Meeting Abstract

S1.9  Tuesday, Jan. 4  The role of genetically-defined lamina VIII interneurons in generating the mammalian locomotor rhythm. GOSGNACH, Simon; University of Alberta, Edmonton AB gosgnach@ualberta.ca

Locomotor activity in mammals is generated by neural networks known as central pattern generators (CPGs), which are comprised of spinal interneurons located in the lower thoracic and lumbar spinal cord. Recently, molecular genetic characterization of transcription factor expression at early embryonic time points has led to the identification of discrete interneuronal populations in the central nervous system. This work has provided valuable insight into the structure and mechanism of function of the locomotor CPG. Of particular interest is the V0 interneuronal population, which is located in lamina VIII of the postnatal spinal cord, the region in which the core elements of the locomotor CPG reside. This population is comprised of inhibitory and excitatory interneurons, and has been shown to play a role in coordinating left-right alternation during locomotion. Recently we have investigated whether the V0 cells are involved in locomotor rhythm generation. Whole cell patch clamp recordings from genetically-labelled V0 neurons in neonatal mice demonstrate that many of these cells fire rhythmically during fictive locomotion. Investigation of intrinsic membrane properties demonstrate that certain V0 cells display a persistent inward current as well as voltage-dependent modulation of oscillation frequency. Anatomical tracing experiments demonstrate that a subset of V0 cells receive synaptic contacts from locomotor command regions in the brainstem. Taken together, these results provide evidence that a subpopulation of the V0 potentially act as part of the rhythm-generating network of the locomotor CPG.