Patent Description:
The ability to maintain spatial orientation and balance is the result of an elaborate synchronization of neural inputs from the vestibular, visual, and proprioceptive systems. When there is a mismatch among these signals or when input patterns from different senses do not correspond to stored expected sensory patterns, spatial disorientation may occur. The two primary conflicts occur between the visual and vestibular senses (i.e., intersensory conflict) and within the vestibular sense between the semicircular canals and otoliths (i.e., intrasensory conflict). Secondary conflict, however, may come from proprioceptive inputs that fail to synchronize with other sensory cues, particularly visual and peripheral proprioceptors connected to the vestibular system through vestibulospinal pathways. This creates the sensation commonly known as Motion Sickness. It includes a range of symptoms, from nausea and salivation to a sensation of warmth, tiredness, and other cognitive symptoms. In addition, sensory conflicts remain one of the most persistent issues facing advanced flight simulation development. Flight simulators have been shown to improve training effectiveness with considerably lower cost and risk than actual flight training. The capability to use simulation in training brings advantages in acquisition of skill sets, development of competencies, the reduction of errors in real environments, and decreased costs. The simulation environment, however, imposes limitations in matching real world sensory experiences. These limitations may manifest in the form of simulator-induced motion sickness, also known as simulator sickness (SS). SS is a variant of motion sickness resulting from exposure to simulated environments such as flight simulators, driving simulators and similar virtual, immersive environments. Whereas motion sickness refers to the adverse consequences of exposure to environments that physically put an individual in motion, SS is mainly the result of technological limitations in simulating dynamic environments that create a conflict in the body's self-motion perception sensors. Because of the wide variety of these symptoms, such as nausea, oculomotor disorders, disorientation, and the like, SS has also been described as "polygenic" since several factors have been identified including age, gender, simulator features, e.g., lag and field of view (FOV), and factors associated with the task performed, e.g., duration and degree of control. The theory of sensory conflict, also known as the sensory rearrangement or neural mismatch theory, indicates that sickness occurs when the pattern of inputs from different senses and within a single sensory modality do not correspond to the stored patterns of such inputs based on past experience, as a result of both cognitive and perceptual discrepancy. When SS symptoms develop, the value of the training experience and data derived during the experience may be compromised and in the most extreme cases results in negative transfer-of-training. Moreover, since symptoms may persist or recur spontaneously up to one day after exposure, various training centers routinely ground pilots for <NUM> to <NUM> hours after simulator time. These factors can lower the acceptance and overall utility of simulator enhanced learning. Conventional preventative pharmacological agents commonly used for motion sickness are typically ineffective to prevent SS and may be commonly associated with significant side effects after the simulated sessions including drowsiness and fatigue. Thus, simulator design may have a significant role in decreasing the incidence of SS. However, even with technological advances, imperfections including optical deficiencies, image scale factor magnifications, system time delays, limited field of view (FOV) displays head tracker inaccuracies, and the like, still remain unsolved limitations which contribute to SS.

<CIT>teaches systems and techniques for stimulating motion to a human subject alleviating motion sickness and directional cueing related to the vestibular system with coupling of galvanic vestibular stimulation GVS which relies on voltage and current unequally at two different points on a subject's head to cause a change in a vestibular response. <CIT> teaches an implantable nerve stimulation device sensor system. The nerve stimulation system includes an electrode array with electrodes that are invasively, surgically implanted in the human subject. <CIT> teaches and discloses utilizing direct electrical current and utilizes a fixed reference voltage. Chinese Publ. No. <CIT> teaches and discloses a complex device with gears, pendulums, double pole, single throw power switch and a light source which utilizes the swing of the hull of a boat to change intensity and a resistance which changes magnitude and current. Korean Publ. No. <CIT> relies on a left and right movement input value provided by a virtual reality device which is larger than a reference value to indicate predetermined left and right abrupt rotational sense such that a pair of alternating current stimuluses may be applied. <CIT> also discloses a stimulation system known from the prior art.

Thus there is a need to mitigate motion sickness and/or SS by reducing or eliminating the mismatch between sensory cues inputs expected by a human subject and improve simulation based training.

In one aspect, a system for suppressing vestibular activity of a human subject, the system is featured. The system includes an electronics module configured to generate one or more electrical stimulation signals. A plurality of electrodes each placed proximate a predetermined location on a head of a human subject is configured to deliver the one or more electrical stimulation signals to the predetermined location to suppress vestibular activity of the human subject.

