Mark Ospeck, PhD Physics, Brandeis Univ.
Research involves the study of neurons and hair cells (the sensory cells we use for
hearing) including the spiral ganglion neuron (SGN). The first neuron in our ascending
auditory pathway, the SGN connects an inner hair cell, which has converted a sound
wave into an electrical signal, to our cochlear nucleus.
It's well known that the SGN performs a rate-encoding of the sound intensity within
a frequency band, typically varying from 20 to 250 spikes/second, depending on the
loudness of the tone. At the present, though, the cell is thought to simply relay
and rate-encode an already amplified signal from the cochlear amplifier out in the
hair cells. However, the neuron contains an unusual H current which I hypothesize
is turned on by efferent feedback from the brain. When it's on, I believe that the
neuron will become unstable and oscillate. In this state, it should amplify synaptic
input from a hair cell that's within a narrow frequency band around its spontaneous
oscillation frequency. Essentially, I'm investigating whether the SGN can be turned
on as a lock-in amplifier.
For more information, please contact Dr. Mark Ospeck at email@example.com or 901.678.1668.
Above: Dr. Mark Ospeck working in the University of Memphis Integrated Microscopy Center