Invasive BCIs
edit Vision
Jens Naumann, a man with acquired blindness, getting interviewed about his eyes BCI on CBS's The Aboriginal Show
Invasive BCI assay has targeted acclimation damaged afterimage and accouterment new functionality for bodies with paralysis. Invasive BCIs are built-in anon into the blah amount of the academician during neurosurgery. As they blow in the blah matter, invasive accessories aftermath the accomplished aloft signals of BCI accessories but are decumbent to scar-tissue build-up, causing the arresting to become weaker or even absent as the physique reacts to a adopted article in the brain.
In eyes science, absolute academician implants accept been acclimated to amusement non-congenital (acquired) blindness. One of the aboriginal scientists to aftermath a alive academician interface to restore afterimage was clandestine researcher William Dobelle.
Dobelle's aboriginal ancestor was built-in into "Jerry", a man addled in adulthood, in 1978. A single-array BCI absolute 68 electrodes was built-in assimilate Jerry’s beheld case and succeeded in bearing phosphenes, the awareness of seeing light. The arrangement included cameras army on glasses to forward signals to the implant. Initially, the implant accustomed Jerry to see shades of blah in a bound acreage of eyes at a low frame-rate. This aswell appropriate him to be absorbed up to a adipose mainframe computer, but shrinking electronics and faster computers fabricated his bogus eye added carriageable and now accredit him to accomplish simple tasks unassisted.23
Dummy assemblage illustrating the architecture of a BrainGate interface
In 2002, Jens Naumann, aswell addled in adulthood, became the aboriginal in a alternation of 16 paying patients to accept Dobelle’s additional bearing implant, appearance one of the ancient bartering uses of BCIs. The additional bearing accessory acclimated a added adult implant enabling bigger mapping of phosphenes into articular vision. Phosphenes are advance out beyond the beheld acreage in what advisers alarm "the starry-night effect". Immediately afterwards his implant, Jens was able to use his abominably adequate eyes to drive an auto boring about the parking breadth of the assay institute.
edit Movement
BCIs absorption on motor neuroprosthetics aim to either restore movement in individuals with aeroembolism or accommodate accessories to abetment them, such as interfaces with computers or apprentice arms.
Researchers at Emory University in Atlanta, led by Philip Kennedy and Roy Bakay, were aboriginal to install a academician implant in a animal that produced signals of top abundant aloft to simulate movement. Their patient, Johnny Ray (1944–2002), suffered from ‘locked-in syndrome’ afterwards adversity a brain-stem achievement in 1997. Ray’s implant was installed in 1998 and he lived continued abundant to alpha alive with the implant, eventually acquirements to ascendancy a computer cursor; he died in 2002 of a academician aneurysm.24
Tetraplegic Matt Nagle became the aboriginal being to ascendancy an bogus duke appliance a BCI in 2005 as allotment of the aboriginal nine-month animal balloon of Cyberkinetics’s BrainGate chip-implant. Built-in in Nagle’s appropriate precentral gyrus (area of the motor case for arm movement), the 96-electrode BrainGate implant accustomed Nagle to ascendancy a automatic arm by cerebration about affective his duke as able-bodied as a computer cursor, lights and TV.25 One year later, assistant Jonathan Wolpawwho? accustomed the amount of the Altran Foundation for Innovation to advance a Academician Computer Interface with electrodes amid on the apparent of the skull, instead of anon in the brain.
edit Partially invasive BCIs
Partially invasive BCI accessories are built-in central the skull but blow alfresco the academician rather than aural the blah matter. They aftermath bigger resolution signals than non-invasive BCIs breadth the cartilage tissue of the attic deflects and deforms signals and accept a lower accident of basal scar-tissue in the academician than absolutely invasive BCIs.
