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A Social Network Approach Reveals Associations between Mouse Social Dominance and Brain Gene Expression.

So N, Franks B, Lim S, Curley JP - PLoS ONE (2015)

Bottom Line: Though grooming ties between individuals were largely independent of other social networks, sniffing relationships were highly predictive of the directionality of agonistic relationships.Individual variation in dominance status was associated with brain gene expression, with more dominant individuals having higher levels of corticotropin releasing factor mRNA in the medial and central nuclei of the amygdala and the medial preoptic area of the hypothalamus, as well as higher levels of hippocampal glucocorticoid receptor and brain-derived neurotrophic factor mRNA.This study demonstrates the potential and significance of combining complex social housing and intensive behavioral characterization of group-living animals with the utilization of novel statistical methods to further our understanding of the neurobiological basis of social behavior at the individual, relationship and group levels.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, Columbia University, New York, NY 10027, United States of America; Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY 10025, United States of America.

ABSTRACT
Modelling complex social behavior in the laboratory is challenging and requires analyses of dyadic interactions occurring over time in a physically and socially complex environment. In the current study, we approached the analyses of complex social interactions in group-housed male CD1 mice living in a large vivarium. Intensive observations of social interactions during a 3-week period indicated that male mice form a highly linear and steep dominance hierarchy that is maintained by fighting and chasing behaviors. Individual animals were classified as dominant, sub-dominant or subordinate according to their David's Scores and I& SI ranking. Using a novel dynamic temporal Glicko rating method, we ascertained that the dominance hierarchy was stable across time. Using social network analyses, we characterized the behavior of individuals within 66 unique relationships in the social group. We identified two individual network metrics, Kleinberg's Hub Centrality and Bonacich's Power Centrality, as accurate predictors of individual dominance and power. Comparing across behaviors, we establish that agonistic, grooming and sniffing social networks possess their own distinctive characteristics in terms of density, average path length, reciprocity out-degree centralization and out-closeness centralization. Though grooming ties between individuals were largely independent of other social networks, sniffing relationships were highly predictive of the directionality of agonistic relationships. Individual variation in dominance status was associated with brain gene expression, with more dominant individuals having higher levels of corticotropin releasing factor mRNA in the medial and central nuclei of the amygdala and the medial preoptic area of the hypothalamus, as well as higher levels of hippocampal glucocorticoid receptor and brain-derived neurotrophic factor mRNA. This study demonstrates the potential and significance of combining complex social housing and intensive behavioral characterization of group-living animals with the utilization of novel statistical methods to further our understanding of the neurobiological basis of social behavior at the individual, relationship and group levels.

No MeSH data available.


The mouse vivarium.
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pone.0134509.g001: The mouse vivarium.

Mentions: 12 male outbred CD1 mice aged 6 weeks were purchased from Charles River and housed in groups of 4 for 3 weeks prior to testing. All mice were individually and uniquely marked by dying their fur with a blue, nontoxic, non-hazardous marker (Stoelting Co.). These marks remain for up to 12 weeks and only require one application, thus enabling each animal to be uniquely identified throughout the study. All animals were also given a unique and random two-letter code for identification purposes. At 9 weeks of age, all mice were weighed and placed into a large custom built mouse vivarium (length 150cm, height 80cm, width 80cm; Mid-Atlantic) (Fig 1). The vivarium consisted of three sides of Plexiglas with sliding front doors and a metal backboard containing multiple holes for air circulation. The vivarium was split into two sides, each with two shelves. Standard food chow and water was provided ad libitum at the top shelf via cage lids that protruded through the vivarium roof. Animals could access each shelf via the backboard or via ramps and tunnels that connected each shelf and side. Multiple enrichment objects such as plastic igloos and wooden blocks were also provided. Floors of each shelf and side were covered with pine shaving bedding. The animals were kept in the same room throughout the study, with white lights (light cycle) coming on at 2400 hours and red lights (dark cycle) coming on at 1200 hours, at a constant temperature (21–24°C) and humidity (30–50%). Mice were housed in the Department of Psychology at Columbia University. All procedures were conducted with approval from the Columbia University Institutional Animal Care and Use Committee (ICAUC).


