Meniere's Disease Research Laboratory
Lab head: Daniel Brown
Location: The Brain & Mind Research Institute
This laboratory researches the cause of Meniere's Disease, a hearing and balance disorder characterized by random attacks of severe vertigo and fluctuating hearing loss.
It is currently thought that an abnormal volume of fluid in the inner ear called "endolymphatic hydrops" that can be seen in MRI scans causes a displacement of the inner ear hair cells that sense sound and orientation.
We are investigating the effects of endolymphatic hydrops, with the ultimate goal of understanding the mechanisms that lead to its production so that a cure can be developed.
Research approach equipment: In vivo electrophysiological studies in guinea pigs are used to investigate the effects of abnormal fluid volumes on inner ear function. These studies include conventional measurements of extracellular hair cell and neural electrical and mechanical responses to sound from the cochlea, as well as the development of novel measurement techniques for assessing vestibular hair cell responses to head rotations and displacements. The aim is to obtain simultaneous measurements of cochlear and vestibular hair cell displacement and function during various experimental manipulations that mimick Meniere's Disease.
Patuzzi, R.B., Brown, D.J., McMahon, C.M., Halliday, A.F. Determinants of the spectrum of the neural electrical activity at the round window: transmitter release and neural depolarisation. Hear Res. 2004.190(1-2): 87-108. PMID: 15051132
McMahon, C.M., Brown, D.J., Patuzzi, R.B. Transient focal cooling at the round window and cochlear nucleus shows round window CAP originates from cochlear neurones alone. Hear Res. 2004. 190(1-2): 75-6. PMID: 15051131
Brown, D.J., McMahon, C.M., Patuzzi, R.B. K+ currents produce P1 in the RW CAP: evidence from DC current bias, K+ channel blockade and recordings from cochlea and brainstem. Hear Res. 2004. 190(1-2): 60-74. PMID: 15051130
Brown DJ, Hartsock JJ, Gill RM, Fitzgerald HE, Salt AN. 2009. Estimating the operating point of the cochlear transducer using low-frequency biased distortion products. J Acoust Soc Am. 125(4):2129-45. PMID: 19354389
Salt AN, Brown DJ, Hartsock JJ, Plontke SK. 2009. Displacements of the organ of Corti by gel injections into the cochlear apex. Hear Res. 250(1-2):63-75. PMID: 19217935
Brown, D.J., Patuzzi R.B. 2010. Evidence that the compound action potential (CAP) from the auditory nerve is a stationary potential generated across dura mater. Hear Res. 2010 Apr 26. [ahead of print] PMID: 20430085
Functional Role of Valves in the Membranous Labyrinth in the Inner Ear
Primary supervisor: Daniel Brown
Meniere’s Disease is a hearing and balance disorder that afflicts approximately 50,000 Australians. It is characterised by fluctuating hearing loss, tinnitus, fullness in the ear, and severe attacks of vertigo. The hallmark of Meniere’s is a bloating of the fluid-filled membranous labyrinth in the ear, which houses the mechanically sensitive cochlear and vestibular hair cells. Our resent research has focused on the function of a tissue duct in the membranous labyrinth that separates the vestibular system from the cochlea. This duct appears to function as a fluid valve (it’s called the ‘Valve of Bast’), temporarily opening when cochlear pressure increases, squirting fluid into the vestibular system and causing a transient loss of balance sensitivity. To investigate the symptoms of Meniere’s, and the function of the various inner ear valves, we perform a variety of physiological experiments such as injecting artificial endolymph with biomarkers into anaesthetised guinea pigs, whilst monitoring in vivo electrophysiological responses from the cochlea and vestibular system. We also image inner ears post-mortem and reconstruct in 3D using techniques such as Micro-CT or using our custom-built Light Sheet Fluorescent Microscope.
Co-supervisors: William Ryder, Ian Curthoys
Keywords: Otolaryngology, Physiology, Ear & hearing diseases