It’s unavoidable: breakdowns in brain connections slow down our physical response times as we age, a new study suggests.
This slower reactivity is associated with an age-related breakdown in the corpus callosum, a part of the brain that acts as a dam during one-sided motor activities to prevent unwanted connectivity, or cross-talk, between the two halves of the brain, said Rachael Seidler, associate professor in the University of Michigan School of Kinesiology and Department of Psychology, and lead study author.
At other times the corpus callosum acts at a bridge and cross-talk is helpful, such as in certain cognitive functions or two-sided motor skills.
The U-M study is the first known to show that this cross-talk happens even while older adults are at rest, said Seidler.
“Cross-talk is not a function of task difficulty, because we see these changes in the brain when people are not moving,”
In some diseases where the corpus callosum is very deteriorated, such as in people with multiple sclerosis, you can see “mirror movements” during one sided-motor tasks, where both sides move in concert because there is so much communication between the two hemispheres of the brain, Seidler said. These mirror movements also happen normally in very young children before the corpus callosum is fully developed.
“The more they recruited the other side of the brain, the slower they responded”
A previous study done by another group showed that doing aerobic training for three months helped to rebuild the corpus callosum, she said, which suggests that physical activity can help to counteract the effects of the age-related degeneration
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