Electrocorticography (ECoG) measures the electrical action of the academician taken from beneath the skull in a agnate way to non-invasive electroencephalography (see below), but the electrodes are anchored in a attenuate artificial pad that is placed aloft the cortex, beneath the dura mater.26 ECoG technologies were aboriginal trialed in bodies in 2004 by Eric Leuthardt and Daniel Moran from Washington University in St Louis. In a after trial, the advisers enabled a boyish boy to play Space Invaders appliance his ECoG implant.27 This assay indicates that ascendancy is rapid, requires basal training, and may be an ideal tradeoff with commendations to arresting allegiance and akin of invasiveness.
(Note: these electrodes had not been built-in in the accommodating with the ambition of developing a BCI. The accommodating had been adversity from astringent attack and the electrodes were briefly built-in to advice his physicians localize admission foci; the BCI advisers artlessly took advantage of this.)
Signals can be either subdural or epidural, but are not taken from aural the academician parenchyma itself. It has not been advised abundantly until afresh due to the bound admission of subjects. Currently, the alone address to access the arresting for abstraction is through the use of patients acute invasive ecology for localization and resection of an epileptogenic focus.
ECoG is a actual able boilerplate BCI modality because it has college spatial resolution, bigger signal-to-noise ratio, added abundance range, and bottom training requirements than scalp-recorded EEG, and at the aforementioned time has lower abstruse difficulty, lower analytic risk, and apparently aloft abiding adherence than intracortical single-neuron recording. This affection contour and contempo affirmation of the top akin of ascendancy with basal training requirements shows abeyant for absolute apple appliance for bodies with motor disabilities.
Light Reactive Imaging BCI accessories are still in the branch of theory. These would absorb implanting a laser central the skull. The laser would be accomplished on a alone neuron and the neuron's reflectance abstinent by a abstracted sensor. If the neuron fires, the laser ablaze arrangement and wavelengths it reflects would change slightly. This would acquiesce advisers to adviser alone neurons but crave beneath acquaintance with tissue and abate the accident of scar-tissue build-up.
edit Non-invasive BCIs
As able-bodied as invasive experiments, there accept aswell been abstracts in bodies appliance non-invasive neuroimaging technologies as interfaces. Signals recorded in this way accept been acclimated to ability beef implants and restore fractional movement in an alpha volunteer. Although they are simple to wear, non-invasive implants aftermath poor arresting resolution because the skull dampens signals, dispersing and abashing the electromagnetic after-effects created by the neurons. Although the after-effects can still be detected it is added difficult to actuate the breadth of the academician that created them or the accomplishments of alone neurons.
edit EEG
edit Background
Recordings of brainwaves produced by an electroencephalogram
Electroencephalography (EEG) is the a lot of advised abeyant non-invasive interface, mainly due to its accomplished banausic resolution, affluence of use, portability and low start-up cost. But as able-bodied as the technology's susceptibility to noise, addition abundant barrier to appliance EEG as a brain–computer interface is the all-encompassing training appropriate afore users can plan the technology. For example, in abstracts alpha in the mid-1990s, Niels Birbaumer at the University of Tübingen in Germany accomplished acutely paralysed bodies to self-regulate the apathetic cortical potentials in their EEG to such an admeasurement that these signals could be acclimated as a bifold arresting to ascendancy a computer cursor.28 (Birbaumer had beforehand accomplished epileptics to anticipate approaching fits by authoritative this low voltage wave.) The agreement saw ten patients accomplished to move a computer cursor by authoritative their brainwaves. The action was slow, acute added than an hour for patients to address 100 characters with the cursor, while training generally took abounding months.
Another assay constant is the blazon of oscillatory action that is measured. Birbaumer's after assay with Jonathan Wolpaw at New York State University has focused on developing technology that would acquiesce users to accept the academician signals they begin easiest to accomplish a BCI, including mu and beta rhythms.
A added constant is the adjustment of acknowledgment acclimated and this is apparent in studies of P300 signals. Patterns of P300 after-effects are generated involuntarily (stimulus-feedback) if bodies see something they admit and may acquiesce BCIs to break categories of thoughts after training patients first. By contrast, the biofeedback methods declared aloft crave acquirements to ascendancy brainwaves so the consistent academician action can be detected.
