Isolating mouse pups from their mothers early in development can reduce the insulation surrounding neurons of the brain, which leads to problems with memory and socialization, a study in Science reported last week (September 14). The study provides a molecular explanation for the cognitive deficits observed in children raised in orphanages where they are rarely touched.
“This is incredibly important data, because it gives us the neural mechanisms associated with the deleterious changes in the brain” that arise from neglect, Nathan Fox, a cognitive neuroscientist at the University of Maryland told Wired Science.
Researchers from Harvard University took mice that were 21 days old and kept them isolated from other mice for 1 month. Afterwards, they were put in cages with other mice that had been raised with others. Isolated mice spent less time interacting with others, and seemed content inspecting props in the cage. They also performed more poorly on memory tests.
Earlier studies had shown that human children raised in isolation or abusive conditions had less white matter in their prefrontal cortex—the part of the brain involved in memory, decision making, and social interactions. When the Harvard team looked at the brain cells of their isolated mice, they noticed that the myelin sheaths that insulate neurons and make them send and receive signals faster, were reduced in size. However, mice that were raised with other pups until 5 weeks of age, then put in isolation, did not show the same deficits, suggesting that myelin is formed during a critical early window in development.
(Hat tip ScienceNOW.)