The prefrontal cortex is involved in complex emotional and cognitive behavior. It is known that early social experiences may affect its myelination during development, but it is unclear whether this form of plasticity persists in the adult brain. Given that neuroimaging studies in human subjects support the concept of ongoing prefrontal cortex myelination until the third decade of life, this study investigated whether depriving adult mice of social contact would affect adult prefrontal cortex myelination. After 8 weeks of social isolation, no difference in locomotor activity between isolated mice and group-housed controls was observed. However, isolated mice spent significantly less time interacting with a conspecific mouse compared with group-housed peers, which is a mouse model of social withdrawal.

Prolonged social isolation of adult mice was also found to induce transcriptional and ultrastructural changes in oligodendrocytes of the prefrontal cortex and impaired adult myelination. Myelin thickness in the prefrontal cortex was reduced. However, social re-integration was sufficient to normalize behavioral and transcriptional changes.

The authors of this study point out that white matter abnormalities are known to occur in psychiatric disorders characterized by social withdrawal in response to stress. They also note that demyelinating disorders characterized by myelin loss show co-morbidity with depression.  The translational application of their findings supports the importance of maintaining a healthy lifestyle and socially stimulating environment, especially in pathologies characterized by lost or damaged myelin.

Liu J, Dietz K, DeLoyht JM, Pedre X, Kelkar D, Kaur J, Vialou V, Lobo MK, Dietz DM, Nestler EJ, Dupree J, Casaccia P: Impaired adult myelination in the prefrontal cortex of socially isolated mice. Nature Neuroscience (2012) doi:10.1038/nn.3263 [Epub ahead of print, November 11, 2012].

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