View article

To survive, we must interact with an ever-changing world. Our capacity to move accurately in a range of environments lies in the brain’s ability to flexibly modify our motor behavior. For example, simply holding an object in the hand changes the arm’s dynamic environment. That is, the additional weight of the object changes the relationship between applied forces and motion such that the brain’s motor commands and muscle forces no longer result in the intended arm movement. In order to skillfully manipulate the object, the brain must alter its motor commands to compensate for the object’s weight and achieve a desired movement. Subsequent movements are improved with time and practice; this process is called motor learning. While many of our motor skills are acquired and refined through active physical practice, we can also learn how to make movements by observing others. This is referred to as observational …