title: Lateral superior olive function in congenital deafness.
abstract: The development of cochlear implants for the treatment of patients with profound hearing loss has advanced considerably in the last few decades, particularly in the field of speech comprehension. However, attempts to provide not only sound decoding but also spatial hearing are limited by our understanding of circuit adaptations in the absence of auditory input. Here we investigate the lateral superior olive (LSO), a nucleus involved in interaural level difference (ILD) processing in the auditory brainstem using a mouse model of congenital deafness (the dn/dn mouse). An electrophysiological investigation of principal neurons of the LSO from the dn/dn mouse reveals a higher than normal proportion of single spiking (SS) neurons, and an increase in the hyperpolarisation-activated I(h) current. However, inhibitory glycinergic input to the LSO appears to develop normally both pre and postsynaptically in dn/dn mice despite the absence of auditory nerve activity. In combination with previous electrophysiological findings from the dn/dn mouse, we also compile a simple Hodgkin and Huxley circuit model in order to investigate possible computational deficits in ILD processing resulting from congenital hearing loss. We find that the predominance of SS neurons in the dn/dn LSO may compensate for upstream modifications and help to maintain a functioning ILD circuit in the dn/dn mouse. This could have clinical repercussions on the development of stimulation paradigms for spatial hearing with cochlear implants.
authors.affiliation: Division of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra ACT, Australia.
authors.forename: Kiri
authors.initials: K
authors.lastname: Couchman
authors.forename: Andrew
authors.initials: A
authors.lastname: Garrett
authors.forename: Adam S
authors.initials: AS
authors.lastname: Deardorff
authors.forename: Frank
authors.initials: F
authors.lastname: Rattay
authors.forename: Susanne
authors.initials: S
authors.lastname: Resatz
authors.forename: Robert
authors.initials: R
authors.lastname: Fyffe
authors.forename: Bruce
authors.initials: B
authors.lastname: Walmsley
authors.forename: Richardson N
authors.initials: RN
authors.lastname: Leão
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000378:metabolism / Q000503:physiopathology*; D001307:Auditory Perception; D002352:Carrier Proteins / Q000378:metabolism; D003056:Cochlear Nerve / Q000503:physiopathology; D003638:Deafness / Q000151:congenital / Q000378:metabolism / Q000503:physiopathology* / Q000523:psychology; D004195:Disease Models, Animal; D004558:Electric Stimulation; D016057:Evoked Potentials, Auditory, Brain Stem; D019706:Excitatory Postsynaptic Potentials; D005973:Glutamine / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008959:Models, Neurological; D009154:Mutation; D009433:Neural Inhibition; D009847:Olivary Nucleus / Q000378:metabolism / Q000503:physiopathology*; D018408:Patch-Clamp Techniques; D013997:Time Factors
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C514628:TMC1 protein, mouse; C073441:gephyrin; D005973:Glutamine; D005998:Glycine