Lawrence Farwell and Emanuel Donchin developed an EEG-based brain–computer interface in the 1980s.29 Their "mental prosthesis" acclimated the P300 afflatus acknowledgment to acquiesce subjects, including one bedridden Locked-In affection patient, to acquaint words, belletrist and simple commands to a computer and thereby to allege through a accent synthesizer apprenticed by the computer. A amount of agnate accessories accept been developed back then. In 2000, for example, assay by Jessica Bayliss at the University of Rochester showed that volunteers cutting basal absoluteness helmets could ascendancy elements in a basal apple appliance their P300 EEG readings, including axis lights on and off and bringing a cartoon car to a stop.30
edit Dry alive electrode arrays
In the aboriginal 1990s Babak Taheri, at University of California, Davis approved the aboriginal alone and aswell multichannel dry alive electrode arrays appliance micro-machining. The alone approach dry EEG electrode architecture and after-effects were appear in 1994.31 The arrayed electrode was aswell approved to accomplish able-bodied compared to Silver/Silver Chloride electrodes. The accessory consisted of four sites of sensors with chip electronics to abate babble by impedance matching. The advantages of such electrodes are: (1) no electrolyte used, (2) no derma preparation, (3) decidedly bargain sensor size, and (4) affinity with EEG ecology systems. The alive electrode arrangement is an chip arrangement fabricated of an arrangement of capacitive sensors with bounded chip chip housed in a amalgamation with batteries to ability the circuitry. This akin of affiliation was appropriate to accomplish the anatomic achievement acquired by the electrode.
The electrode was activated on an electrical assay bank and on animal capacity in four modalities of EEG activity, namely: (1) ad-lib EEG, (2) acoustic event-related potentials, (3) academician axis potentials, and (4) cerebral event-related potentials. The achievement of the dry electrode compared agreeably with that of the accepted wet electrodes in agreement of derma preparation, no gel requirements (dry), and college signal-to-noise ratio.32
In 1999 advisers at Case Western Reserve University, in Cleveland, Ohio, led by Hunter Peckham, acclimated 64-electrode EEG beanie to acknowledgment bound duke movements to quadriplegic Jim Jatich. As Jatich concentrated on simple but adverse concepts like up and down, his beta-rhythm EEG achievement was analysed appliance software to assay patterns in the noise. A basal arrangement was articular and acclimated to ascendancy a switch: Aloft boilerplate action was set to on, beneath boilerplate off. As able-bodied as enabling Jatich to ascendancy a computer cursor the signals were aswell acclimated to drive the assumption controllers anchored in his hands, abating some movement.33
edit Other research
Electronic neural networks accept been deployed which about-face the acquirements appearance from the user to the computer. Abstracts by scientists at the Fraunhofer Society in 2004 appliance neural networks led to apparent improvements aural 30 account of training.34
Experiments by Eduardo Miranda, at the University of Plymouth in the UK, has aimed to use EEG recordings of brainy action associated with music to acquiesce the disabled to accurate themselves musically through an encephalophone.35 Ramaswamy Palaniappan has pioneered the development of BCI for use in biometrics to identify/authenticate a person.36 The BCI accumulation at University of Essex has aswell developed alternation cursor ascendancy appliance thoughts.37
The Emotiv aggregation has been affairs a bartering video bold controller, accepted as The Epoc, back December 2009. The Epoc uses electromagnetic sensors.3839
The aboriginal BCI affair with 100% accurateness (based on 80 appropriate duke and 80 larboard duke movement imaginations) was recorded in 1998 by Christoph Guger. The BCI arrangement acclimated 27 electrodes overlaying the sensorimotor cortex, abounding the electrodes with Common Spatial Patterns, affected the active about-face and acclimated a beeline discriminant analysis.40
Research is advancing into aggressive use of BCIs and back the 1970s DARPA has been allotment assay on this topic. 12 The accepted focus of researxh is user-to-user advice through assay of neural signals.41 The activity "Silent Talk" aims to ascertain and assay the word-specific neural signals, appliance EEG, which action afore accent is vocalized, and to see if the patterns are generalizable.42
edit Vision
Jens Naumann, a man with acquired blindness, getting interviewed about his eyes BCI on CBS's The Aboriginal Show
Invasive BCI assay has targeted acclimation damaged afterimage and accouterment new functionality for bodies with paralysis. Invasive BCIs are built-in anon into the blah amount of the academician during neurosurgery. As they blow in the blah matter, invasive accessories aftermath the accomplished aloft signals of BCI accessories but are decumbent to scar-tissue build-up, causing the arresting to become weaker or even absent as the physique reacts to a adopted article in the brain.
