The development of righting reflexes in the pouch young of the marsupial Dasyurus hallucatus

Abstract

The development of righting was studied in the young of Dasyurus hallucatus, a small marsupial from northern Australia. Young were tested from birth to weaning. Righting began at 40 days, when tactile input on the snout triggered rotation to prone. Over the next 15-20 days, asymmetrical tactile input on the body triggered righting movements by the hindlegs (and later by the forelegs). Vestibular righting reflexes developed after these tactile righting reflexes. Furthermore, asymmetrical vestibular righting (i.e., when the young are held laterally in the air) developed before symmetrical vestibular righting (i.e., when held downward by the pelvis or placed supine in water). Vestibular righting triggered by falling supine in the air did not develop until about 80 days. This study further demonstrates that righting behavior does not consist of a single, integrated motor pattern, but a suite of motor patterns having independent control mechanisms and patterns of development.

Features of the structural development of the inferior colliculus in relation to the onset of hearing in a marsupial: The Northern Quoll,Dasyurus hallucatus

“…It becomes accustomed to humans so that, because of its size, it is suitable as a laboratory species. It is valuable for developmental studies (Aitkin et al, 1991(Aitkin et al, , 1994aNelson, 1989, 1992;Nelson, 1987Nelson, , 1992Pellis et al, 1992) because it bears a litter of eight young which appear in a shallow pouch after 21-25 days in utero (Nelson, unpublished observations). After about 40 more days, the young move from one nipple to another and could be lost from the pouch, but the mother is able to retrieve the pouch-young because the latter emit characteristic isolation sounds which are closely matched in spectra to the best frequency of the mother's audiogram (Aitkin et al, 1994b) and would thus be highly audible to the mother.…”

How the neonatal rat gets to the nipple: Common motor modules and their involvement in the expression of early motor behavior

“…Other investigators have commented on the existence of common motor modules during early ontogeny and suggested that they should be considered as an ancestral basis for diversification of motor activity in later phases in ontogeny (Eilam & Golani, 1988;Golani, 1992;Robinson & Smotherman, 1992a, 1992b. The manifestation of these motor modules in different species which are remote in a phylogenetic sense (Pellis et al, 1992) lends support to the notion that the modules are of fundamental importance during early mammalian development.…”

“…Results from the present experiment, together with the results from studies of righting behavior (Pellis et al, 1991) add rotation along the body axis as another dimension of movement in which cephalocaudal activity is apparent (bodywise system of reference for this movement). Cephalocaudal rotation is a basic motor module and a component of several types of righting (Pellis, Pellis, & Nelson, 1992;Pellis et al, 1991).…”

Development of the Vestibular Apparatus and Central Vestibular Connections in a Wallaby <i>(Macropus eugenii)</i>

“…Those authors also found a bilateral brainstem projection to the vestibular ganglion in newborn opossums, which does not appear to be present in adults. Despite these findings, in marsupials traditional righting reflexes have not been detected until several weeks after birth [Langworthy, 1928;Larsell et al, 1935;Pellis et al, 1992].…”