Early Life Experiences and Social Development


I have strongly advocated the use of ethologically relevant housing and observational paradigms for the study of animal social behavior. I believe that is critical to provide development expectant socialization to laboratory animals if we wish to understand 'normal' brain development.

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Weaning Age I have shown that the age at which animals are weaned has significant effects on their social development. Usually in the laboratory, mice are removed from their mothers at day 21 postnatally. I have shown that mothers will nurse and lick/groom their offspring beyond this period up to day 28 postnatally. During this fourth week postpartum dams will actively wean offspring by pinning and mounting them in response to pups' nipple soliciations. The image to the left shows a 4 week old pup sucking from its mother. I have also shown that female dams that provide less licking/grooming to their pups in the first week postnatally are more likely to actively wean their pups sooner. Pups that are weaned earlier exhibit increased levels of juvenile social play behavior likely as a compensatory mechanism for receiving less tactile stimulation early in life. Later actively weaned offspring are faster to exhibit other social behaviors. I have also shown that early weaned female offspring are more likely to wean their own offspring earlier.

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Figure from Franks et al 2015 showing how low licking dams wean offspring earlier and those offspring engage earlier in social play.

Video showning mouse dam mounting and pinning 24 day old pup in response to nipple solicitation.

References

Curley JP, Jordan E, Swaney WT, Izraelit A, Kammel S & Champagne FA, 2009, The Meaning of Weaning: Influence of the Weaning Period on Behavioral Development in Mice, Developmental Neuroscience 31: 318-331.

Franks B, Champagne FA & Curley JP, 2015, Postnatal maternal care predicts divergent weaning strategies and the development of social behavior. Developmental Psychobiology 57(7):809-17.






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Communal Nesting In the wild over 90% of Mus musculus females will rear their offspring in communal nests. In the laboratory, the typical method of rearing is one dam with her litter. I have shown that rearing pups in large communal nests (three dams sharing litters) leads to profound changes in the maternal and social behavior of mouse offspring as well as the distribution of oxytocin and vasopressin receptors in several brain regions. Furthermore, these behavioral changes can be transmitted over generations through female offspring.

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Recently in collaboration with Igor Branchi, we have shown that male mouse pups reared in communal nests have increased social competency in that they are quicker to recognize their social status when tested in pairs as adults. This effect is only found for pups from older and younger litters who also receive higher levels of maternal care. Both forms of social enrichment (maternal care and peer socialization) appear to be necessary. Increased social competency is associated with higher protein levels of BDNF in the hippocampus, frontal cortex and hypothalamus.

Video showning three mouse dams communally rearing their ten day old pups.

References

Curley JP , Davidson S, Bateson P & Champagne FA, 2009, Social enrichment during postnatal development induces transgenerational effects on emotional and reproductive behavior in mice, Frontiers in Behavioral Neuroscience. 3(25): 1-14.

Branchi I, Curley JP, D’Andrea I, Cirulli F, Champagne FA & Alleva E, 2013, Early interactions with mother and peers independently build adult social skills and shape BDNF and oxytocin receptor brain levels, Psychoneuroendocrinology 38: 522-532.







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