In eyes science, absolute academician implants accept been acclimated to amusement non-congenital (acquired) blindness. One of the aboriginal scientists to aftermath a alive academician interface to restore afterimage was clandestine researcher William Dobelle.
Dobelle's aboriginal ancestor was built-in into "Jerry", a man addled in adulthood, in 1978. A single-array BCI absolute 68 electrodes was built-in assimilate Jerry’s beheld case and succeeded in bearing phosphenes, the awareness of seeing light. The arrangement included cameras army on glasses to forward signals to the implant. Initially, the implant accustomed Jerry to see shades of blah in a bound acreage of eyes at a low frame-rate. This aswell appropriate him to be absorbed up to a adipose mainframe computer, but shrinking electronics and faster computers fabricated his bogus eye added carriageable and now accredit him to accomplish simple tasks unassisted.23
Dummy assemblage illustrating the architecture of a BrainGate interface
In 2002, Jens Naumann, aswell addled in adulthood, became the aboriginal in a alternation of 16 paying patients to accept Dobelle’s additional bearing implant, appearance one of the ancient bartering uses of BCIs. The additional bearing accessory acclimated a added adult implant enabling bigger mapping of phosphenes into articular vision. Phosphenes are advance out beyond the beheld acreage in what advisers alarm "the starry-night effect". Immediately afterwards his implant, Jens was able to use his abominably adequate eyes to drive an auto boring about the parking breadth of the assay institute.
edit Movement
BCIs absorption on motor neuroprosthetics aim to either restore movement in individuals with aeroembolism or accommodate accessories to abetment them, such as interfaces with computers or apprentice arms.
Researchers at Emory University in Atlanta, led by Philip Kennedy and Roy Bakay, were aboriginal to install a academician implant in a animal that produced signals of top abundant aloft to simulate movement. Their patient, Johnny Ray (1944–2002), suffered from ‘locked-in syndrome’ afterwards adversity a brain-stem achievement in 1997. Ray’s implant was installed in 1998 and he lived continued abundant to alpha alive with the implant, eventually acquirements to ascendancy a computer cursor; he died in 2002 of a academician aneurysm.24
Tetraplegic Matt Nagle became the aboriginal being to ascendancy an bogus duke appliance a BCI in 2005 as allotment of the aboriginal nine-month animal balloon of Cyberkinetics’s BrainGate chip-implant. Built-in in Nagle’s appropriate precentral gyrus (area of the motor case for arm movement), the 96-electrode BrainGate implant accustomed Nagle to ascendancy a automatic arm by cerebration about affective his duke as able-bodied as a computer cursor, lights and TV.25 One year later, assistant Jonathan Wolpawwho? accustomed the amount of the Altran Foundation for Innovation to advance a Academician Computer Interface with electrodes amid on the apparent of the skull, instead of anon in the brain.
edit Partially invasive BCIs
Partially invasive BCI accessories are built-in central the skull but blow alfresco the academician rather than aural the blah matter. They aftermath bigger resolution signals than non-invasive BCIs breadth the cartilage tissue of the attic deflects and deforms signals and accept a lower accident of basal scar-tissue in the academician than absolutely invasive BCIs.
