Instrumental cardiovascular conditioning: a review.

This paper reviews experiments, hypotheses, and current controversies about instrumental cardiovascular conditioning. Demonstrations of such conditioning in curarized animals challenged a differentiation between instrumental and classical learning on the basis of their respective effector systems but did not prove direct operant learning by the autonomic nervous system. In humans, ethical prohibition of curarization and lack of adequate controls for respiration and muscle tension have resulted in incomplete understanding of the roles of voluntary, somatic mediators. Despite a variety of potential clinical applications of biofeedback, the available literature lacks studies of its efficacy compared to more standard modes of therapy. The physiological mechanisms and central neural pathways involved in instrumental cardiovascular conditioning remain almost totally unknown.