In a phenomenon known as 'social buffering' in various species, signals from a conspecific animal can mitigate stress responses. This buffering can be achieved either by 'pair-housing' after a stressful event or by 'pair-exposure' to an acute stressor with a conspecific animal. In this study, we compared the impacts of these two types of social buffering on auditory conditioned fear responses in male rats. When subjects were exposed to an auditory conditioned stimulus (CS) that had been paired with foot shocks on the previous day, they clearly exhibited behavioral (freezing), autonomic (aggravated stress-induced hyperthermia) and neural (Fos expression) responses. Pair-housing for 24 h with an unfamiliar rat following fear conditioning resulted in a suppressed autonomic, but not behavioral, response, with Fos expression in the lateral nucleus of the amygdala and ventrolateral periaqueductal gray. On the other hand, pair-exposure to the CS with an unfamiliar rat eliminated the behavioral, but not the autonomic, response, with Fos expression in the basal nucleus of the amygdala and infralimbic region of the prefrontal cortex. Furthermore, subjects that had been pair-housed and then pair-exposed showed no behavioral, autonomic or neural responses, suggesting that the combination of the two procedures can completely block the fear conditioning sequence. These results demonstrate that two types of social buffering differentially relieve conditioned fear responses, by influencing different neural pathways in the amygdala.

We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at the RIKEN Radioactive Isotope Beam Factory by using the time-of-flight magnetic-rigidity technique. The atomic mass excesses of ^{55-57}Ca are determined for the first time to be -18650(160), -13510(250), and -7370(990)  keV, respectively. We examine the emergence of neutron magicity at N=34 based on the new atomic masses. The new masses provide experimental evidence for the appearance of a sizable energy gap between the neutron 2p_{1/2} and 1f_{5/2} orbitals in ^{54}Ca, comparable to the gap between the neutron 2p_{3/2} and 2p_{1/2} orbitals in ^{52}Ca. For the ^{56}Ca nucleus, an open-shell property in neutrons is suggested.

The relationship between a social partner's stress status and the social buffering effect was examined in adult male Wistar rats. Fear-conditioned rats were exposed to the same context along with either a shocked or nonshocked conspecific partner. Changes in body temperature and behavioral responses were monitored in order to compare the effects of social buffering, and the Fos protein in the paraventricular nucleus was immunostained. The presence of the partner rat attenuated stress-induced hyperthermia, as well as behavioral responses and Fos expression in response to the fearful context, and nonshocked partners were more effective than shocked partners. These findings suggest that the social buffering effect depends on the stress status of the accompanying conspecific animal.

KIYOKAWA, Y. and HENNESSY, M.B. Comparative studies of social buffering: A consideration of approaches, terminology, and pitfalls…NEUROSCI BIOBEHAV REV XXX-XXX, .- Over the past decades, there has been an increasing number of investigations of the impact of social variables on neural, endocrine, and immune outcomes. Among these are studies of "social buffering"-or the phenomenon by which affiliative social partners mitigate the response to stressors. Yet, as social buffering studies have become more commonplace, the variety of approaches taken, definitions employed, and divergent results obtained in different species can lead to confusion and miscommunication. The aim of the present paper, therefore, is to address terminology and approaches and to highlight potential pitfalls to the study of social buffering across nonhuman species. We review and categorize variables currently being employed in social buffering studies and provide an overview of responses measured, mediating sensory modalities and underlying mechanisms. It is our hope that the paper will be useful to those contemplating examination of social buffering in the context of their own research.

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