Neonatal handling: An overview of the positive and negative effects

Abstract

As one of the first rodent models designed to investigate the effects of early-life experiences, the neonatal handling paradigm has helped us better understand how subtle changes in the infant environment can powerfully drive neurodevelopment of the immature brain in typical or atypical trajectories. Here, we review data from more than 50 years demonstrating the compelling effects of neonatal handling on behavior, physiology, and neural function across the lifespan. Moreover, we present data that challenge the classical view of neonatal handling as an animal model that results only in positive/beneficial outcomes. Indeed, the overall goal of this review is to offer the suggestion that the effects of early-life experiences—including neonatal handling—are nuanced rather than unidirectional. Both beneficial and negative outcomes may occur, depending on the parameters of testing, sex of the subject, and neurobehavioral system analyzed.

O efeito da manipulação sobre o sono do recém-nascido prematuro

“…Therefore, the harmful effects of deprivation, such as impaired development, especially sensorineural, weight gain, length of hospital stay and irritability, among others, should be considered. (31)(32) The preterm infants remained, on average, more time in QS, followed by AS and IS, contrary to a study that reported the predominance of AS, during approximately 80% of the total time, mainly in preterm infants with lower gestational ages. Studies have found that as newborns mature neurologically, there is an increase in the proportion of AS, (22,31) which matches the results of the present study, since the preterm infants studied were late preterm.…”

“…(5,10,(29)(30) The preterm infants who were examined slept approximately 57.2% of the 24-hour period, diverg-ing from the literature which indicated that preterm infants, at different gestational ages, had an average of 16 to 18 hours of sleep, corresponding to approximately 70% of 24 hours. (2,31,32) The preterm infants experienced sleep deprivation, even without identification of the influence of handling procedures. Therefore, the harmful effects of deprivation, such as impaired development, especially sensorineural, weight gain, length of hospital stay and irritability, among others, should be considered.…”

Effects of cross-fostering on play and anxiety in juvenile Fischer 344 and Lewis rats

“…In particular, rats that receive more licking and grooming as pups tend to be less fearful [35], are more likely to explore a novel environment [36], and have an attenuated startle response [37] when tested as adults and compared to rats raised by dams that engage in less licking and grooming. Rats that experience brief (e.g., 15 minutes) periods of maternal separation during the first 2 weeks of life are also less anxious and less stressed as adults [38–41]. …”

When mothering goes awry: Challenges and opportunities for utilizing evidence across rodent, nonhuman primate and human studies to better define the biological consequences of negative early caregiving

“…This theory, initially proposed by Myron Hofer, has since been substantiated by a multitude of studies across a range of different mammalian species (e.g. (Hofer, 1984; Howell and Sanchez, 2011; Kuhn et al, 1991; Raineki et al, 2014; Rincon-Cortes and Sullivan, 2014). Extending from this foundational theory, variations in caregiving quality and consistency, particularly extreme deviations from the unique species typical pattern of caregiving early in life, further shape an infant's underlying neurobiological processes, leading to life-long alterations.…”