Insulin receptors (IRs) are expressed in discrete neuronal populations in the central nervous system, including the hippocampus. To elucidate the functional role of hippocampal IRs independent of metabolic function, we generated a model of hippocampal-specific insulin resistance using a lentiviral vector expressing an IR antisense sequence (LV-IRAS). LV-IRAS effectively downregulates IR expression in the rat hippocampus without affecting body weight, adiposity, or peripheral glucose homeostasis. Nevertheless, hippocampal neuroplasticity was impaired in LV-IRAS–treated rats. High-frequency stimulation, which evoked robust long-term potentiation (LTP) in brain slices from LV control rats, failed to evoke LTP in LV-IRAS–treated rats. GluN2B subunit levels, as well as the basal level of phosphorylation of GluA1, were reduced in the hippocampus of LV-IRAS rats. Moreover, these deficits in synaptic transmission were associated with impairments in spatial learning. We suggest that alterations in the expression and phosphorylation of glutamate receptor subunits underlie the alterations in LTP and that these changes are responsible for the impairment in hippocampal-dependent learning. Importantly, these learning deficits are strikingly similar to the impairments in complex task performance observed in patients with diabetes, which strengthens the hypothesis that hippocampal insulin resistance is a key mediator of cognitive deficits independent of glycemic control.

Central nervous system (CNS) complications resulting from diabetes is a problem that is gaining more acceptance and attention. Recent evidence suggests morphological, electrophysiological and cognitive changes, often observed in the hippocampus, in diabetic individuals. Many of the CNS changes observed in diabetic patients and animal models of diabetes are reminiscent of the changes seen in normal aging. The central commonalities between diabetes-induced and age-related CNS changes have led to the theory of advanced brain aging in diabetic patients. This review summarizes the findings of the literature as they relate to the relationship between diabetes and dementia and discusses some of the potential contributors to diabetes-induced CNS impairments.

Evidence for altruistic behaviors in rats has been continually building over many years, with a large surge in the past 10 years. Many researchers have posited that rats have the cognitive capabilities to engage in these altruistic behaviors that were at one time only attributed to species that are more complex. The results of many of the studies on altruistic behaviors in rats show parallels with non-human primate studies suggesting that what has been observed in rats is indeed altruism as it has been defined in primates. Research focused on rat altruism has provided evidence that these behaviors are influenced by familiarity, similar to findings among primates. Other evidence for altruistic behavior in rats is apparent in their ability to apply a costbenefit analysis when an opportunity to provide help is presented. There is also evidence that rats rely on previous experiences and predictions of future behaviors of others to make judgments when engaging in altruistic behaviors. Studies have also shown that rats exhibit these altruistic behaviors without the presence of a tangible reward, a primary component in the definition of altruism. The findings presented and the parallels with non-human primate studies provide good evidence that rats are capable of engaging in altruistic behaviors, and that rats may be good candidates for an alternative animal model for further studying altruism. Having rats as a valid model for the study of altruism opens the door to study facets of this behavior that otherwise would not be able to be studied. Because of the important contribution of altruism to social interactions, better understanding of this behavior will hopefully aid in positively influencing social societies such as those lived in by humans and other primates.

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The present study investigated relations among parenting styles and emotion regulation, trait emotion, and general well-being among 153 emerging adults. Two path models were tested, finding that parenting styles contributed to multiple pathways to emotional regulation. As expected, not only did participants who reported high levels of authoritative parenting endorse high levels of positive emotion, they also reported lower levels of emotional control and emotional self-awareness. These low levels were, in turn, associated with emotional well-being. Permissive parenting positively predicted negative emotion. Because authoritarian parenting did not directly predict trait emotion, a closer examination was conducted, showing that outcomes associated with this parenting style depended upon self-reported emotional control and trait emotion. The findings suggest that the effects of authoritarian parenting depend upon the emotional climate established in the family, a factor that may help to explain variability in outcomes for children of authoritarian parents depending upon socioeconomic status and ethnicity.