Motor programs
An excellent review article is:
Morris, M.E., Summers, J.J., Matyas, T.A., Iansek, R. (1994). Current status of the motor program. Physical Therapy, 74, 738-752.
Commentaries on this article also appear in Physical Therapy:
August 1994; 74(8):748-52.
December 1994; 74(12):1138, 1140.
The authors summarize evidence for existence of a motor program
- Deafferented subjects can move.
- Once in progress, rapid movements cannot be modified by sensory information.
- Anticipatory control in balance and reaching tasks appears stereotypic and preprogrammed.
- EMG patterns don’t change in experiments where limb movement is blocked.
- Reaction time is longer for complex movements than for simple movements.
- Central pattern generators have been defined, for instance, in the spinal cords of some animals.
They also summarize serious challenges to the motor program construct:
- Sensory feedback does refine details of movement.
- Location and space for storage of motor programs is unclear.
- Programs cannot allow for variability or novelty.
- Control system may be distributed, with no consistent "commander" to issue motor commands.
- Programs cannot respond to environmental and biomechanical constraints.