Stimulation of the semicircular canals can artificially control human walking and balance

Aug 07, 2006

By applying electrical currents across the heads of people while they walk, researchers have improved our understanding of how our vestibular system helps us maintain upright posture; at the same time, the researchers found that the stimulus could be applied in a way that allowed a person who was walking straight ahead to be steered by "remote control" without her balance being affected.

The findings are reported by Richard Fitzpatrick and Jane E. Butler of the Prince of Wales Medical Research Institute and the University of New South Wales, Australia, and Brian L. Day of University College London in the August 8th issue of Current Biology, published by Cell Press.

To investigate how the body's ability to sense head movements can contribute to balance control and guidance control--two critical aspects of bipedal locomotion--the researchers stimulated nerves that normally communicate signals from the so-called semicircular canals, structures that are part of the vestibular system that assists in orientation and balance. The researchers found that artificial stimulation of semiciruclar canal nerves afforded "remote control" that was accurate enough to keep subjects on pathways and avoiding obstacles while walking blindfolded through botanical gardens. The researchers also found that with a subject's head in another position, exactly the same stimulus could be used to disturb upright balance, causing the subject to lean in one direction or the other, but without having any effect on steering his walking.

Known as bipedalism, our habitual upright posture is unique in the animal kingdom and has arisen through specific complementary adaptations of the body and brain. It has been believed that the key to human balance has come from a precise sense of--and ability to align the body to--the direction of gravity.

However, the semicircular canals that the researchers stimulated to control walking and balance detect rotational movements of the head, not the direction of gravity. These findings therefore show that sensing movement is crucial for our upright posture.

The findings support interpretations made from fossil evidence of an evolutionary change in the development of the human semicircular canals. These evolutionary changes would allow for enhanced movement detection, and therefore also indicate that that controlled movement, rather than alignment to gravity, has been important for the development of modern human bipedalism.

This new work has important implications for understanding how the brain processes sensory signals.

According to the researchers, the findings indicate that from the single sensory organ that signals the movement of the head, the brain makes instant complex "mathematical" calculations to discard the parts not important to balance or steering, such as the movements we make when looking around, and then transforms the remaining signal into two components. One component is used to control steering, and the other to control balance. In a more practical view, this ability to produce illusions of movement, and then steer and balance the body by external control, leads the researchers to expect that stimulation techniques developed from the approach used in the new study will lead the way to diagnostic, therapeutic, and virtual-reality applications.

Source: Cell Press

Explore further: Mindfulness treatment as effective as CBT for depression and anxiety

add to favorites email to friend print save as pdf

Related Stories

Firmer footing for robots with smart walking sticks

Nov 25, 2014

Anyone who has ever watched a humanoid robot move around in the real world—an "unstructured environment," in research parlance—knows how hard it is for a machine to plan complex movements, balance on ...

Recommended for you

'Chatty' cells help build the brain

2 hours ago

The cerebral cortex, which controls higher processes such as perception, thought and cognition, is the most complex structure in the mammalian central nervous system. Although much is known about the intricate ...

Duality in the human genome

3 hours ago

Humans don't like being alone, and their genes are no different. Together we are stronger, and the two versions of a gene – one from each parent – need each other. Scientists at the Max Planck Institute ...

Real-time volume imaging of hearts

4 hours ago

A new ultrasound system from Siemens enables doctors to carry out heart examinations through the esophagus for the first time. The system supplies 3D images of the heart as well as additional real-time information ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.