A Social Network Approach Reveals Associations between Mouse Social Dominance and Brain Gene Expression.

So N, Franks B, Lim S, Curley JP - PLoS ONE (2015)

The mouse vivarium.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520683&req=5

pone.0134509.g001: The mouse vivarium.
Mentions: 12 male outbred CD1 mice aged 6 weeks were purchased from Charles River and housed in groups of 4 for 3 weeks prior to testing. All mice were individually and uniquely marked by dying their fur with a blue, nontoxic, non-hazardous marker (Stoelting Co.). These marks remain for up to 12 weeks and only require one application, thus enabling each animal to be uniquely identified throughout the study. All animals were also given a unique and random two-letter code for identification purposes. At 9 weeks of age, all mice were weighed and placed into a large custom built mouse vivarium (length 150cm, height 80cm, width 80cm; Mid-Atlantic) (Fig 1). The vivarium consisted of three sides of Plexiglas with sliding front doors and a metal backboard containing multiple holes for air circulation. The vivarium was split into two sides, each with two shelves. Standard food chow and water was provided ad libitum at the top shelf via cage lids that protruded through the vivarium roof. Animals could access each shelf via the backboard or via ramps and tunnels that connected each shelf and side. Multiple enrichment objects such as plastic igloos and wooden blocks were also provided. Floors of each shelf and side were covered with pine shaving bedding. The animals were kept in the same room throughout the study, with white lights (light cycle) coming on at 2400 hours and red lights (dark cycle) coming on at 1200 hours, at a constant temperature (21–24°C) and humidity (30–50%). Mice were housed in the Department of Psychology at Columbia University. All procedures were conducted with approval from the Columbia University Institutional Animal Care and Use Committee (ICAUC).

Bottom Line: Though grooming ties between individuals were largely independent of other social networks, sniffing relationships were highly predictive of the directionality of agonistic relationships.Individual variation in dominance status was associated with brain gene expression, with more dominant individuals having higher levels of corticotropin releasing factor mRNA in the medial and central nuclei of the amygdala and the medial preoptic area of the hypothalamus, as well as higher levels of hippocampal glucocorticoid receptor and brain-derived neurotrophic factor mRNA.This study demonstrates the potential and significance of combining complex social housing and intensive behavioral characterization of group-living animals with the utilization of novel statistical methods to further our understanding of the neurobiological basis of social behavior at the individual, relationship and group levels.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, Columbia University, New York, NY 10027, United States of America; Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY 10025, United States of America.

ABSTRACT
Modelling complex social behavior in the laboratory is challenging and requires analyses of dyadic interactions occurring over time in a physically and socially complex environment. In the current study, we approached the analyses of complex social interactions in group-housed male CD1 mice living in a large vivarium. Intensive observations of social interactions during a 3-week period indicated that male mice form a highly linear and steep dominance hierarchy that is maintained by fighting and chasing behaviors. Individual animals were classified as dominant, sub-dominant or subordinate according to their David's Scores and I& SI ranking. Using a novel dynamic temporal Glicko rating method, we ascertained that the dominance hierarchy was stable across time. Using social network analyses, we characterized the behavior of individuals within 66 unique relationships in the social group. We identified two individual network metrics, Kleinberg's Hub Centrality and Bonacich's Power Centrality, as accurate predictors of individual dominance and power. Comparing across behaviors, we establish that agonistic, grooming and sniffing social networks possess their own distinctive characteristics in terms of density, average path length, reciprocity out-degree centralization and out-closeness centralization. Though grooming ties between individuals were largely independent of other social networks, sniffing relationships were highly predictive of the directionality of agonistic relationships. Individual variation in dominance status was associated with brain gene expression, with more dominant individuals having higher levels of corticotropin releasing factor mRNA in the medial and central nuclei of the amygdala and the medial preoptic area of the hypothalamus, as well as higher levels of hippocampal glucocorticoid receptor and brain-derived neurotrophic factor mRNA. This study demonstrates the potential and significance of combining complex social housing and intensive behavioral characterization of group-living animals with the utilization of novel statistical methods to further our understanding of the neurobiological basis of social behavior at the individual, relationship and group levels.

No MeSH data available.