Upper-limb impairment after stroke is caused by weakness, loss of individual joint control,
spasticity and abnormal synergies. Upper limb movement frequently involves abnormal,
stereotyped and fixed synergies, likely related to the increased use of subcortical networks
following the stroke. The flexible coordination of the shoulder and elbow joints is also
disrupted. New methods for motor learning, based on the stimulation of activity-dependent
neural plasticity have been developed. These include robots that can adaptively assist …