Closing an open-loop control system: vestibular substitution through the tongue.
The human postural coordination mechanism is an example of a complex closed-loop control system based on multisensory integration [9,10,13,14]. In models of this process, sensory data from vestibular, visual, tactile and proprioceptive systems are integrated as linearly additive inputs that drive multiple sensory-motor loops to provide effective coordination of body movement, posture and alignment [5-8, 10, 11]. In the absence of normal vestibular (such as from a toxic drug reaction) and other inputs, unstable posture occurs. This instability may be the result of noise in a functionally open-loop control system [9]. Nonetheless, after sensory loss the brain can utilize tactile information from a sensory substitution system for functional compensation [1-4, 12]. Here we have demonstrated that head-body postural coordination can be restored by means of vestibular substitution using a head-mounted accelerometer and a brain-machine interface that employs a unique pattern of electrotactile stimulation on the tongue. Moreover, postural stability persists for a period of time after removing the vestibular substitution, after which the open-loop instability reappears.
Tyler
Mitchell
M
Wicab, Inc, 3510 W. Beltline Hwy, Middleton, WI 53562, USA. metyler1@facstaff.wisc.edu
Danilov
Yuri
Y
Bach-Y-Rita
Paul
P
D000054:Acceleration; D000328:Adult; D001921:Brain / Q000503:physiopathology; D004558:Electric Stimulation; D005260:Female; D006257:Head / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity; D011187:Posture; D012682:Sensory Aids; D014059:Tongue / Q000503:physiopathology*; D014110:Touch; D015837:Vestibular Diseases / Q000503:physiopathology*