On the Postnatal Development of Postural Mechanisms as Revealed by Electromyography and Myography in Decerebrate Kittens

Abstract

The present paper is one in a series of studies on the postnatal development of postural reflex activity in the kitten. Its aim is to investigate the reactions to decerebration and additional ablation of the anterior lobe of the cerebellum in these animals from birth until they are able to walk and stand. An attempt was made by electromyography and myography to trace the mechanisms behind the different reactions. It is shown that alpha rigidity is present in the newborn kitten while gamma rigidity develops later, appearing first in the forelimbs around a fortnight after birth and in the hindlimbs after three weeks. The missing gamma rigidity in the newborn animal is readily explained by the observation that no tonic stretch reflexes, as revealed by electromyography can be obtained from the muscles concerned with decerebrate rigidity. The tonic stretch reflex develops in a proximo‐distal direction in the limbs as revealed by electromyography and is earlier obtained in the alpha than the gamma animal and earlier in the forelimbs than the hindlimbs. This development thus precedes the gamma rigidity which in its development closely follows that of the animal's ability to use its limbs for walking and standing. It also runs in a cranio‐caudal direction.

Postnatal Maturation of Phrenic, Vagus, and Intercostal Nerves in the Kitten

“…Our results, which are in keeping with Skoglund's (1960) reports, led us to think that there exists a delay between the functional matura tion of thoracic muscle innervation and the innervation of the diaphragm. The postnatal development of the vagus nerve deeply differs from the development of the later nerves.…”

“…The difference between the phrenic nerve and the other spinal nerves (intercostal nerves) may be explained in part by the cephalocaudal maturation as mentioned by Skoglund (1960) and Skoglund and Romero (1965), though this does not fit for the small number of myelinated fibers in the vagus nerve at birth.…”

Morphological and physiological studies of development of the monosynaptic reflex pathway in the rat lumbar spinal cord.

“…This is 1 day later than the first appearance of monosynaptic effects when the dorsal root was stimulated (Fig. 11) Skoglund (1960) reported that the tonic stretch reflex begins to function earlier in proximal muscles than in distal muscles in the kitten. The developmental sequence of projections of primary afferents has also been studied in the thoracic cord by Smith (1983) using HRP techniques.…”

Central effects of 5‐HT on activity of respiratory and hypoglossally innervated muscles in newborn kittens.

“…250-1000 nmol in 0 05 ml artificial cerebrospinal fluid) used in in vitro preparations (NMorin et al 1991). (Trippenbach, Kelly & Marlot, 1985;Wallois, Khater-Boidin, Dusaussoy & Duron, 1993;Khater-Boidin, Wallois, Toussaint & Duron, 1994 (Skoglund, 1960;Duron & Marlot, 1980). Therefore, as postulated by Duron & Marlot (1980), the nervous control of breathing in the newborn may well depend essentially on the non-specific reticular formation.…”