Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Implicit meaning in 18‐month‐old toddlers

A substantial body of evidence demonstrates that infants understand the meaning of spoken words from as early as 6 months. Yet little is known about their ability to do so in the absence of any visual referent, which would offer diagnostic evidence for an adult‐like, symbolic interpretation of words and their use in language mediated thought. We used the head‐turn preference procedure to examine whether infants can generate implicit meanings from word forms alone as early as 18 months of age, and whether they are sensitive to meaningful relationships between words. In one condition, toddlers were presented with lists of words taken from the same taxonomic category (e.g. animals or body parts). In a second condition, words taken from two other categories (e.g. clothes and food items) were interleaved within the same list. Listening times were found to be longer in the related‐category condition than in the mixed‐category condition, suggesting that infants extract the meaning of spoken words and are sensitive to the semantic relatedness between these words. Our results show that infants have begun to construct the rudiments of a semantic system based on taxonomic relations even before they enter a period of accelerated vocabulary growth.     

Protection of Children from Physical Maltreatment in Canada: An Evaluation of the Supreme Court's Definition of Reasonable Force

In 2004, the Supreme Court of Canada set out seven criteria to distinguish reasonable from abusive corrective force with children. We tested the validity of those criteria by mapping them onto a nationally representative data set of substantiated cases of physical abuse. The court's criteria defining reasonable force actually characterized the majority of cases of child physical maltreatment in Canada. These cases were more likely to be characterized by the use of spanking in the family than by each of the criteria set out by the Supreme Court. One in five cases was not characterized by any of the court's criteria, and virtually none were characterized by all of them. The findings provide stronger support for abolishing physical punishment than for legal attempts to narrow its definition.     

The Stability of Peer Sociometric Ratings Across Ecological Settings

Although children's peer relations extend beyond the classroom, researchers have focused almost exclusively on evaluting sociometric status within the school setting. In the present study, a roster-and-rating method was used to assess the relationship between the sociometric status of 20 fifth-grade students in the classroom and in adult supervised activity groups outside of school. In addition, the 6-month stability of peer sociometric ratings in school was assessed. The correlational results showed that a child's sociometric standing in the classroom was a strong predictor of his or her standing in outside groups, and that the 6-month stability of peer sociometric ratings at school was quite high. The results are encouraging for researchers who use classroom sociometric ratings as global indices of peer relations.     

Parent or community: Where do 20-month-olds exposed to two accents acquire their representation of words?

The recognition of familiar words was evaluated in 20-month-old children raised in a rhotic accent environment to parents that had either rhotic or non-rhotic accents. Using an Intermodal Preferential Looking task children were presented with familiar objects (e.g. 'bird') named in their rhotic or non-rhotic form. Children were only able to identify familiar words pronounced in a rhotic accent, irrespective of their parents' accent. This suggests that it is the local community rather than parental input that determines accent preference in the early stages of acquisition. Consequences for the architecture of the early lexicon and for models of word learning are discussed.