Effects of Preweaning Sensorimotor Stimulation on Behavioral and Neuronal Development in Motor and Visual Cortex of the Rat

Abstract

The present study investigates the effects of early sensorimotor stimulation on behavioral and neuronal cytodifferentiation in motor and visual cortex of lactating rats. Seventy-two male and female Sprague-Dawley albino rats were systematically submitted to environmental stimulation during the early postnatal period (postnatal days 5–21). On postnatal day 22, four behavioral tests were performed (open field, narrow path crossing, hind limb support and ascending on a rope). In order to evaluate dynamic neuronal changes induced by sensorimotor enrichment, brains were stained through the Golgi-Cox-Sholl method. Morphometric studies were carried out in pyramidal neurons located in motor and visual cortical layers II and III, by measuring their basal dendritic length and branching. Further, wide cortical field studies were performed with the aim of evaluating the degree of development reached by clusters of pyramidal cells. The results indicate that sensorimotor stimulation carried out during the suckling period produced a significant increase in neuronal cytodifferentiation as observed in single cell studies. However, collective neuronal evaluations yielded less significant results. Consistently, rats exposed to enriched environments showed a better performance in behavioral adaptive responses.

Non-nutritive suck parameters in preterm infants with RDS

“…Unfortunately, these procedures produce unexpected tactile stimulation and movement restriction of the lower face that may negatively affect the development of the sCPG (Comrie & Helm, 1997;Finan & Barlow, 1996). In animal models, the combination of sensory deprivation and motor restriction has been shown to disrupt development of key brain structures involved in sensorimotor control, including motor cortex and cerebellum (Pascual & Figueroa, 1996;Pascual et al, 1993;Pascual et al, 1998). This is consistent with the notion of a critical period during early postnatal life, when manipulations in trigeminal sensory systems may significantly alter the structure and function of the developing brain (Bosma, 1973).…”

Respiratory distress syndrome degrades the fine structure of the non-nutritive suck in preterm infants

“…Support for this hypothesis is derived from studies of brain development in animal models. For example, the combination of sensory deprivation and motor restriction in rat has been shown to disrupt development of key brain structures involved in sensorimotor control, including motor cortex and cerebellum (Pascual et al, 1998(Pascual et al, , 1993Pascual and Figueroa, 1996). This is consistent with the notion of a critical period during early postnatal life, when manipulations in trigeminal sensory systems may result in drastic effects in the structure and function of the developing brain.…”

Synthetic orocutaneous stimulation entrains preterm infants with feeding difficulties to suck

“…26,27 Conversely, sensorimotor enhancement during the early postnatal period produces elaboration of pyramidal neuron dendritic length and arborization in motor cortex and enhanced behavioral motor responses. 28 Critical periods are described as windows in development in which systems or processes are particularly vulnerable. 9 Critical periods have been demonstrated for ocular dominance, human language, speech perception, and sound localization.…”