the MacLeod lab

Research topics

How do the synaptic properties of the auditory nerve terminals onto its targets in the cochlear nucleus affect transmission of acoustic information?

We use in vitro electrophysiological recordings from brain stem slices to ask detailed questions about the synaptic properties of auditory nerve inputs. Experiments using direct eelctrical stimulation of the nerve fibers, pharmacology, neuronal fills, combined with computational models of the synaptic transmission allow us to interrogate the information processing and filtering capabilities. We have found evidence for target dependent synaptic properties that contribute to divergent information processing along ascending pathways.

What intrinsic properties define the diverse target neuronal populations in the cochlear nucleus and how do these affect integration of auditory inputs?

The cochlear nucleus is a heterogeneous population of neurons with a range of firing properties that define their operating mode, from coincidence detectors to integrators. We are interested in the biophysical properties that define operating mode, especially with respect to encoding temporal features of sound, such as sound envelope, an important component of acoustic communication.

How do cell-specific adaptation mechanisms influence coding of sound intensity in vivo?

Adaptive cellular processes such as short-term synaptic plasticity (activity-dependent alterations in synaptic weight), intrinsic firing rate adaptation (via ion channel inactivation or hyperpolarizing currents), and modulatory transmitter feedback via second messenger systems are all candidate mechanisms for implementing intensity-related adaptation.

How are natural and artificially-evoked auditory nerve activity integrated in the cochlear nucleus?

In collaboration with cochlear implant researchers on campus, we are interested in how direct nerve stimulation by cochlear implant technology is interpreted by the brain. Cochlear implants are a highly successful prosthetic device that allows profoundly deaf subjects to hear speech and other environmental sounds, but how these signals are received and processed is still poorly understood.