evaluation of individuals , in certain occupations , for a propensity to suffer from motion sickness requires an object determination of the early onset of motion sickness . similarly , the study of new anti - motion sickness interventions requires reproducible and object analysis of motion sickness onset . however , previous imaging methods , used to determine the onset of motion sickness , have yielded inconsistent results and are , therefore , of limited value . more refined methods of motion sickness are needed for these and other applications . an aspect of the current invention , therefore , is a method for evaluating of the onset of motion sickness incorporating a more refined determination of the relevant regions of the brain . the overall inventive method of objective determination of motion sickness comprises the identification of the suppression of 20 and 40 hz peaks in the central posterior ( occipital ) region / ventral intraparietal area during the onset of motion sickness . applicants contemplate that the inventive method would be useful in a number areas including clinical evaluation and screening of patients suffering from motion sickness to occupational evaluation of astronauts , pilots and shipboard crews to the design of vehicles in order to minimize motion sickness and in the design of motion simulators . in addition to identifying motion sickness onset , this method could lead to effective a biofeedback training techniques to prevent the onset of motion sickness in motion sick susceptible individuals or individuals who want to decrease their susceptibility to motion sickness . individuals would first be taught to identify and discriminate 20 and 40 hz peak states in non - motion and non - virtual moving environment using eeg biofeedback . an extensive ( 32 - 128 electrode ) or selected array ( 4 - 16 electrodes ) could be used to provide biofeedback for training . individuals would next be exposed to a virtual motion ( mildly nauseagenic ) environment and practice maintaining or increasing 20 and 40 hz peaks . finally , the inventive method comprises having individuals practice maintaining or increasing 20 and 40 hz peaks in actual motion environments . the following example is provided to better illustrate the utility of the subject invention . in this example , subjects were recruited that had the following criteria : a . healthy male and female between ages 18 and 50 years old . b . motion sickness susceptible as determined by self - reported answers to the motion history questionnaire ( mhq ). the mhq was a version of the mhq used by kennedy and graybiel , 1965 . c . receipt of written clearance after an in - person neurological exam conducted by a medical monitor . subject exclusion criteria included pregnancy or any person currently on medication for motion sickness , taking sedatives , anticonvulsants , or stimulants , or with a history of seizure disorder , stroke , or brain injury . the eeg of the subjects was recorded using the biosemi activetwo ™ system ( biosemi , amsterdam , netherlands ), equipped with 128 - channels , a dc amplifier , 24 - bit resolution , and a biopotential measurement system with active ag / agcl electrodes . the active two ™ device features a stretchable head cap system that obtains reliable measurements without skin preparation . the amplifier for the electrodes are housed in the electrode casing , and the electrodes are positioned according to the 10 - 20 - electrode system . horizontal electrooculography ( eog ) was recorded from one electrode placed at the outer canthi of the left eye . vertical eog was recorded from two electrodes placed on the infraorbital and supraorbital regions of the right eye in line with the pupil . eeg signals were band - pass filtered at a sampling rate of 256 hz . a flow filed video , used in the study , consisted of erratically rotating rectangles that were black and white with dots in them . the boxes appeared to diverge or converge as they rotated erratically . a ball - tracking task was used as a cognitive / behavioral performance measure . the task involved utilizing a computer mouse to move a ball projected onto a computer screen into the center of a fixed circle . the ball moved randomly in different directions on the screen and the user had to constantly move the computer mouse to relocate the ball within the center of the circle . all potential subjects were first screened via telephone or in person and informed of their eligibility to participate immediately after completing the mhq . the primary criteria for inclusion into the study was if subjects answered questions on the mhq suggesting that they had a history of experiencing motion sickness while flying , riding as a passenger in an automobile or while on a boat / ship . subjects who also indicated that they experienced motion sickness while viewing certain images on a computer , television or big screen movie were also considered susceptible to motion sickness . subjects were asked to abstain from food and beverage for 2 hours prior to study participation in order to reduce the risk of vomiting . subjects were seated in a darkened room in a standard office swivel chair 5 feet from a wall that was used as a projection screen . a tape measure was used to measure the size of their head from nasium to inin in order to select the proper - sized eeg cap . the forehead region was scrubbed lightly with a sterile alcohol pad and a functional near - infrared spectroscopy ( fnirs ) encasement containing an infrared emitter and detector was placed on the forehead with the detector placed 4 cm above the nasium and centered on the forehead . the emitter was placed 3 cm horizontal and to the right of the detector with the encasement for the fnir emitter / transducer initially held in place by double - sided tape . the eeg cap was then lapped over the fnirs encasement and stretched over the ears and around and beyond the occipital protuberance . the eeg cap was used to pull the chinstrap on the eeg cap taut and affix the velcro straps under their chin together . approximately 120 of the 128 electrode holders of the eeg cap were then filled with eeg gel and the electrodes inserted . while checking the eeg electrodes , the ball - tracking task was explained to the subjects and they were allowed to practice the task for approximately 5 minutes . as the brain monitoring equipment was being set up it was explained to the subjects that at several points during the experiment they would be asked to rate their sense of motion and degree of motion sickness on a scale of 0 - 3 by showing number of fingers . after the brain monitoring equipment was recording the subjects were asked to close their eyes and raise their feet off the floor . to demonstrate motion sensation they were then rotated back and forth on their chair at approximately 0 . 