New insights into the organization of sensorimotor circuits in the spinal cord

Martyn Goulding
Molecular Neurobiology Laboratory, Systems Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, USA

Recent studies have defined many of the key developmental pathways that control the specification, organization and functional properties of interneurons in the spinal cord. We have taken advantage of these developmental insights to functionally dissect the how sensorimotor circuits in the spinal cord are organized and address the contribution that molecularly identified neuronal populations make to the circuits that control movement in mammals. Our studies demonstrate how a combination of genetic, anatomical, physiological and behavioral approaches can be used to map functional circuits in the spinal cord. These studies include efforts to map the connectivity, neurotransmitter phenotype and cellular properties of V0, V1, V2 and V3 interneurons and determine the contribution that each of these ventral interneuron populations make to locomotor behaviors. We find that each ventral interneuron class controls a distinct facet of motor behavior, suggesting that the core circuitry for locomotion is largely modular in nature. More recently, research in that lab has begun to address the central pathways that transmit and gate cutaneous sensory inputs to the spinal cord. These studies reveal the presence of defined circuits in the dorsal horn that transduce a discrete range of sensory modalities such as light touch and mechanical pain.