PROPRIOCEPTIVE MODIFICATION OF REFLEX PATTERNS

Abstract

In cats and monkeys under Dial, afferent stimulation of arm nerves elicits either a Biceps-extensor carpi-brachioradialis reflex response pattern (electromyograms) or a Triceps-flexor carpi pattern, depending on the nerve chosen. These are the same patterns elicited by cortical stimulation or by direct muscle stretch. In the hind leg, appropriate choice of afferent nerve leads to a response of tibialis anticus or gastrocnemius (with hamstrings in either case). The reflex response of all muscles in any one complex is greater (greater EMG amplitude) if any one muscle in the complex is directly loaded: This is attributed to greater excitation of proprioceptors in the loaded (stretched) muscle. It appears that proprioceptive facilitation extends beyond the limits of the monosynaptic myotatic reflex. Multisynaptic reflexes arising in muscle proprioceptors may play a more important part in muscle coordination than is customarily assumed.