Abstract
Magnus and Radamaker 1 have demonstrated the dependency of the body righting reflexes from the body and of the labyrinthine righting reflexes upon the mid-brain. Their experiments indicated the dependency of these reflexes on the red nuclei. Ingram and Ranson 2 recently report intact righting reflexes and movements of progression after bilateral destruction of the red nuclei; our experiments, performed independently and using quite a different approach, verify and extend Ingram's and Ranson's observations.
An unoperated animal exhibits the following reactions: (1) it rights the body in falling through the air a short distance, and lights on its feet; (2) when placed on the side, the fore quarters right after the raising of the head, by a rolling, lifting motion in which the fore limbs do not participate to a great degree. The hind quarters follow the fore quarters in like manner. The head, the fore quarters, or the hind quarters will right independently if the other parts are passively fixed. As soon as righting is completed, progression proceeds. (3) If in the standing position, the hind quarters are grasped and passively rotated to one side, the head and fore quarters resist this action by a compensatory rotation in the opposite direction. (4) If the animal is suspended vertically in the air by the hips, the body hangs straight and the head is dorsi-flexed. (When struggling movements are absent.) (5) Equal resistance is met in bowing the body—the vertebral axis—to either the right or the left side.
The above described reactions have been found to be essentially unimpaired after the following operative procedures: (Each procedure has been carried out in 2 or more animals, and in most instances in as many as 6 to 8 animals.†)
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