded receptor potentials across the hair-cell membrane into stochastic spike trains of the auditory nerve (AN) fibers is performed by ribbon synapses. The statistics underlying this process constrain auditory coding but are not precisely known. Here, we examine the distributions of interspike intervals (ISIs) from spontaneous activity of AN fibers of the barn owl ( Tyto alba), a nocturnal avian predator whose auditory system is specialized for precise temporal coding. The spontaneous activity of AN fibers, with the exception of those showing preferred intervals, is commonly thought to result from excitatory events generated by a homogeneous Poisson point process, which lead to spikes unless the fiber is refractory. We show that the ISI distributions in the owl are better explained as resulting from the action of a brief refractory period (∼0.5 ms) on excitatory events generated by a homogeneous stochastic process where the distribution of interevent intervals is a mixture of an exponential and a gamma distribution with shape factor 2, both with the same scaling parameter. The same model was previously shown to apply to AN fibers in the cat. However, the mean proportions of exponentially versus gamma-distributed intervals in the mixture were different for cat and owl. Furthermore, those proportions were constant across fibers in the cat, whereas they covaried with mean spontaneous rate and with characteristic frequency in the owl. We hypothesize that in birds, unlike in mammals, more than one ribbon may provide excitation to most fibers, accounting for the different proportions, and that variation in the number of ribbons may underlie the variation in the proportions.

Prey groups in the pellets of the barn owl Tyto alba (Scopoli) in the Nigerian savanna

2001 ◽  
Vol 39 (1) ◽  
pp. 38-44 ◽  
Author(s):  
L. M. Lekunze ◽  
A. U. Ezealor ◽  
T. Aken'ova
Keyword(s):  
Barn Owl ◽  
Tyto Alba ◽  
Nigerian Savanna
Sign in / Sign up

Export Citation Format

Share Document