Auditory Neural Pathway Simulation

Abstract

We describe an effort to simulate the neural pathway from the inner ear (cochlea) to the primary auditory cortex in the brain. The human cochlea contains sensory cells (inner hair cells), which respond to the mechanical motion of traveling waves that sweep along the basilar membrane. Neurons triggered by the sensory cells carry sound signals from the cochlea to the brain through a series of a half-dozen transfer sites. At each junction, firing neurons stimulate some and inhibit other neighboring neurons. The signal processing effects of these interactions are not fully understood. The net behavior is difficult to observe in-vivo because the neurons are not easily accessible and only a relatively few can be measured at one time. As a result, the "neural code" that represents sound signals is not understood. We do know, however, that our perception of sound is much more refined than the signal observable at the cochlea. Frequencies are only broadly separated within the cochlea, for example, yet we are able to perceive very narrow differences in pitch. The simulation model we are constructing provides a means to fully instrument all of the neurons and their interactions. The model allows for a wide range of signal analysis experimentation, which we hope will help untangle how this neural processing works.