The cardiac component of the orienting reflex at different age periods

Summary

The cardiac component of the orienting reflex is manifested by tachycardia in dogs under 16–18 days of age, i.e., at the period of sympathetic control of cardiac activity. From the 16th–18th day of life and especially from the age of 2.5–3 months, i.e., when the vagus tone appears and consolidates, the cardiac component of the orienting reflex is manifested by bradycardia. In the mechanism of effecting the cardiac component of the orienting reflex a considerable role is played by the motor component of the reaction. The cardiac component (bradycardia) of the reaction was absent in a special experimental series in which the possibility of effecting the motor component of the orienting reflex was excluded (experiments on puppies denervated while young and on puppies in which the skeletal muscles of the anterior and posterior extremities were worked by means of a myorelaxant).