From reflex to skill: the training of coordination.

All motor activity is based on inherent reflexes and on modification of those reflexes by higher centers. The reflex patterns are developed as the result of the neuronal connections and remain consistent rather than showing variability. It is only the extent of spread of excitation through the entire distribution of the reflex pathway that changes with intensity of stimulation byt the reflex pathway remains constant. Control of reflex activity by the pyramidal system precedes and is the basis for the development of the automatic engrams of coordination. However, precise control can be exerted through the pyramidal system only when the patient is related, the effort is low, and attention is directed to the single activity being attempted. An engram is formed only by repetition of the precise pattern of that engram. In the repetition of a precise pattern the inhibition of muscles which should not be in the pattern is as important as the excitation of the muscles which participate in the pattern. Thousands of repetitions are required to begin to form an engram and millions of repetitions are necessary to perfect it. Coordination is developed in proportion to the number of repetitions of an engram practiced just below the maximal level of ability to perform. The performance of our strongest, fastest, and most complex motor patterns is a function of the extrapyramidal system.