Quality of early-life maternal care predicts empathy-like behavior in adult male rats: Linking empathy to BDNF gene expression in associated brain regions

Prosocial behaviors in rodents

Prosocial behaviors (i.e., actions that benefit others) are central for social interactions in humans and other animals, by fostering social bonding and cohesion. To study prosociality in rodents, scientists have developed behavioral paradigms where animals can display actions that benefit conspecifics in distress or need. These paradigms have provided insights into the role of social interactions and transfer of emotional states in the expression of prosociality, and increased knowledge of its neural bases. However, prosociality levels are variable: not all tested animals are prosocial. Such variation has been linked to differences in animals' ability to process another's state as well as to contextual factors. Moreover, evidence suggests that prosocial behaviors involve the orchestrated activity of multiple brain regions and neuromodulators. This review aims to synthesize findings across paradigms both at the level of behavior and neural mechanisms. Growing evidence confirms that these processes can be studied in rodents, and intense research in the past years is rapidly advancing our knowledge. We discuss a strong bias in the field towards the study of these processes in negative valence contexts (e.g., pain, fear, stress), which should be taken as an opportunity to open new venues for future research.

Shaping the development of complex social behavior

Early life experiences can have an enduring impact on the brain and behavior, with implications for stress reactivity, cognition, and social behavior. In particular, the neural systems that contribute to the expression of social behavior are altered by early life social environments. However, paradigms that have been used to alter the social environment during development have typically focused on exposure to stress, adversity, and deprivation of species-typical social stimulation. Here, we explore whether complex social environments can shape the development of complex social behavior. We describe lab-based paradigms for studying early life social complexity in rodents that are generally focused on enriching the social and sensory experiences of the neonatal and juvenile periods of development. The impact of these experiences on social behavior and neuroplasticity is highlighted. Finally, we discuss the degree to which our current approaches for studying social behavior outcomes give insight into "complex" social behavior and how social complexity can be better integrated into lab-based methodologies.

Four weeks of light-intensity exercise enhances empathic behavior in mice: The possible involvement of BDNF

Empathy is one of the essential functions of mammals for maintaining relationships with others. Physical activity contributes to enhancing empathic attitude and behavior; however, it is remained to cover the effective intensity of exercise on mammal empathy. Here, we tested the effects of light-intensity exercise, which has beneficial effects on expressing neurotrophic factors in the brain, on empathic behavior. Eight-week-old male C57BL/6 mice were subjected to forced wheel running at light-intensity (7.0 m/min, 30 min/day, 5 days/week) for 4 weeks. Then, all mice were subjected to helping behavior to evaluate their empathic behavior. The insular cortex was collected for analyzing the expressions of mRNA and miRNA. Four weeks of light-intensity exercise enhanced helping behavior. Exercised mice exhibited higher Bdnf gene expressions in the insular cortex than sedentary mice. In addition, there was a significant positive correlation between mRNA levels of Fndc5 and Bdnf in the insular cortex. Based on miRNA sequencing, 26 out of 51 miRNAs were significantly upregulated, and 25 out of 51 miRNAs were significantly downregulated in the insular cortex of mice with exercise. There were significant correlations between 11 out of 51 miRNAs and helping behavior; miR-486a-3p, which relates to FNDC5 expression, was contained. These results imply that miR-486a-3p/Fndc5/Bdnf pathway in the insular cortex would be a possible target for treating empathy.