Medicine, Dentistry and Health SciencesDepartment of Otolaryngology

Ion Channel Activity in Auditory Neurons

Principal investigator

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Dr Karina Needham

Background

The activity of the auditory nerve in normal hearing depends upon both the electrical impulses generated by the hair cells in the cochlea, together with the composition of ion channels expressed in the primary afferent neurons (spiral ganglion neurons; SGNs). Ion channels are pore-forming proteins embedded in the plasma membrane of all excitable cells and are responsible for the selective passage of ions across the membrane. In this way, they provide the means to control and generate the electrical activity of the neuron and modulate its excitability.
In some forms of deafness the sensory hair cells no longer provide electrical input to the SGNs. In such cases the cochlear implant is used to electrically stimulate the SGNs directly. However, the efficacy of the cochlear implant in replicating sound perception is dependent upon the integrity of the SGNs following deafness. It is therefore important to understand how ion channel expression and activity in spiral ganglion neurons change in deafness, and with therapeutic intervention, such as neurotrophin treatment.

Research aims

  • To explore the changes in ion channel activity and expression that occurs in the auditory system with deafness and neurotrophin treatment.

Techniques

  • Patch-clamp electrophysiology
  • Immunohistochemistry

Staff

Collaborators

Funding

  • The Garnett Passe and Rodney Williams Memorial Foundation
  • The University of Melbourne, Early Career Researcher Grant Scheme

Publications

  • Matsuyama H., Nguyen T.V., Hunne B., Thacker M., Needham K., McHugh D. and Furness J.B. (2008) Evidence that TASK1 channels contribute to the background current in AH/Type II neurons of the guinea-pig intestine. Neuroscience 155: 738-750
  • Needham K. and Paolini A.G. (2007) The commissural pathway and cochlear nucleus bushy neurons: An in vivo intracellular investigation. Brain Research 1134: 113-121
  • Needham K. and Paolini A.G. (2006) Neural timing, inhibition and the nature of stellate cell interaction in the ventral cochlear nucleus. Hearing Research 216-217: 31-42
  • Needham K. (2006) The cochlear nucleus commissural pathway: an electrophysiological investigation. PhD. Department of Otolaryngology, The University of Melbourne
  • Paolini A.G., Clarey J.C., Needham K. and Clark G.M. (2005) Balanced inhibition and excitation underlies spike firing regularity in ventral cochlear nucleus chopper neurons. European Journal of Neuroscience 21: 1236-1248
  • Paolini A.G., Clarey J.C., Needham K. and Clark G.M. (2004) Fast inhibition alters first spike timing in auditory brainstem neurons. Journal of Neurophysiology 92: 2615-2621 (2004)
  • Needham K. and Paolini A.G. (2003) Fast inhibition underlies the transmission of auditory information between cochlear nuclei. Journal of Neuroscience 23: 6357-6361
  • Mulders W.H.A.M., Paolini A.G., Needham K. and Robertson D. (2003) Olivocochlear collaterals evoke excitatory effects in onset neurons of the rat cochlear nucleus. Hearing Research 176: 113-121

 

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