SPINAL KITTENS - EFFECT OF CLAMPING OF THORACIC AORTA ON LONG-TERM INCREASES IN ELECTROMYOGRAMS DUE TO A CONDITIONING ROUTINE

Conditioning and pseudoconditioning routines have different effects on EMG responses recorded from the semitendinosus muscle of spinal kittens pinched on tail (CS) and toe (US) 50 times daily for 5 days. The response to tail pinches habituates during each day. However, conditioning routines cause increases in responses between days 5 and 1. Pseudoconditioning routines in which CS and US are separated by 10 sec have no comparable effect. Clamping thoracic aortas for 30 min severely reduces conditioning routines' effectiveness in producing increased responses. Because thoracic clamping selectively destroys the spinal cord interneurons, we conclude that interneurons are essential to the production by conditioning routines of long-term increases in responsiveness of isolated lumbosacral spinal cord. © 1969.