Amygdalar Volume in Borderline Personality Disorder With and Without Comorbid Post-traumatic Stress Disorder: A Meta-analysis

IntroductionFour studies have found a smaller amygdalar volume in patients with borderline personality disorder (BPD) relative to controls, whereas four other studies have found similar amygdalar volume in BPD patients relative to controls. This study aims to compare amygdalar volumes of BPD patients with controls, and also to compare BPD patients with and without post-traumatic stress disorder (PTSD) with controls in order to determine whether PTSD can explain the heterogeneity of findings.MethodSystematic review and meta-analysis of magnetic resonance imaging studies that measured amygdalar volumes in BPD patients and healthy controls.FindingsA significant reduction of amygdalar volumes in BPD patients was confirmed (p < .001). However, data from the studies that discriminated BPD patients with and without PTSD indicated that amygdalar volumes were significantly smaller in BPD patients without PTSD relative to controls (left: p = .02; right: p = .05), but not in BPD patients with PTSD relative to controls (left: p = .08; right: p = .20).ConclusionThis meta-analysis suggests that amygdalar volumes are reduced in patients with BPD. This pattern is confirmed in BPD patients without PTSD, but not in BPD patients with PTSD, raising the possibility that reduced amygdalar volume in BPD patients cannot be explained by comorbid PTSD.     

On the function of redfronted lemur’s close calls

In order to maintain group cohesion, many social mammals and birds regularly produce close calls. In some primate species, close calls appear to have a dual function: calls addressed at a broad class of targets serve to maintain group cohesion, whereas the same calls directed at a specific target serve to regulate subsequent social interactions. Redfronted lemurs (Eulemur rufifrons) produce different types of close calls: grunts, long grunts, hoos and meows. In order to study the function of these calls, we conducted focal observations and vocal recordings from eight adult males and females out of four social groups in Kirindy Forest, Western Madagascar. Redfronted lemurs produce long grunts, hoos and meows at relatively low rates during foraging, resting or group movements, respectively. Grunts were given most often and more or less constantly during foraging and traveling. Calling rate increased when the risk of separation increased and may thus promote group cohesion. Grunts given during approaches of other group members resulted more often in friendly interactions than approaches that were not accompanied by a grunt. Thus, redfronted lemurs produce specific but also generic contact calls, whereas the latter calls have a dual function that varies depending on the addressed audience: they act as an auditory beacon to maintain group cohesion and serve as signals of benign intent to avoid costly conflicts and facilitating social interactions.     

You sound familiar: carrion crows can differentiate between the calls of known and unknown heterospecifics

In group-living animals, it is adaptive to recognize conspecifics on the basis of familiarity or group membership as it allows association with preferred social partners and avoidance of competitors. However, animals do not only associate with conspecifics but also with heterospecifics, for example in mixed-species flocks. Consequently, between-species recognition, based either on familiarity or even individual recognition, is likely to be beneficial. The extent to which animals can distinguish between familiar and unfamiliar heterospecifics is currently unclear. In the present study, we investigated the ability of eight carrion crows to differentiate between the voices and calls of familiar and unfamiliar humans and jackdaws. The crows responded significantly more often to unfamiliar than familiar human playbacks and, conversely, responded more to familiar than unfamiliar jackdaw calls. Our results provide the first evidence that birds can discriminate between familiar and unfamiliar heterospecific individuals using auditory stimuli.     

Scientific reasoning in early and middle childhood: The development of domain‐general evidence evaluation,experimentation, and hypothesis generation skills

According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect covariation, and non‐covariation evidence emerges, (b) when experimentation emerges, (c) when hypothesis generation skills emerge, and (d), whether these abilities develop synchronously during childhood. We administered three scientific reasoning tasks referring to the three components to 223 children of five age groups (from age 4.0 to 13.5 years). Our results show that the three cognitive components of domain‐general scientific reasoning emerge asynchronously. The development of domain‐general scientific reasoning begins with the ability to handle unambiguous data, progresses to the interpretation of ambiguous data, and leads to a flexible adaptation of hypotheses according to the sufficiency of evidence. When children understand the relation between the level of ambiguity of evidence and the level of confidence in hypotheses, the ability to differentiate conclusive from inconclusive experiments accompanies this development. Implications of these results for designing science education concepts for young children are briefly discussed.     

Culture,morality, and the effect of prosocial behavior motivation on positive affect

We investigated the effect of culture, moral discourse, and motivation to engage in prosocial behavior on benefactors’ positive affect. Participants from three cultures (Japan, Romania, and the United States) responded to scenarios in which they could perform small acts of kindness for different targets. A stronger relationship between agentic and obligated motivation to perform acts of kindness, as well as between obligated motivation and positive affect, was observed for participants from Japan, and for individuals with higher endorsement of the Community Ethic. Agentic motivation to engage in prosocial behavior was related to benefactors’ positive affect, regardless of relationship type.