The Disappearing Reflex:

Abstract

The objectives of this article are to examine theoretical views regarding the appearance and disappearance of primitive reflexes and to dsicuss their implications for therapeutic intervention. According to the traditional view, primitive reflexes are inhibited or integrated by highher central nervous system centers. After central nervous system (CNS) damage, these primitive reflexes are released from inhibition by higher centers. This view implies a model of CNS organization for motor control that is hierachially organized. Alternatively, according to the more contemporary systems view, the development of reflexive and volitional behavior is the results of an interaction of central and external environmental influences. Research on primitive stepping indicates that such factors as decreased body mass and practice can contribute to the prolonged retention of this reflex. The systems view implies a distributed control model on CNS motor control in which peripheral and CNS factors participate in the control of movement. if environmental demands can alter reflexive as well as volitional movement, then then traditional view of the relationship between primitive and pathological reflexes is challenged. The systems view and implied distributed control of the CNS should lead therapists to reassess their treatment rationales.