In one embodiment, the plurality of electrodes may be bi-laterally placed on opposing sides of the head. The predetermined location may include a mastoid process, the ear, or a temporal bone of the human subject. The one or more electrical stimulation signals may include one or more direct current (DC) signals. The one or more stimulation signals may include one or more DC signals each with an imposed carrier wave. The one or more stimulation signals may include one or more alternating current (AC) signals. The one or more electrical stimulation signals may be configured to hyperpolarize and/or depolarized cells located at each predetermined location to create a desired induced perception of motion. The plurality of electrodes may be configured to deliver electrical stimulation to suppress the vestibular system of the human subject to actual motion such that perception of motion of the human subject is reduced. The suppression of the vestibular system of the human subject to actual motion may decrease motion sickness that may arise from motion sensed by the human subject. The plurality of electrodes may include a first pair of electrodes placed on one side of the head of the human subject at the predetermined location, another pair of electrodes placed on an opposite side of the head of the human subject at the predetermined location, and a ground electrode placed on the head or neck of the human subject. Each pair of electrodes may include an electrode configured as positive electrode and an electrode configured as a negative electrode. The one or more electrical stimulation signals may be configured as one or more DC signals applied to each positive and negative electrode such that the one or more DC signals are transmitted from the positive electrode located at high predetermined location on the head of the human subject to the negative electrode located at a low location on the head of the human subject to suppress vestibular activity. The high predetermined location may include a high location on a mastoid process of the human subject and the low location includes a low location on mastoid process of the human subject. The one or more electrical stimulation signals may be configured as one or more DC signals each imposed carrier wave applied in phase to each positive and negative electrode such that the one or more DC signals with the imposed carrier waves are transmitted from the positive electrode at a high predetermined location to the negative electrode at a low predetermined location to suppress vestibular activity. The one or more electrical stimulation signals may be configured as one or more DC signals each imposed carrier wave applied temporally offset to each positive and negative electrode such that the one or more DC signals with the imposed carrier waves are transmitted from the positive electrode at a high predetermined location on one side of the head to the negative electrode at a low predetermined location on an opposite side of the head to suppress vestibular activity. The high predetermined location may include a high location on mastoid process and the low predetermined location includes a low location on mastoid process of the human subject. The plurality of electrodes may include one electrode placed on one side of the head of the human subject at the predetermined location and another electrode is placed on an opposite side of the head of the human subject at the predetermined location. The one or more electrical stimulation signals may be configured as one or more AC signals applied to the electrode placed on one side of the head and the electrode placed on one the opposite side of the head such that the one or more AC signals are transmitted back and forth from one electrode at its maximum current at the predetermined location on one side of the head to the another electrode at its maximum negative current at the predetermined location on an opposite side of the head of the human subject to suppress vestibular activity.

As disclosed herein, all examples of methods for suppressing vestibular activity of a human subject are for use with the system for suppressing vestibular activity and are of explanatory nature.

In another aspect, a method for suppressing vestibular activity of a human subject is featured. The method includes generating one or more electrical stimulation signals, and delivering the one or more electrical stimulation signals to a plurality of electrodes each placed proximate a predetermined location on a head of the human subject such that the one or more electrical stimulation signals suppress vestibular activity of the human subject.

In one embodiment, the method may include bilaterally placing the electrodes on opposing sides of the head of the human subject at the predetermined location. The one or more electrical stimulation signals may hyperpolarize and/or may depolarize cells located at each predetermined location to create a desired induced perception of motion. The method may include delivering electrical stimulation to suppress the vestibular system of the human subject to actual motion such that perception of motion of the human subject is reduced. The suppression of the vestibular system of the human subject to actual motion may decrease motion sickness that may arise from motion sensed by the human subject. The one or more electrical stimulation signals may include one or more direct current (DC) signals. The one or more stimulation signals may include one or more DC signals each with an imposed carrier wave. The one or more stimulation signals may include one or more alternating current (AC) signals. The one more electrical stimulation signals may include one or more DC signals transmitted from a positive electrode at a high predetermined location on one side of the head to the negative electrode at a low predetermined location on an opposite side of the head to suppress vestibular activity. The one more electrical stimulation signals may include one or more DC signals with the imposed carrier waves transmitted in phase from a positive electrode at a high predetermined location on one side of the head to the negative electrode at a low predetermined location on an opposite side of the head to suppress vestibular activity. The one more electrical stimulation signals may include one or more DC signals with the imposed carrier waves transmitted temporally offset from a positive electrode at a high predetermined location on one side of the head to the negative electrode at a low predetermined location on an opposite side of the head to suppress vestibular activity. The one more electrical stimulation signals may include one or more AC signals transmitted from an electrode on one side of the head at the determined location to an electrode on an opposite side of the head to suppress vestibular activity.

Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:.

The present invention is set out in the appended claims and pertains to a system for suppressing vestibular activity of a human subject.

There is shown in <FIG> one embodiment for system <NUM> and the method thereof for suppressing vestibular activity of a human subject. System <NUM> includes electronics module <NUM> configured to generate one or more stimulation signals which are applied to electrodes at predetermined locations of head <NUM> of the human subject to suppress vestibular activity as will be discussed in detail below. <FIG> shows examples of electronics module <NUM> which is capable of generating the one or more electrical stimulation signals, e.g. up to about <NUM> mA in a DC mode or an AC mode with a frequency between about <NUM> and <NUM> using frequency control <NUM> and amplitude control <NUM>. Electronics module <NUM> also preferably includes display <NUM> which displays the current and/or voltage of the one or more stimulation signals. In one design, electronics module <NUM> may be operated with batteries, e.g., <NUM> AA batteries indicated at <NUM>. Electronics module <NUM> also preferably includes electronics board <NUM> which is coupled to frequency control <NUM>, amplitude <NUM>, display <NUM>, and connectors <NUM>. Electronics board <NUM> is configured to generate the one or more electrical stimulation signals. <FIG> and <FIG> show in further detail examples of electronic circuitry <NUM>, <NUM>, respectively, incorporated into electronics board <NUM> of electronics module <NUM>, <FIG> and <FIG>, which may be used to generate the one or more electrical stimulation signals to suppress vestibular activity.

System <NUM>, <FIG>, also includes a plurality of electrodes each placed proximate a predetermined location on head <NUM> of the human subject configured to deliver the one or more electrical stimulation signals to the predetermined location on head <NUM> to suppress vestibular activity. In the example shown in <FIG>, system <NUM> includes plurality of electrodes <NUM> placed proximate a predetermined on one side of head <NUM> and plurality of electrodes <NUM> bilaterally placed proximate a predetermined location on an opposite sided of head <NUM> as shown, e.g., proximate the mastoid process <NUM>, <FIG>, and preferably within the area indicated at <NUM> which is located directly behind the external ear as shown. In other examples, the predetermined location on each side of head <NUM> may the temporal bone, indicated at <NUM>.

<FIG> shows exemplary electrodes which may be utilized (available from MFI Medical Equipment San Diego, CA) which are preferably coupled to connectors <NUM>, <FIG>.

In one example, one of the electrodes of the plurality of electrodes <NUM>, <FIG>, e.g., electrode <NUM>, may be configured as a positive electrode by connecting it to contact <NUM> which outputs positive DC or AC current generated by electronics module <NUM>. The other of plurality of electrodes <NUM>, <FIG>, e.g. electrode <NUM>, may be configured as a negative electrode by connecting it to contact <NUM> which outputs negative DC or AC current generated by electronics module <NUM>. Similarly, one of the electrodes of the plurality of electrodes <NUM>, e.g., electrode <NUM>, may be configured as a positive electrode by connecting it to contact <NUM> which outputs positive DC or AC current or voltage generated by electronics module <NUM> and the other of the plurality of electrodes <NUM>, e.g., electrode <NUM>, may be configured as a negative electrode by connecting it to negative contact <NUM> which outputs negative DC or AC current or voltage generated by electronics module <NUM>. Preferably, system <NUM> includes ground electrode <NUM> preferably placed proximate the nape of the neck as shown coupled to ground contact <NUM>.

The one or more electrical stimulation signals generated by electronics module <NUM> to electrodes <NUM>, <NUM> on one side of head <NUM> at the predetermined location and the one or more electrical stimulation signals applied to electrodes <NUM> and <NUM> at the predetermined location on an opposite side of head <NUM> of the human subject suppresses vestibular activity.

