Neural coding of pitch in the lateral lemniscus.

We are interested in how the activity of neurons in the brain leads to perception of sound. This project will unravel the neuronal basis for the perception we call "pitch". That is, the sensation which allows us to order sounds on a musical scale from "low" to "high". Pitch is not a physical acoustic parameter, it is a percept derived in the brain. Pitch allows us to segregate sounds of interest from background sounds. It forms the basis of melody in music, and prosody in speech. The brain's ability to code pitch affords animals a survival advantage: the chirps of predators, prey and mates usually evoke a strong pitch, whereas interfering background noises do not. From a human health perspective, understanding the neuronal basis of pitch is important for improving the design of hearing aids and implantable auditory prostheses. We will record activity from neurons in the brainstem of cats and chinchillas in a pathway known as the lateral lemniscus. This part of the auditory system is specialized for coding fine-timing information. Human behavioral evidence suggests this pathway is involved in pitch processing, but to-date this has not been explored from a neuronal coding perspective. Much previous work has focused on timing information as a potential code for pitch in other auditory brain regions. Our work will fill a significant gap in understanding precisely how this timing information is used in the brain to represent the acoustic parameters we perceive as pitch.