Down-regulation of inhibition following unilateral deafening

Physiological and neurochemical experiments described here suggest that unilateral deafening causes a reduction in inhibition in the adult gerbil inferior colliculus (IC) contralateral to the deafened ear. Multiple-unit recordings were made from single electrode penetrations in the IC prior to and d...

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Bibliographic Details
Published in:Hearing research 2000-09, Vol.147 (1), p.183-187
Main Authors: Mossop, J.E., Wilson, M.J., Caspary, D.M., Moore, D.R.
Format: Article
Language:English
Subjects:
Animals
Auditory plasticity
Biological and medical sciences
Cochlea - physiopathology
Cochlear ablation
Deafness
Deafness - physiopathology
Down-Regulation
Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology
Evoked Potentials, Auditory
Gerbillinae
Glutamate Decarboxylase - metabolism
Inferior Colliculi - physiopathology
Inferior colliculus
Medical sciences
Neuronal Plasticity
Non tumoral diseases
Otorhinolaryngology. Stomatology
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Summary:Physiological and neurochemical experiments described here suggest that unilateral deafening causes a reduction in inhibition in the adult gerbil inferior colliculus (IC) contralateral to the deafened ear. Multiple-unit recordings were made from single electrode penetrations in the IC prior to and directly after contralateral cochlear ablation. These recordings showed up to 60% increases in the proportion of sampled loci at which neural activity excited by ipsilateral stimulation was observed after the ablation. Novel excitatory responses were evident within minutes of the ablation. Western blotting for glutamic acid decarboxylase protein levels showed significant decreases in the IC contralateral to cochlear ablation, relative to those in the ipsilateral IC, at 24 h and 7 days survival after the ablation. Four hour or 1 year survival post-ablation did not produce significant contralateral/ipsilateral differences in relation to the control group. Taken together, these results suggest the presence of at least two, short-term mechanisms involved in the central response to cochlear removal, both of which appear to implicate a decreased inhibitory influence. One is a very rapid, stimulus-related, functional unmasking. The other is a more delayed reduction in the capacity of γ-aminobutyric acid synthesis in the IC.
ISSN:0378-5955
1878-5891
DOI:10.1016/S0378-5955(00)00054-X