FIGURE 1.

Schematics of the elements constituting a vestibular prosthesis. The input to the prosthetic device is in the form of angular and linear accelerations produced by head movements, within the gravitational field. Sensors are constituted by accelerometers that respond to linear accelerations and gyroscopes which respond to angular accelerations, thus forming two flows of activity to be processed separately. The sensors are in the three spatial planes. The output of the sensors is a voltage, which feeds the processing unit. This unit converts the input voltage in a stimulation pattern defined by a transfer function adequate and differentiated for the linear accelerations-related input and for the angular accelerations input. The processor and coding unit output feeds a signal conditioning unit that converts the stimulation pattern in a current to be applied to the otolithic afferent neurons in one case and to the three semicircular canals in the other case.