5 hz for 8 - 10 seconds . after rotating them they were asked to open their eyes and report the extent to which they felt as though they were still moving on the previously explained rating scale of 0 - 3 . all subjects were videotaped and monitored in real - time to monitor subjects for signs of motion sickness . the procedure for the study began with obtaining a 5 - minute baseline that consisted of the subject sitting quietly while viewing a still screen capture of the flow field . this screen capture of the flow filed was immediately followed by 3 minutes of the ball - tracking task . immediately after the ball - tracking task ended , session 1 began with subjects viewing the moving flow filed ( 3 minutes ). the flow field was then terminated , and 1 minute of the ball tracking - only task began . as the subject was performing the ball - tracking task the flow field also appeared on the screen after 1 minute and lasted for 3 minutes . immediately after the combined task ended there was an assessment in which subjects were asked to rate their degree of motion sensation and motion sickness by showing a number of fingers or the “ ok ” sign for zero . the sequence for session 1 was repeated for session 2 . session 3 consisted of viewing the driving video for 90 seconds , stopping the video to assess motion sense and motion sickness and then performing the tracking task for 1 minute . this process was repeated for session 4 . for session 5 , subjects viewed the driving video for 3 minutes and then were assessed for motion sense and motion sickness . prior to eeg data analysis the following procedure was followed in preparing the data : 1 ) data were first visually inspected for bad channels and bad epochs , which were rejected ; and 2 ) data were high passed for 1 hz and low passed at 50 hz . the largest amount of variance in eeg activity in 3 of 4 subjects corresponded to frontal activity ( e . g . independent component # 1 ), which was expected and typically is indicative of eye movement . as an illustration , the reader is referred to fig1 . these components show higher activity in motion sickness subjects in the range of 1 - 10 hz . subjects also tended to demonstrate increased spectral power across all frequencies in the range of 3 to 8 db when comparing baseline measures with motion sickness epochs , as illustrated in fig2 . some subjects demonstrated selective local increases in spectral power in the 20 - 50 hz range , as illustrated in fig3 . the independent components demonstrating this effect appear to be external muscles on the skull . some subjects reported jaw clenching and other muscle tension associated with their motion sickness . there was a central posterior ( occipital ) independent component in our motion sickness subjects that shows 20 hz and 40 hz peaks in the baseline condition and the suppression of these peaks during the motion sickness condition . this observation is illustrated in fig4 . 1 . chelen , w ., m . kabrisky , s . rogers . 1993 . spectral analysis of the electroencephalographic response to motion sickness . aviation space environmental medicine . 64 : 24 - 29 . 2 . de metz , k ., o . quadens , m . de graaeve . 1994 . quantified eeg in different g situations . acta astronaut . 32 : 151 - 157 . 3 . dornhoffer , j . n . mamiya , p . bray , r . skinner , e . garcia - rill . 2003 . effects of rotation on the sleep state - dependent midlatency auditory evoked p50 potential in the human . journal of vestibular research ( 2002 - 2003 ); 12 : 205 - 209 . 4 . ferrari , m ., l . mottola , q . valentine . 2004 . principles , techniques and limitations of near infrared spectroscopy . canadian journal of applied physiology . 29 : 463 - 487 . 5 . hoshi , y . 2003 . functional near - infrared optical imaging : utility and limitations in human brain mapping . psychophysiology 40 : 511 - 520 . 6 . jasdzewski , g ., g . strangman , j . wagner , k . kwong , r . poldrack , d . boas . 2003 . differences in the hemodynamic response to event - related motor and visual paradigms as measured by near - infrared spectroscopy . neurolmage 20 : 479 - 488 . 7 . min , b . s . chung , y . min , k . sakamoto . 2004 . psychophysiological evaluation of simulator sickness evoked by graphic simulator . applied ergonomics 35 : 549 - 556 . 8 . obrig , h . a . villringer . 2003 . beyond the visible - imaging the human brain with light . j . cereb blood flow metab . 23 : 1 - 18 . 9 . villringer , a . 1997 . understanding functional neuroimaging methods based on neurovascular coupling . adv . exp . med . biol . 413 : 177 - 193 . having described the invention , one of skill in the art will appreciate in the appended claims that many modifications and variations of the present invention are possible in light of the above teachings . it is therefore , to be understood that , within the scope of the claims , the invention may be practiced otherwise than as specifically described .
the invention relates to a method of determining early onset of motion sickness by brain imaging . the method discloses an objective means of determining the onset of motion sickness by evaluating a specific region of the brain . the method can also be utilized in evaluating the predisposition toward motion sickness in workers in occupations prone to motion sickness .