Wednesday, September 12, 2007

Balance enhancing ear implant

Pic: Della Santina holding multichannel vestibular prosthesis.

Scientists at the Vestibular Neuroengineering Laboratory at Johns Hopkins University are developing a vestibular prosthesis.

They have tested the concept on chincillas with some success. Usable human versions may still be years away, but the proof of concept is promising.

More from the John Hopkins University Gazette:
In its report in the June edition of the journal I.E.E.E. Transactions on Biomedical Engineering, the Johns Hopkins team showed that a matchbox-size prototype device, weighing less than three ounces, effectively mimics the workings of the inner ear's three semicircular canals by sensing head rotation and transmitting that information to the brain.
Adapting the design of cochlear implants...researchers constructed a circuit that could measure and transmit 3-D balance information to the brain through multiple electrodes connected to the vestibular nerve.
The device...consists of a head- mounted battery-operated box containing the sensors, which are positioned outside the head so that the sensors are parallel to the animal's actual semicircular canals, where head rotation is normally sensed. The sensors are connected to a microprocessor and up to eight electrodes surgically implanted in the inner ear and separately connected to nerve endings. Each electrode can act as one information channel.
Della Santina says that people disabled by loss of vestibular sensation often feel chronically off balance and lose the ability to keep the eyes steadily pointed at an object when they move their head, "seeing the world like the wobbly image on a shaky handheld video camera."
... this is the first implantable device made with multiple sensors and channels of processing that can measure and encode head rotation in all directions.
Each of the three sensors... can measure the speed of head rotation about one of three axes, or directional planes.

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