Motor program

A motor program is an abstract metaphor of the central organization of movement and control of the many degrees of freedom involved in performing an action. Biologically realistic alternatives to the metaphor of the "motor program" are represented by central pattern generators.^[1]p. 182 Signals transmitted through efferent and afferent pathways allow the central nervous system to anticipate, plan or guide movement. Evidence for the concept of motor programs include the following:^[1]p. 182

1. Processing of afferent information (feedback) is too slow for on-going regulation of rapid movements.
2. Reaction time (time between “go” signal and movement initiation) increases with movement complexity, suggesting that movements are planned in advance.

1. Movement is possible even without feedback from the moving limb. Moreover, velocity and acceleration of feedforward movements such as reaching are highly proportional to the distance of the target.
2. The existence of motor equivalence, i.e., the ability to perform the same action in multiple ways for instance using different muscles or the same muscles under different conditions. This suggests that a general code specifying the final output exists which is translated into specific muscle action sequences
3. Brain activation precedes that of movement. For example, the supplementary motor area becomes active one second before voluntary movement.

This is not meant to underestimate the importance of feedback information, merely that another level of control beyond feedback is used:^[1]

1. Before the movement as information about initial position, or perhaps to tune the spinal apparatus.
2. During the movement, when it is either “monitored” for the presence of error or used directly in the modulation of movements reflexively.
3. After the movement to determine the success of the response and contribute to motor learning.