Hippocampal memory processes are modulated by insulin and high-fat-induced insulin resistance

Insulin regulates glucose uptake and storage in peripheral tissues, and has been shown to act within the hypothalamus to acutely regulate food intake and metabolism. The machinery for transduction of insulin signaling is also present in other brain areas, particularly in the hippocampus, but a physiological role for brain insulin outside the hypothalamus has not been established. Recent studies suggest that insulin may be able to modulate cognitive functions including memory. Here we report that local delivery of insulin to the rat hippocampus enhances spatial memory, in a PI-3-kinase dependent manner, and that intrahippocampal insulin also increases local glycolytic metabolism. Selective blockade of endogenous intrahippocampal insulin signaling impairs memory performance. Further, a rodent model of type 2 diabetes mellitus produced by a high-fat diet impairs basal cognitive function and attenuates both cognitive and metabolic responses to hippocampal insulin administration. Our data demonstrate that insulin is required for optimal hippocampal memory processing. Insulin resistance within the telencephalon may underlie the cognitive deficits commonly reported to accompany type 2 diabetes.     

Intent to harm or injure? Gender and the expression of anger

Gender differences in aggressive behaviour but not in anger suggest that women may express anger through behaviours that lack intent to harm or injure. Angry behaviours (injurious and noninjurious) were rated in terms of their likelihood of use when angry (N=888). Confirmatory factor analysis revealed a direct aggression factor and two further scales: explosive acts (e.g. throwing objects when alone) and defusing acts (e.g. talking to a third party). Men exceeded women on direct aggression and explosive acts, whereas women exceeded men on defusing acts. Expressive beliefs about aggression (as a loss of self-control) were higher among women and strongly associated with use of defusing acts and the avoidance of direct aggression. Instrumental beliefs about aggression (as a means of control over others) were higher among men and showed the opposite pattern of associations. We highlight the need for further work on actors' intention in relation to angry behaviours and the impact of context on these intentions.     

Egos inflating over time: a cross-temporal meta-analysis of the Narcissistic Personality Inventory

ABSTRACT A cross-temporal meta-analysis found that narcissism levels have risen over the generations in 85 samples of American college students who completed the 40-item forced-choice Narcissistic Personality Inventory (NPI) between 1979 and 2006 (total n =16,475). Mean narcissism scores were significantly correlated with year of data collection when weighted by sample size (β=.53, p <.001). Since 1982, NPI scores have increased 0.33 standard deviation. Thus, almost two-thirds of recent college students are above the mean 1979–1985 narcissism score, a 30% increase. The results complement previous studies finding increases in other individualistic traits such as assertiveness, agency, self-esteem, and extraversion.     

Suicide survivors seeking mental health services: a preliminary examination of the role of an active postvention model

Archival data from suicide survivors presenting for treatment from 1999-2005 at the Baton Rouge Crisis Intervention Center (BRCIC) were used to examine differences in those who received an active model of postvention (APM; n=150) compared to those who received a traditional passive postvention (PP, n=206). APM presented sooner for treatment (48 days) than PP (97 days). APM survivors were more likely to have been the survivor of a violent suicide. APM were more likely than PP to attend survivor support group meetings and APM attended more groups. To better understand the efficacy of APM in helping survivors, a prospective evaluation is needed.     

The signing brain: the neurobiology of sign language

Most of our knowledge about the neurobiological bases of language comes from studies of spoken languages. By studying signed languages, we can determine whether what we have learnt so far is characteristic of language per se or whether it is specific to languages that are spoken and heard. Overwhelmingly, lesion and neuroimaging studies indicate that the neural systems supporting signed and spoken language are very similar: both involve a predominantly left-lateralised perisylvian network. Recent studies have also highlighted processing differences between languages in these different modalities. These studies provide rich insights into language and communication processes in deaf and hearing people.     

New Essays on the Metaphysics of Moral Responsibility

This is the introduction to a volume of new essays in the metaphysics of moral responsibility by John Martin Fischer, Carl Ginet, Ishtiyaque Haji, Alfred R. Mele, Derk Pereboom, Paul Russell, and Peter van Inwagen. I provide some background for the essays, cover the main debates in the metaphysics of moral responsibility, and emphasize some of the authors’ contributions to this area of philosophy.     

Do wild New Caledonian crows (<Emphasis Type="Italic">Corvus moneduloides</Emphasis>) attend to the functional properties of their tools?

New Caledonian crows are the most proficient non-hominin tool manufacturers but the cognition behind their remarkable skills remains largely unknown. Here we investigate if they attend to the functional properties of the tools that they routinely use in the wild. Pandanus tools have natural barbs along one edge that enable them to function as hooking implements when the barbs face backwards from the working tip. In experiment 1 we presented eight crows with either a non-functional (‘upside-down’) or a functional pandanus tool in a baited hole. Four of the crows never flipped the tools. The behaviour of the four flipping birds suggested that they had a strategy of flipping a tool when it was not working. Observations of two of the eight crows picking up pandanus tools at feeding tables in the wild supported the lack of attention to barb direction. In experiment 2 we gave six of the eight crows a choice of either a barbed or a barbless pandanus tool. Five of the crows chose tools at random, which further supported the findings in experiment 1 that the crows paid little or no attention to the barbs. In contrast, a third experiment found that seven out of eight crows flipped non-functional stick tools significantly more than functional ones. Our findings indicate that the crows do not consistently attend to the presence or orientation of barbs on pandanus tools. Successful pandanus tool use in the wild seems to rely on behavioural strategies formed through associative learning, including procedural knowledge about the sequence of operations required to make a successful pandanus tool. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.