The goal of work in the Xu-Friedman lab is to understand how cells in the brain, called neurons, perform behaviorally useful computations. We focus on the connections between neurons, called synapses, and how they act under normal conditions, so that we can understand how synapses go wrong in disease, and what the consequences are for perception and behavior.
We study the auditory system, where sounds are captured by the ear and transformed into electrical signals by the inner ear. These electrical signals are carried by the auditory nerve to the brain. The auditory nerve enters the brain at the cochlear nucleus, where it forms synapses onto multiple types of neurons, each of which has its own role in perception.
View of the cochlear nucleus. The auditory nerve is labelled in green. Each axon enters the cochlear nucleus and forms two branches, one towards the anteroventral cochlear nucleus, and one towards the dorsal cochlear nucleus. The molecular layer of the dorsal cochlear nucleus is labelled in red. A general blue stain labels cell nuclei. Picture from Chanda et al. (2011).
We study the synapses in one part of the cochlear nucleus that are made onto bushy cells. These synapses are called “endbulbs of Held” after their discoverer, neuroanatomist Hans Held. The bushy cells specialize in analyzing information about the timing of sounds, which is used to determine where a sound is coming from.
You can find out more about our projects in the rest of the lab website.
Auditory nerve (green) forming an endbulb synapse (yellow) onto a bushy cell (red). Picture by T. Ngodup.