Neurotransmitter phenotypes of descending systems in the rat lumbar spinal cord

Sensorimotor processes within the spinal cord are profoundly influenced by descending systems from the brain yet the neurotransmitter phenotypes of these systems remains enigmatic. Using tract tracing methods, this study identifies the neurochemical content of axons descending from the sensorimotor cortex and sites within the anatomically diverse reticular formation. There are several classes of neurons in spinal lumbar segments targeted by these descending systems which contribute to recruiting adaptively appropriate motor patterns. This study investigates the neuronal targets of descending systems and the neurochemical content of their inputs. Immunofluorescent tissue containing labelled neuronal processes were examined and reconstructed interneurons were defined according to their neuronal geometry and morphology across laminar boundaries