Preferably, the vestibular system of the human subject is suppressed to actual motion by system <NUM> and the method thereof such that the perception of motion of the human subject is reduced. Suppression of the vestibular system of the human subject to actual motion preferably decreases motion sickness and/or SS that may arise from motion sensed by the human subject. By suppressing vestibular activity, system <NUM> and the method thereof may mitigate motion sickness and/or SS by reducing or eliminating the mismatch between sensory cues inputs expected by a human subject and improve simulation based training.

The one or more electrical stimulation signals generated by electronics module <NUM> and delivered by electrodes <NUM>, <NUM> and <NUM>, <NUM> preferably hyperpolarize and/or depolarize cells proximate each predetermined location on head <NUM> as discussed above to create a desired induced perception of motion. System <NUM> and the method thereof mimics the polarization of the cells caused by motion with the application of small amounts of external electrical stimulation by the one or more electrical stimulation signals. By judicious application of the one or more electrical stimulation signals at appropriate external predetermined locations, the cells on each side of head <NUM> are preferably hyperpolarized and/or depolarized thereby using their natural response to create the desired signals. Unlike conventional systems and methods which may rely on swamping the signals sent the brain, system <NUM> and the method thereof works with the healthy vestibular system of the human subject to create a transient signal associated with acceleration of the head. Upon cessation of stimulation, the cells repolarize to their "at rest" condition within a few pulses, requiring less than a second to return to their pre-stimulation condition.

In one example, the one or more electrical stimulation signals stimulation signals generated by electronics module <NUM>, <FIG>, to suppress vestibular activity may include one or more direct current (DC) signals, one or more DC signals with an imposed carrier waves or one or more alternating current (AC) signals.

For example, electronics module <NUM>, <FIG>, where like parts have been given like numbers, may generate one or more electrical stimulation signals to suppress vestibular activity configured as positive DC signal <NUM> which is applied electrode <NUM> preferably located at an upper mastoid location of the head <NUM> as shown, e.g., at location <NUM>, <FIG> of area <NUM>. Electronics module <NUM> may also generate negative DC signal <NUM> which is applied to electrode <NUM> preferably located at a lower mastoid position on the head <NUM> as shown, e.g., at location <NUM> of area <NUM>. The one or more electrical stimulation signals in this example are transmitted from the upper mastoid location of the left side of head <NUM> to lower mastoid position on head <NUM> as shown by arrow <NUM> to suppress vestibular activity.

Similarly, electronics module <NUM> may generate one or more electrical stimulation signals to suppress vestibular activity configured as positive DC signal <NUM> which is applied electrode <NUM> preferably located at an upper mastoid location of the head <NUM>, as discussed above. Electronics module <NUM> may also generate negative DC signal <NUM> which is applied to electrode <NUM> located at a lower mastoid position on the head <NUM> as shown, e.g., as discussed above. The one or more electrical stimulation signals in this example are transmitted from the upper mastoid location of the head <NUM> to lower mastoid position on the head, as shown by arrow <NUM>, to suppress vestibular activity.

Electronics module <NUM>, <FIG>, where like parts have been given like numbers, may generate one or more electrical stimulation signals to suppress vestibular activity configured as DC signal <NUM> with imposed positive carrier wave <NUM> which is applied electrode <NUM> preferably located at an upper mastoid location of the head <NUM> as shown, similarly as discussed above. Imposed carrier wave <NUM> modulates the current applied to electrode <NUM> between <NUM> amps, indicated at <NUM>, and the maximum positive current, indicated at <NUM>. Electronics module <NUM> may also generate DC signal <NUM> with imposed negative carrier wave <NUM> which is applied to electrode <NUM> located at a lower mastoid position on the head <NUM> as shown, similar as discussed above. Imposed negative carrier wave <NUM> modulates the current applied to electrode <NUM> between <NUM> amps, indicated at <NUM>, and the maximum negative current, indicated at <NUM>. In this example, imposed carrier waves <NUM> and <NUM> are preferably in phase such that the one or more electrical stimulation signals are transmitted from electrode <NUM> to electrode <NUM>, as shown by arrow <NUM>, to suppress vestibular activity.

