REFLEXES IN SPINAL STANDING OF THE CAT

Abstract

In 18 chronic spinal cats transected in the lower thoracic segments, anemic decerebrations were performed. The extensor quadriceps and the flexor semitendinosus were isolated by dissection and the animal was placed upright in a hammock. With the right hind limb securely fixed, kymographic tracings were made of the reflex responses in these muscles. In the same animal, it was possible to apply normal stimuli to the ipsilateral and contralateral limbs and also to use electrical stimulation to the various nerves. The Stutz positive reflex with cocontraction of the flexors and extensors of the knee was not elicited on stimulation of the pads of the foot. In some preparations, a portion of the pattern was present as an effect on the extensor responses of the quadriceps, either an ipsilateral extension or a facilitation of the crossed extensor reflex, both in amplitude and duration. At times in the presence of a well-developed stretch reflex in the gastrocnemius, no response could be obtained from Stiitz positive stimulation; at other times ipsilateral flexion was seen. Crossed flexion was observed but the crossed responses to normal and electrical stimulation were generally extensor in type.