Cortical control of movement is mediated by wide-spread projections impacting many nervous system regions in a top-down manner. Although much knowledge about cortical circuitry has been accumulated from local cortical microcircuits, cortico-cortical and cortico-subcortical networks, how cortex communicates to regions closer to motor execution, including the brainstem, is less well understood.
In this dissertation, we investigate the organization of cortico-medulla projections and their roles in controlling forelimb movement. We focus on anatomical and functional relationships between cortex and lateral rostral medulla (LatRM), a region in caudal brainstem which is shown to be key in the control of forelimb movement. Our findings reveal the precise anatomical and functional organization between different cortical regions and matched postsynaptic neurons in the caudal brainstem, tuned to different phases of one carefully orchestrated behavior, which advance the our knowledge on circuit mechanisms involved in the control of body movements, and unravel the logic of how the top-level control region in the mammalian nervous system – the cortex – intersects with a high degree of specificity with command centers in the brainstem and beyond