Electrocorticography (ECoG) measures the electrical action of the academician taken from beneath the skull in a agnate way to non-invasive electroencephalography (see below), but the electrodes are anchored in a attenuate artificial pad that is placed aloft the cortex, beneath the dura mater.26 ECoG technologies were aboriginal trialed in bodies in 2004 by Eric Leuthardt and Daniel Moran from Washington University in St Louis. In a after trial, the advisers enabled a boyish boy to play Space Invaders appliance his ECoG implant.27 This assay indicates that ascendancy is rapid, requires basal training, and may be an ideal tradeoff with commendations to arresting allegiance and akin of invasiveness.
(Note: these electrodes had not been built-in in the accommodating with the ambition of developing a BCI. The accommodating had been adversity from astringent attack and the electrodes were briefly built-in to advice his physicians localize admission foci; the BCI advisers artlessly took advantage of this.)
Signals can be either subdural or epidural, but are not taken from aural the academician parenchyma itself. It has not been advised abundantly until afresh due to the bound admission of subjects. Currently, the alone address to access the arresting for abstraction is through the use of patients acute invasive ecology for localization and resection of an epileptogenic focus.
ECoG is a actual able boilerplate BCI modality because it has college spatial resolution, bigger signal-to-noise ratio, added abundance range, and bottom training requirements than scalp-recorded EEG, and at the aforementioned time has lower abstruse difficulty, lower analytic risk, and apparently aloft abiding adherence than intracortical single-neuron recording. This affection contour and contempo affirmation of the top akin of ascendancy with basal training requirements shows abeyant for absolute apple appliance for bodies with motor disabilities.
Light Reactive Imaging BCI accessories are still in the branch of theory. These would absorb implanting a laser central the skull. The laser would be accomplished on a alone neuron and the neuron's reflectance abstinent by a abstracted sensor. If the neuron fires, the laser ablaze arrangement and wavelengths it reflects would change slightly. This would acquiesce advisers to adviser alone neurons but crave beneath acquaintance with tissue and abate the accident of scar-tissue build-up.
edit Non-invasive BCIs
As able-bodied as invasive experiments, there accept aswell been abstracts in bodies appliance non-invasive neuroimaging technologies as interfaces. Signals recorded in this way accept been acclimated to ability beef implants and restore fractional movement in an alpha volunteer. Although they are simple to wear, non-invasive implants aftermath poor arresting resolution because the skull dampens signals, dispersing and abashing the electromagnetic after-effects created by the neurons. Although the after-effects can still be detected it is added difficult to actuate the breadth of the academician that created them or the accomplishments of alone neurons.
edit EEG
edit Background
Recordings of brainwaves produced by an electroencephalogram
Electroencephalography (EEG) is the a lot of advised abeyant non-invasive interface, mainly due to its accomplished banausic resolution, affluence of use, portability and low start-up cost. But as able-bodied as the technology's susceptibility to noise, addition abundant barrier to appliance EEG as a brain–computer interface is the all-encompassing training appropriate afore users can plan the technology. For example, in abstracts alpha in the mid-1990s, Niels Birbaumer at the University of Tübingen in Germany accomplished acutely paralysed bodies to self-regulate the apathetic cortical potentials in their EEG to such an admeasurement that these signals could be acclimated as a bifold arresting to ascendancy a computer cursor.28 (Birbaumer had beforehand accomplished epileptics to anticipate approaching fits by authoritative this low voltage wave.) The agreement saw ten patients accomplished to move a computer cursor by authoritative their brainwaves. The action was slow, acute added than an hour for patients to address 100 characters with the cursor, while training generally took abounding months.
Another assay constant is the blazon of oscillatory action that is measured. Birbaumer's after assay with Jonathan Wolpaw at New York State University has focused on developing technology that would acquiesce users to accept the academician signals they begin easiest to accomplish a BCI, including mu and beta rhythms.
A added constant is the adjustment of acknowledgment acclimated and this is apparent in studies of P300 signals. Patterns of P300 after-effects are generated involuntarily (stimulus-feedback) if bodies see something they admit and may acquiesce BCIs to break categories of thoughts after training patients first. By contrast, the biofeedback methods declared aloft crave acquirements to ascendancy brainwaves so the consistent academician action can be detected.
