Exp Neurol. 1982 Oct;78(1):176-89.

Normal development of motor behavior in the rat and effect of midthoracic spinal hemisection at birth on that development.

Prendergast J, Shusterman R.

PMID:

7117479

[PubMed - indexed for MEDLINE]

Early Hum Dev. 1993 Sep;34(1-2):89-100.

Development of locomotion in the rat: the significance of early movements.

Westerga J, Gramsbergen A.

Source

University Hospital, Department of Developmental Neurology, Groningen, Netherlands.

Abstract

The development of the nervous system is determined by an interaction between genetic and epigenetic factors. We investigated the possible role of proprioceptive afferent input in the development of locomotion in the rat. Kinematic analysis of locomotion in normal rats reveals a marked transition from immature overground locomotion into the adult pattern around the 15th postnatal day. Around this age, the timing of EMG activity in the tibialis anterior and the gastrocnemius muscle in the hindpaw gains accuracy and the intensity of the EMG increases. In the soleus muscle we observed an increased regularity in the shape of individual motor unit potentials. Neuroanatomical research revealed the occurrence of dendrite bundles in the motoneuronal pool of the soleus muscle pool from the 16th day as the result of a reorganisation. Immobilisation of one hindlimb in an extended position by casts around the leg from the first till the 20th postnatal day does not interfere with the development of dendrite bundles in the soleus motoneuronal pool. However, we demonstrated long lasting abnormalities in the timing of the EMG activation patterns in the gastrocnemius and the tibialis anterior muscles. It is conceivable that the experimental interference with afferent feed back is the causative factor of these functional abnormalities.

PMID:

8275886

[PubMed - indexed for MEDLINE]

Brain Res Brain Res Rev. 1998 Nov;28(1-2):35-43.

Role of gravity in the development of posture and locomotion in the neonatal rat.

Clarac F, Vinay L, Cazalets JR, Fady JC, Jamon M.

Source

CNRS (UPR 9011), Neurobiologie et Mouvements, 31 chemin Joseph Aiguier, BP 71, F-13402, Marseille cedex 20, France. clarac@lnf.cnrs-mrs.fr

Abstract

This report describes the early motor behaviour in the neonatal rat in relation with the maturation of sensory and motor elements of the central nervous system (CNS). The role of vestibular information during the week before (E14-21) and the 2 weeks after (P0-15) birth will be considered. There is a rostro-caudal gradient in the maturation of posture and locomotion with a control of the head and forelimbs during the first postnatal week and then a sudden acceleration in the functional maturation of the hindlimb. At birth, the neonatal rat is blinded and deaf; despite the immaturity of the other sensory systems, the animal uses its olfactory system to find the mother nipple. Vestibular development takes place between E8 and P15. Most descending pathways from the brainstem start to reach the lumbar enlargement of the spinal cord a few days before birth (reticulo-, vestibulospinal pathways as well as the serotonergic and noradrenergic projections); their development is not completed until the end of the second postnatal week. At birth, in an in vitro preparation, a locomotor activity can be evoked by perfusing excitatory amino acids and serotonin over the lumbar region. The descending pathways which trigger the activity of the CPG are also partly functional. At the same age both air stepping and swimming can be induced. Complex locomotion such as walking, trotting and galloping start later because it requires the maturation of the vestibular system, descending pathways and postural reflex regulation. The period around birth is critical to properly define how the vestibular information is essential for the structuring of the motor behaviour. Different types of experiments (hypergravity, microgravity) are planned to test this hypothesis.

Copyright 1998 Elsevier Science B.V.

PMID:

9795120

[PubMed - indexed for MEDLINE]

Eur J Pharmacol. 1983 Aug 5;91(4):391-7.