Lewis Richard F, Gong Wangsong, Ramsey Mitchell, Minor Lloyd, Boyle Richard, Merfeld Daniel M
Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, USA.
J Vestib Res. 2002;12(2-3):87-94.
We have developed and tested a prosthetic semicircular canal that senses angular head velocity and uses this information to modulate the rate of current pulses applied to the vestibular nerve via a stimulating electrode. In one squirrel monkey, the lateral canals were plugged bilaterally and the prosthesis was secured to the animal's head with the angular velocity sensor parallel to the axis of the lateral canals. In the first experiment, the stimulating electrode was placed near the ampullary nerve of one lateral canal. Over a period of two weeks, the gain of the horizontal VOR during yaw axis rotation gradually increased, although the response magnitude remained relatively small. In the second experiment, the stimulating electrode was placed near the ampullary nerve of the posterior canal, but the orientation of the velocity sensor remained parallel to the axis of the lateral canals. Over a one-week period, the axis of the VOR response gradually shifted towards alignment with the (yaw) axis of head rotation. Chronic patterned stimulation of the eighth nerve can therefore provide adequate information to the brain to generate a measurable VOR response, and this can occur even if the prosthetic yaw rotation cue is provided via a branch of the VIIIth nerve that doesn't normally carry yaw rotational cues. The results provided by this pilot study suggest that it may be feasible to study central adaptation by chronically modifying the afferent vestibular cue with a prosthetic semicircular canal.
我们研发并测试了一种人工半规管，它能感知头部角向速度，并利用该信息通过刺激电极来调节施加到前庭神经的电流脉冲频率。在一只松鼠猴身上，双侧外侧半规管被堵塞，人工半规管固定在动物头部，角速度传感器与外侧半规管的轴线平行。在第一个实验中，刺激电极放置在一侧外侧半规管的壶腹神经附近。在两周的时间里，偏航轴旋转期间水平前庭眼反射（VOR）的增益逐渐增加，尽管反应幅度仍然相对较小。在第二个实验中，刺激电极放置在后半规管的壶腹神经附近，但速度传感器的方向仍与外侧半规管的轴线平行。在一周的时间里，VOR反应的轴线逐渐转向与头部旋转的（偏航）轴对齐。因此，对第八神经进行慢性模式刺激能够向大脑提供足够的信息以产生可测量的VOR反应，即便人工偏航旋转线索是通过第八神经的一个通常不携带偏航旋转线索的分支提供的，这种情况也会发生。这项初步研究的结果表明，通过人工半规管长期改变传入前庭线索来研究中枢适应性可能是可行的。
