Balance and Balance Disorders

Balance As a "Sixth Sense": Integration of Sensory Input

A healthy person usually takes his or her sense of balance for granted. Most people don't find it difficult to walk across a gravel driveway, transition from walking on the sidewalk to the grass, or get out of bed in the middle of the night without stumbling or feeling unsteady. The ability to balance depends on:

Integration of Sensory Input

All of the sensory input concerning balance, from the eyes, from the muscles and joints, and from the two sides of the vestibular system, is sent to the brain stem, where it is sorted out and integrated with contributions from other parts of the brain. 

Contributions from other parts of the brain
The brain stem also receives input from two other areas of the brain—the cerebellum, which functions as the coordination center, and the cerebral cortex, which functions in thinking and memory. As the brain stem is integrating all the input it receives concerning balance, the cerebellum may contribute information about automatic movements that have been learned through constant practice, e.g. adjustments in balance needed to serve a tennis ball. The cerebral cortex contributes previously learned information, e.g., that icy sidewalks are slippery and require a person to walk on them with a different pattern of movement pattern in order to maintain balance.

Conflicting sensory input
There are times that the sensory input that we receive from one of the sources conflicts with the input from the other sources. For example, when standing next to a bus that is pulling away from the curb, your visual input from the large rolling bus may indicate that you are moving. You may lean forward a little to compensate for that sensation, or feel dizzy. But your muscles and joints send input that you are not moving, and other visual input finally indicates that other objects are stationary, and a correction is made.

As integration of all the sensory input takes place, the brain stem sends out impulses along motor-nerve fibers that begin in the brain stem and end in the muscles. These muscles make your head and neck, your eyes, your legs, and the rest of your body move and allow you to maintain your balance and have clear vision while you are moving.

Source and Copyrights: VEDA

[Homepage] [Disclaimer/Privacy/Copyrights] [Sitemap]

© Copyrights PakMed Biomedical Solutions

Optimized for Java-script enabled Microsoft Internet Explorer 6, at screen resolution of 800 by 600 pixels.

Microsoft and the Office logo are trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries.