These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Effects on cochlear responses of activation of descending pathways from the inferior colliculus.
    Author: Mulders WH, Robertson D.
    Journal: Hear Res; 2000 Nov; 149(1-2):11-23. PubMed ID: 11033243.
    Abstract:
    The inferior colliculus (IC) has been shown anatomically to make direct descending connections with medial olivocochlear (MOC) neurones in the auditory brainstem. The MOC neurones project to the outer hair cells in the cochlea and inhibit cochlear neural output. This study investigated the effect of IC stimulation on cochlear output in both guinea pigs and rats in order to determine the functional significance of the IC-to-olivocochlear system projection. Stimulation of the central nucleus and the external cortex of the IC in paralysed guinea pigs, both contra- and ipsilaterally to the test cochlea, resulted in a small increase of the cochlear microphonic amplitude and a small decrease of the compound action potential (CAP) amplitude, the latter equivalent to a 3-6 dB change in acoustic input. Effects on the CAP were maximal in the frequency range 6-10 kHz. These effects were consistent with partial activation of the MOC system. In unparalysed rats, stimulation of the inferior colliculus evoked a large, prolonged suppression ranging from 5-12 dB in the amplitude of distortion product otoacoustic emissions (2f(1)-f(2); DPOAE), as reported previously by Scates et al. (1999). However, this suppression was decreased to only 0-3 dB when the animals were paralysed, suggesting that the larger suppression in the unparalysed state was the consequence of either a general masking effect caused by animal movement, or activation of middle ear muscles by the inferior colliculus stimulation. The results indicate a small but significant excitatory effect of the inferior colliculus on the medial olivocochlear system under conditions of anaesthesia and paralysis.
    [Abstract] [Full Text] [Related] [New Search]