Investigating the Behavioral, Physiological, and Neural Consequences of Threat to a Social Bond Open Access

Sahni, Aashna (Spring 2021)

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Romantic jealousy is a complex social emotion induced by a threat to a valued relationship due to a rival. Jealousy serves an important adaptive function in keeping a partner in the relationship. However, jealousy can also elicit violent and aggressive behaviors. Therefore, it is important to understand the neurobiological basis of jealousy to provide support to those who experience it. Jealousy occurs in the context of long-term, socially complex relationships with a strong attachment bond. Socially monogamous prairie voles form pair bonds with their partners; this exclusive relationship between partners is characteristic of complex social species like humans. Therefore, voles serve as a model organism to investigate the neural circuitry that evolved into romantic jealousy in humans. In this study, we developed a new model of social threat and investigated the behavioral, physiological, and neural consequences of exposure to a threat to a social bond in male prairie voles. In a pilot experiment, a pair-bonded male and a control male both observed the pair-bonded female interact with the novel male. We observed an increase in the investigative behaviors of the pair-bonded male when the female interacted with a novel male. We further compared the corticosterone levels and c-fos activation in the PVN, lateral septum, amygdala, and BNST between the control and pair-bonded male. We did not observe any significant difference in FOS activation and corticosterone levels between the control and pair-bonded male. We further refined our behavioral test and conducted a choice test in which a pair-bonded male had the choice to investigate either his partner or a stranger female while both the females interacted with a novel male. We observed a significant increase in the male’s investigative behavior towards the stranger female and the novel male. This study opens new avenues for studying the psychosocial impact of a social threat in a socially monogamous rodent. Our data from the pilot experiment shows differences in behavior in response to a social threat. Despite the small effect size, it is indicative of a subtle effect that needs to be further refined to observe robust corresponding changes in brain activation as well.

Table of Contents

Introduction (1)

Emotions in Humans and Animals (1)

Romantic Jealousy in Humans (2)

Social Monogamy and Pair Bonding (3)

Pair Bond Circuitry and Molecules (4)

Social Monogamy and Mate-Guarding (5)

Socially Monogamous Animals as a Model to Understand Jealousy (6)

Prairie Voles (7)

Prairie Voles as a Model to Understand the Evolution of Jealousy (10)

Materials and Methods (11)

Animals (11)

Pairing Procedure (12)

Behavioral Tests (13)

Pilot Experiment (13))

Choice Experiment (14)

Behavioral Coding (15)

Physiology (16)

Collection of Plasma and Tissue (16)

Sectioning (17)

Corticosterone Analysis (17)

Histology (18)

Immunohistochemistry (18)

Image Analysis (19)

Data Analysis (20)

Results (21)

Pilot Experiment (21)

Choice Experiment (27)

Discussion (28)

Limitations (33)

Implication (34)

Tables and Figures (14-28)

Figure 1. Setup of the behavioral test in the pilot experiment (14)

Figure 2. Setup of the behavioral test in the choice experiment (15)

Figure 3. Measurement of investigative behaviors (16)

Figure 4. Measure of FOS activation using DeepFLaSH (20)

Figure 5. Duration of investigative behaviors in pilot experiment (23)

Figure 6. FOS activation in pilot experiment (24)

Figure 7. Corticosterone levels in pilot experiment (26)

Figure 8. Duration of investigative behaviors in choice experiment (28)

References (36)

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