Marc D. Binder
University of Southern California, 1974
Office phone: (206) 543-2509
Google scholar citations
INPUT-OUTPUT FUNCTIONS OF MOTONEURONS
The discharge behavior of mammalian motoneurons is governed by a complex interplay between the excitatory and inhibitory synaptic inputs they receive and the cells' intrinsic electrical properties. Motoneurons express a host of active dendritic conductances that can dramatically alter the transmission of synaptic current to the soma and the integration of different synaptic input systems. We are presently investigating the dendritic mechanisms affecting the transfer of synaptic current to the soma of hypoglossal motoneurons recorded in rat brainstem slices. We study the voltge-dependance of the synaptic currents, what types of voltage-gated conductances on the dendrites affect the transfer of current to the soma and how concurrently-activated synaptic currents interact. We also use fluorescent imaging to determine the spatial distribution of the dendritic sodium, calcium, and mixed-cation channels. Our experimental projects are complemented by computer simulations using compartmental models of motoneurons with different types and distributions of dendritic conductances to help interpret the experimental data. Collectively, our experimental and simulation studies provide new information on the roles of dendritic conductances in motoneurons on the transfer of synaptic current to the soma, on the integration of their multiple synaptic inputs, and on how motoneurons transform synaptic inputs into frequency-modulated spike train outputs.