Abstract
Cochlear root neurons (CRNs) provide short-latency acoustic inputs to the caudal pontine reticular nucleus that elicit an acoustic startle reflex (ASR). Auditory prepulse inhibition (PPI) of the acoustic startle response is the reduction in ASR magnitude that is observed when a strong acoustic startling stimulus (pulse) is shortly preceded by a weak sound (prepulse). It has been suggested that a short descending auditory pathway conveys auditory prepulses to the level of the CRNs to mediate the inhibition of ASR. However, no electrophysiological data is available to confirm such inhibition. We here investigated the effects of auditory prepulses on the neuronal activity of CRNs using extracellular recordings in vivo from single CRNs. Our results show that CRN responses are strongly inhibited by auditory prepulses. As occurs in the behavioral paradigm, the inhibition of the CRN responses depended on parameters of the auditory prepulse, such as intensity and interstimulus interval, showing their strongest inhibition at high intensity level and short interstimulus intervals. Furthermore, we tested the auditory PPI on the activity of different neuron types in the ventral cochlear nucleus. Of all neuron types tested, only CRNs exhibited a strong attenuation of activity. Our results corroborate our previous hypothesis that CRNs might be involved in the neural circuit of the inhibition of the ASR and suggest that several neuronal pathways participate in that circuit.
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Acknowledgements
The authors thank #BFU2007-65210 and JCyL #GR221 to D.E.L; DC00341 from NIDCD to D.G.S.
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Gómez-Nieto, R., Horta-Júnior, J.A.C., Castellano, O., Sinex, D.G., López, D.E. (2010). Auditory Prepulse Inhibition of Neuronal Activity in the Rat Cochlear Root Nucleus. In: Lopez-Poveda, E., Palmer, A., Meddis, R. (eds) The Neurophysiological Bases of Auditory Perception. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-5686-6_8
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DOI: https://doi.org/10.1007/978-1-4419-5686-6_8
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