Motor control has been assigned to neural circuits located within the spinal cord. At the core of the spinal motor system are sets of local interneurons (INs) that are webbed in neuronal circuits capable of controlling the activity and output of spinal motor neurons.
Interneurons differ from each other by their type of afferent input, cell body positioning along the body axis, axonal trajectory and their axonal targets. The differentiation of INs is determined initially by gradients of morphogens distributed along the ventral/dorsal and the rostral/caudal axes. Morphogen concentration is interpreted by activation of expression of transcription factors. Each IN expresses a defined set of transcription factors (transcriptional code) that subsequently determine its axonal trajectories and target selection. A specific axonal pathway of a neuron, governed by a transcriptional code, is manifested by the expression of receptors for guidance molecules that discern the guidance cues en route and at their putative target.
Studies in our lab are aimed toward decoding the wiring of spinal neuronal circuits and understanding the role of interneurons in motor control. Specifically: defining the axonal trajectories of spinal IN and their neuronal circuit; elucidating the transcriptional code that governs the axonal patterning of INs; determining the role of guidance molecules at axonal choice points; characterizing neuronal receptors for positional guidance cues that control axonal choice along the dorsal/ventral, rostral/caudal and ipsi/contra-lateral axes; and ascertaining the role of defined IN population in simple motor behaviors.