August 15, 2013
Our Brain Senses A Fall Before Our Muscles React
April Flowers for redOrbit.com - Your Universe Online
When you stumble and fall, your brain catches on very quickly, but it feels like your muscles aren’t doing anything to stop it – and it always occurs in front of a million people, or at least that one person you want to impress the most.
A fall for a young person is merely embarrassing. For an elderly person, however, falling can be a life threatening situation. Approximately 80 percent of the elderly who break a hip die within a year.
A new study from the University of Michigan suggests the critical window of time between when the brain senses a fall and when the muscles respond may help explain why so many older people suffer these serious falls – which could add a great deal to prevention efforts.
The findings, reported in the Journal of Neurophysiology, revealed many areas of the brain sense and respond to a fall, but that happens well before the muscles react. Daniel Ferris, professor of Kinesiology, likened the study method to recording an orchestra with many microphones and then teasing out the sounds of specific instruments. The research team used the EEG to measure electrical activity in different regions of the brain.
"We're using an EEG in a way others don't, to look at what's going on inside the brain," said Ferris. "We were able to determine what parts of the brain first identify when you are losing your balance during walking."
Healthy young subjects walked on a balance beam mounted to a treadmill with electrodes attached to their scalps. To avoid injury, when a participant lost their balance and fell from the beam, they simply continued walking on the moving treadmill.
The research team used a method known as independent components analysis to separate and visualize the electrical activity in different regions of the brain. According to their findings, people sense the start of a fall much better with both feet on the ground. People aren’t as sure of their stability on one foot, but two grounded feet make it easier to determine where the ground is relative to the body.
The team was surprised to find so many regions of the brain activate during a fall. They also found it surprising the brain recognizes a loss of balance as quickly as it does.
The scientists suggest further studies that compare the elderly with younger subjects could help determine if the elderly sense falls too late. If this is the case, pharmaceuticals might help them regain their balance. If, instead, it is a simple motor problem such as muscles not responding properly, then strengthening exercises could help.
The Ferris lab is continuing research under the same grant, looking to separate sensory and motor contributions to brain activity during walking.