The long term goal of this project is to better understand the mechanisms of early olfactory coding in the mammalian brain, in particular to address questions about how odor-evoked activity from different populations of olfactory receptor neurons. Is integrated. Mitral and tufted (M/T) cells are the principle input and output neurons of the main olfactory bulb, a structure which is known to play an important role in the separation and identification of odors. M/T cells do not synapse on each other, but are connected by reciprocal dendroendritic synapses that they make with inhibitory granule cells. The granule cell-mediated maternal inhibition of mitral cells is thought to be an important mechanism for integrating patterns of odor-evoked activity. Long-ranger lateral inhibition requires the activation of distal regions of mitral cell dendrites, but little is known about the mechanisms underlying action potential propagation or transmitter release in these structures.
The aims of this project are to measure directly the propagation of activity in mitral cell maternal dendrites and to understand the mechanisms responsible for the activity dependence of propagation that has been observed. The role of synaptic input in regulating action potential propagation also will be examined in order to determine how the pattern of lateral inhibition exerted by an active mitral cell might be modified by the ongoing activity of other mitral cells in the bulb. The results of these experiments will provide insights into the neural basis of sensory coding and into how deficits sensory coding might arise from damage to this system.
