A STUDY OF MOTOR COÖRDINATION AND TONUS IN DEAFFERENTED LIMBS OF AMPHIBIA

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Abstract
Spinal ganglia and dorsal roots were excised from the limb region of toads (Bufo americana, B. fowleri) and axolotls (Amblystoma mexicanum) by an operation avoiding the opening of the vertebral canal. A study of the motor functions of the deafferented limbs from the time immediately after the operation up to several weeks later revealed that in the toad locomotion, limb reflexes and capacity for tonic reactions were not noticeably impaired by unilateral or bilateral deafferentation of fore or hind limbs. Tonic flexion against gravity can be maintained in deafferented and sympathectomized hind limbs for several minutes." As in the toad, locomotor coordination was found to be perfectly normal in the deafferented fore limbs of the axolotl. The results stress the central autonomy of motor patterns and their independence of proprioceptive control in amphibia.