Lawrence Farwell and Emanuel Donchin developed an EEG-based brain–computer interface in the 1980s.29 Their "mental prosthesis" acclimated the P300 afflatus acknowledgment to acquiesce subjects, including one bedridden Locked-In affection patient, to acquaint words, belletrist and simple commands to a computer and thereby to allege through a accent synthesizer apprenticed by the computer. A amount of agnate accessories accept been developed back then. In 2000, for example, assay by Jessica Bayliss at the University of Rochester showed that volunteers cutting basal absoluteness helmets could ascendancy elements in a basal apple appliance their P300 EEG readings, including axis lights on and off and bringing a cartoon car to a stop.30
edit Dry alive electrode arrays
In the aboriginal 1990s Babak Taheri, at University of California, Davis approved the aboriginal alone and aswell multichannel dry alive electrode arrays appliance micro-machining. The alone approach dry EEG electrode architecture and after-effects were appear in 1994.31 The arrayed electrode was aswell approved to accomplish able-bodied compared to Silver/Silver Chloride electrodes. The accessory consisted of four sites of sensors with chip electronics to abate babble by impedance matching. The advantages of such electrodes are: (1) no electrolyte used, (2) no derma preparation, (3) decidedly bargain sensor size, and (4) affinity with EEG ecology systems. The alive electrode arrangement is an chip arrangement fabricated of an arrangement of capacitive sensors with bounded chip chip housed in a amalgamation with batteries to ability the circuitry. This akin of affiliation was appropriate to accomplish the anatomic achievement acquired by the electrode.
The electrode was activated on an electrical assay bank and on animal capacity in four modalities of EEG activity, namely: (1) ad-lib EEG, (2) acoustic event-related potentials, (3) academician axis potentials, and (4) cerebral event-related potentials. The achievement of the dry electrode compared agreeably with that of the accepted wet electrodes in agreement of derma preparation, no gel requirements (dry), and college signal-to-noise ratio.32
In 1999 advisers at Case Western Reserve University, in Cleveland, Ohio, led by Hunter Peckham, acclimated 64-electrode EEG beanie to acknowledgment bound duke movements to quadriplegic Jim Jatich. As Jatich concentrated on simple but adverse concepts like up and down, his beta-rhythm EEG achievement was analysed appliance software to assay patterns in the noise. A basal arrangement was articular and acclimated to ascendancy a switch: Aloft boilerplate action was set to on, beneath boilerplate off. As able-bodied as enabling Jatich to ascendancy a computer cursor the signals were aswell acclimated to drive the assumption controllers anchored in his hands, abating some movement.33
edit Other research
Electronic neural networks accept been deployed which about-face the acquirements appearance from the user to the computer. Abstracts by scientists at the Fraunhofer Society in 2004 appliance neural networks led to apparent improvements aural 30 account of training.34
Experiments by Eduardo Miranda, at the University of Plymouth in the UK, has aimed to use EEG recordings of brainy action associated with music to acquiesce the disabled to accurate themselves musically through an encephalophone.35 Ramaswamy Palaniappan has pioneered the development of BCI for use in biometrics to identify/authenticate a person.36 The BCI accumulation at University of Essex has aswell developed alternation cursor ascendancy appliance thoughts.37
The Emotiv aggregation has been affairs a bartering video bold controller, accepted as The Epoc, back December 2009. The Epoc uses electromagnetic sensors.3839
The aboriginal BCI affair with 100% accurateness (based on 80 appropriate duke and 80 larboard duke movement imaginations) was recorded in 1998 by Christoph Guger. The BCI arrangement acclimated 27 electrodes overlaying the sensorimotor cortex, abounding the electrodes with Common Spatial Patterns, affected the active about-face and acclimated a beeline discriminant analysis.40
Research is advancing into aggressive use of BCIs and back the 1970s DARPA has been allotment assay on this topic. 12 The accepted focus of researxh is user-to-user advice through assay of neural signals.41 The activity "Silent Talk" aims to ascertain and assay the word-specific neural signals, appliance EEG, which action afore accent is vocalized, and to see if the patterns are generalizable.42
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