D. A. Borton
School of Engineering and the Brown Institute for Brain Science, Brown University, Providence,, RI, 02912, USA
The human nervous system is arguably the most advanced information-processing network in existence. Multiarea, recurrent networks in our brains enable flexible behavior in a dynamic and uncertain world. Amazingly, small-scale networks of the spinal cord can regulate intelligent responses on a millisecond timescale to a poorly placed foot on a stair, initiating an ever-useful correction loop and avoiding catastrophe. Large-scale networks across vast landscapes of the brain regulate everything from the decision to take a step forward to knowing when to take a step backward.
In the healthy nervous system, the development of intention and motor execution is a dynamic and highly distributed process that originates in the brain. The intended action is transmitted along the axon super highway of the spinal cord and down to smart circuits in the spinal cord that transform the descending command into coordinated patterns of muscle activation. A continuous stream of sensory and motor information is actively coalesced in the brain to ensure the accurate and sequenced execution of movement. The output of the motor cortex and brainstem motor regions is under the continuous influence of other structures of the brain, including the cerebellum and basal ganglia, which are essential for producing smooth movements. ...