Scratching Your Knee Keeps the Brain Busy

A simple way to confuse your brain is to cross your fingers and touch the tip of your nose with the insides of the crossed fingers.  It feels like you have two noses!  Simply crossing your hands can confuse your brain if you can’t see them.  Just scratching your right knee with your left hand keeps the brain really busy.

030401Scientists are now using functional magnetic resonance imaging to understand the way our brains process stimulation to the right hand when it lies to the left of the body.  As well, they are studying the way it’s different when we can see the hand, versus when we can’t.

This technique shows that actions we perform without effort, like reaching for a cup, actually require the brain to combine much information from different senses.  Visual information about the location of the cup, the awareness of your body position, even sound and tactile information about the feel of the object are all integrated in this simple action.

The brain behaves differently when our eyes are closed.  With the eyes closed, the position of the hand determines the focus of the brain activity in its right hemisphere.  With the eyes open processing shifts to the left hemisphere.  This shift from right to left hemisphere accounts for the much better performance when we can see our hand.

So next time you cross your arms, be thankful your brain is adept at integrating all the information, and can distinguish your right from your left.