Wiener-Kernel Analysis of Responses to Noise of Chinchilla Auditory-Nerve Fibers

Abstract

Responses to broadband Gaussian white noise were recorded in auditory-nerve fibers of deeply anesthetized chinchillas and analyzed by computation of zeroth-, first-, and second-order Wiener kernels. The first-order kernels (similar to reverse correlations or "revcors") of fibers with characteristic frequency (CF) <2 kHz consisted of lightly damped transient oscillations with frequency equal to CF. Because of the decay of phase locking strength as a function of frequency, the signal-to-noise ratio of first-order kernels of fibers with CFs >2 kHz decreased with increasing CF at a rate of about -18 dB per octave. However, residual first-order kernels could be detected in fibers with CF as high as 12 kHz. Second-order kernels, 2-dimensional matrices, reveal prominent periodicity at the CF frequency, regardless of CF. Thus onset delays, frequency glides, and near-CF group delays could be estimated for auditory-nerve fibers innervating the entire length of the chinchilla cochlea.

Reverse Correlation Analysis of Auditory-Nerve Fiber Responses to Broadband Noise in a Bird, the Barn Owl

“…2B). At first glance, impulse responses looked similar to what has been reported in the past (de Boer and de Jongh 1978;Carney and Yin 1988;Recio-Spinoso et al 2005;Fischer et al 2011;Fontaine et al 2013): They consisted of a high-frequency oscillation (at around the best frequency of the neuron) modulated in time by an envelope that rose and decayed in a few milliseconds. We fitted analytical functions called gamma chirps to the portion of the STAs where the envelope was higher than 5 % of the maximum, as previously reported (Wagner et al 2009;Fischer et al 2011;Fontaine et al 2013).…”

“…To compare IF slopes independently of frequency, we expressed them in unitless values (Recio et al 1998;Shera 2001;Recio-Spinoso et al 2005). To do so, the slope was divided by BF 2 .…”

“…These invasive techniques are potentially very harmful for the vulnerable cochlea. Therefore, re-sponses at the auditory nerve continue to serve as an access point to cochlear mechanisms (van der Heijden and Joris 2003;Recio-Spinoso et al 2005;Temchin et al 2011;Versteegh et al 2011). Barn owl auditory nerve responses have been studied with tones (Köppl 1997a, b).…”

“…However, the highly nonlinear character of auditory transduction restricts the characterization of cochlear mechanics using pure-tone stimulation. Experiments presenting broadband stimuli have been extensively performed in the mammalian auditory system (e.g., de Boer and de Jongh 1978;Carney and Yin 1988;van der Heijden and Joris 2003;Recio-Spinoso et al 2005;Versteegh et al 2011) as they are thought to linearize the system for a fixed input level (Recio-Spinoso et al 2009). …”

“…Using linear filters, we studied the relationship between properties of the transfer functions like phase modulation, sharpness of frequency tuning, and response delays, which can be informative about the underlying cochlear mechanisms (Tan and Carney 2003;van der Heijden and Joris 2003;Recio-Spinoso et al 2005;Temchin et al 2011;Versteegh et al 2011). Where possible, we compared the owl's AN transfer function features to published data in mammals.…”