A characterisation of last order interneurons of the rodent spinal cord with specific focus on their roles in the control of locomotor activity

Walking is initiated by relatively simple “start” signals which are relayed from the brain to the spinal cord. Networks of neurons in the spinal cord are then responsible for controlling the complex pattern of muscle contractions which allow us to walk. The identities of the neurons in the spinal cord which control movement and the connections they form with each other are, however, poorly understood. We have long known that a major type of spinal neuron, called the motor neuron, sends signals directly to muscles to make them contract. Work performed as part of this project has described a new type of spinal neuron that connects to motor neurons to control the strength of the signals that motor neurons send to muscles. Importantly, this connection allows the strength of muscle contractions to be adjusted to allow us to move in different ways or in different environments. It is hoped that by turning up the “volume dial” formed by this new class of neurons it will be possible to stimulate motor neurons to send stronger signals to muscles to overcome the loss of movement associated with injury and disease.