Faculté des sciences

Direct comparison between properties of adaptation of the auditory nerve and the ventral cochlear nucleus in response to repetitive clicks

Meyer, Kaspar ; Rouiller, Eric M. ; Loquet, Gérard

In: Hearing Research, 2007, vol. 228, no. 1-2, p. 144-155

The present study was designed to complete two previous reports [Loquet, G., Rouiller, E.M., 2002. Neural adaptation to pulsatile acoustical stimulation in the cochlear nucleus of the rat. Hear. Res. 171, 72–81; Loquet, G., Meyer, K., Rouiller, E.M., 2003. Effects of intensity of repetitive acoustic stimuli on neural adaptation in the ventral cochlear nucleus of the rat. Exp. Brain Res. 153,... More

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    Summary
    The present study was designed to complete two previous reports [Loquet, G., Rouiller, E.M., 2002. Neural adaptation to pulsatile acoustical stimulation in the cochlear nucleus of the rat. Hear. Res. 171, 72–81; Loquet, G., Meyer, K., Rouiller, E.M., 2003. Effects of intensity of repetitive acoustic stimuli on neural adaptation in the ventral cochlear nucleus of the rat. Exp. Brain Res. 153, 436–442] on neural adaptation properties in the auditory system of the rat. Again, auditory near-field evoked potentials (ANEPs) were recorded in response to 250-ms trains of clicks from an electrode chronically implanted in the ventral cochlear nucleus (VCN). Up to now, our interest had focused on the adaptive behavior of the first one (N₁) of the two negative ANEP components. A re-examination of our data for the second negative component (N₂) was now undertaken. Results show that the adaptation time course observed for N₂ displayed the same three-stage pattern previously reported for N₁. Similarly, adaptation became more pronounced and occurred faster as stimulus intensity and/or repetition rate were increased. Based on latency data which suggest N₁ and N₂ to be mainly due to the activity of auditory-nerve (AN) fibers and cochlear nucleus neurons, respectively, it was concluded that neural adaptation assessed by gross-potentials was similar in the AN and VCN. This finding is meaningful in the context of our search to restore normal adaptation phenomena via electro-auditory hearing with an auditory brainstem implant on the same lines as our work in cochlear implants.