Similarly, electronics module <NUM>, <FIG>, may generate one or more electrical stimulation signals to suppress vestibular activity configured as configured as DC signal <NUM> with imposed positive carrier wave <NUM> which is applied electrode <NUM> preferably located at an upper mastoid location of the head <NUM> as shown. Imposed positive carrier wave <NUM> preferably modulates the current applied to electrode <NUM> between <NUM> amps, indicated at <NUM>, and the maximum positive current, indicated at <NUM>. Electronics module <NUM>, <FIG>, may also generate DC signal <NUM> with imposed negative carrier wave <NUM> which is applied to electrode <NUM> located at a lower mastoid position on the head <NUM> as shown, as discussed above. Imposed negative carrier wave <NUM> modulates the current applied to electrode <NUM> between <NUM> amps, indicated at <NUM>, and the maximum negative current, indicated at <NUM>. In this example, carrier waves <NUM> and <NUM> are preferably in phase such that the electrical stimulation signals are transmitted from electrode <NUM> to electrode <NUM> as shown by arrow <NUM>, to suppress vestibular activity.

In another example, electronics module <NUM>, <FIG>, where like parts have been given like numbers may generate DC signal <NUM> with imposed carrier waves <NUM> and <NUM> which are preferably temporally offset, e.g., <NUM> degrees out phase, with DC signal <NUM> with carrier waves <NUM> and <NUM> as shown. The result is current is transmitted from electrode <NUM> at its maximum current on one side of head <NUM> at a higher mastoid position to electrode <NUM> at zero current on an opposite side of head <NUM> a lower mastoid position, as shown by arrow <NUM>, and from electrode <NUM> at its maximum current on side of head <NUM> at a higher mastoid position to electrode <NUM> at zero current, on an opposite side of head <NUM> at a lower mastoid position, as shown by arrow <NUM>, to suppress vestibular activity.

Electronics module <NUM>, <FIG>, where like parts have been given like numbers may generate one or more electrical stimulation signals to suppress vestibular activity configured one or more AC signals. In one example, electronics module <NUM> preferably generates AC signal <NUM> by contact <NUM> which is applied to electrode <NUM> located on one side of head <NUM>, e.g., at location <NUM> <FIG>, of area <NUM> of the mastoid as shown, or any desired location on one side of head <NUM>. Electronics module <NUM> also generates AC signal <NUM> by contact <NUM> which is temporally offset, e.g., <NUM> degrees out of phase, with AC signal <NUM>. Ground electrode <NUM> is coupled to ground contact <NUM>. The result is the one or more AC signals are transmitted back and forth from one of electrodes <NUM>, <NUM> at its maximum positive current to one of electrodes <NUM>, <NUM> and its maximum negative current, as shown by arrow <NUM>, to suppress vestibular activity.

One embodiment of the method for suppressing vestibular activity in a human subject of this description includes generating one or more electrical stimulation signals, step <NUM>, <FIG>, and delivering one or more electrical stimulation signals to a plurality of electrodes each placed proximate a predetermined location on a head of the human subject such that the one or more electrical stimulation signals suppress vestibular activity of the human subject, step <NUM>.

Claim 1:
A system for suppressing vestibular activity of a human subject, the system comprising:
an electronics module (<NUM>) configured to generate at least first and second electrical stimulation signals, the first electrical stimulation signal including a first carrier signal and the second electrical stimulation signal including a second carrier signal, said first electrical stimulation signal being the first carrier signal imposed on a positive biased DC signal and said second electrical stimulation signal being the second carrier signal imposed on a negative biased DC signal;
a plurality of electrodes (<NUM>, <NUM>) including a first electrode (<NUM>, <NUM>) configured to be placed at an upper mastoid position on a side of a head (<NUM>) of the human subject and a second electrode (<NUM>, <NUM>) configured to be placed at a lower mastoid position on the same side of the head (<NUM>) of the human subject, and
wherein the electronics module is configured to modulate the current applied to respective electrodes (<NUM>, <NUM>, <NUM>, <NUM>) between <NUM> amps and a maximum positive/negative current and apply the first electrical stimulation signal to the first electrode while concurrently applying the second electrical stimulation signal to the second electrode to suppress vestibular activity of the human subject, the one or more electrical stimulation signals configured to hyperpolarize and/or depolarize cells located proximate the stimulation regions to suppress vestibular activity.