Connections within young children's brains strengthen while they sleep

A study shows that as children under five years old sleep, the connections between the left and right halves of their brain strengthen showing the importance of sleep in young children.

As young children sleep, the connections between the right and left sides of their brains strengthen, according to a small new study.

Researchers measured the brain activity of eight children while they slept at ages 2, 3 and 5 years. They found that connections in the brain generally became stronger during sleep as the children aged.

The strength of the connections between the left and right sides of the brain increase as much as 20 percent over a night's sleep, according to the study, which was published online Nov. 12 in the journal Brain Sciences.

"There are strong indications that sleep and brain maturation are closely related, but at this time, it is not known how sleep leads to changes in brain structure," study leader Salome Kurth, a postdoctoral researcher at the University of Colorado, Boulder, said in a university news release.

How sleep disruption during childhood may affect brain development and behavior will be examined in future studies.

"I believe inadequate sleep in childhood may affect the maturation of the brain related to the emergence of developmental or mood disorders," Kurth said.

It was already known that the brain changes drastically during early childhood. New connections are formed, others disappear and a fatty layer called "myelin" forms around nerve fibers in the brain. The growth of myelin strengthens the connections by speeding up the transfer of information, according to background information included in the news release.

Maturation of nerve fibers improves children's skills in areas such as language, attention and impulse control. But it hasn't been clear what role sleep plays in the development of such brain connections.

Read more here

Link Between Childhood Trauma and Neurological Changes

Recently, a link has been discovered between trauma during early childhood and neurological changes, a link that has been previously difficult to find.

It is well known that violent adults often have a history of childhood psychological trauma. Some of these individuals exhibit very real, physical alterations in a part of the brain called the orbitofrontal cortex. Yet a direct link between such early trauma and neurological changes has been difficult to find, until now.

Publishing in the January 15 edition of Translational Psychiatry, EPFL Professor Carmen Sandi and team demonstrate for the first time a correlation between psychological trauma in pre-adolescent rats and neurological changes similar to those found in violent humans.

"This research shows that people exposed to trauma in childhood don't only suffer psychologically, but their brain also gets altered," explains Sandi, Head of EPFL's Laboratory of Behavioral Genetics, Director of the Brain Mind Institute, and a member of the National Centers for Competence in Research SYNAPSY. "This adds an additional dimension to the consequences of abuse, and obviously has scientific, therapeutic and social implications."

The researchers were able to unravel the biological foundations of violence using a cohort of male rats exposed to psychologically stressful situations when young. After observing that these experiences led to aggressive behavior when the rats reached adulthood, they examined what was happening in the animals' brains to see if the traumatic period had left a lasting mark.

"In a challenging social situation, the orbitofrontal cortex of a healthy individual is activated in order to inhibit aggressive impulses and to maintain normal interactions," explains Sandi. "But in the rats we studied, we noticed that there was very little activation of the orbitofrontal cortex. This, in turn, reduces their ability to moderate their negative impulses. This reduced activation is accompanied by the overactivation of the amygdala, a region of the brain that's involved in emotional reactions." Other researchers who have studied the brains of violent human individuals have observed the same deficit in orbitofrontal activation and the same corresponding reduced inhibition of aggressive impulses. "It's remarkable; we didn't expect to find this level of similarity," says Sandi.

The scientists also measured changes in the expression of certain genes in the brain. They focused on genes known to be involved in aggressive behavior for which there are polymorphisms (genetic variants) that predispose carriers to an aggressive attitude, and they looked at whether the psychological stress experienced by the rats caused a modification in the expression of these genes. "We found that the level of MAOA gene expression increased in the prefrontal cortex," says Sandi. This alteration was linked to an epigenetic change; in other words, the traumatic experience ended up causing a long-term modification of this gene's expression.

Finally, the researchers tested the efficacy of an MAOA gene inhibitor, in this case an anti-depressant, to see if it could reverse the rise in aggression induced by juvenile stress, which it did. Going forward, the team will explore treatments for reversing physical changes in the brain, and above all, attempt to shed light on whether some people are more vulnerable to being effected by trauma based on their genetic makeup.

"This research could also reveal the possible ability of antidepressants -- an ability that's increasingly being suspected -- to renew cerebral plasticity," says Sandi.

Read more here