Brain-Computer Interface (BCI)

Brain Computer Interfaces (BCI) hold great fascination for technology and science. In medicine, they refer to systems that detect neural activity and use it as a trigger for certain medically relevant actions.

Medical applications of this technology that are particularly intensively explored include neuronally controlled assistive systems for severely paralyzed people. They provide patients with means for communication or motor assistance for example through robot arms. In recent years, more and more scientific evidence suggests that such systems can also be used for rehabilitation purposes.

In research environment, these technologies have already achieved remarkable successes. However, there are currently no such systems yet that would be suitable for everyday use.

– As assistive systems for severely paralyzed patients, e.g. with ALS or spinal cord injury

Paralyses that occur, e.g. after severe strokes, spinal cord injuries, or in the progressive muscular atrophy disease ALS (by which the well-known physicist Stephen Hawking was afflicted, for example) can be so severe that patients can no longer communicate in a normal way. This case is called locked-in syndrome.

When even eye movements or twitching of individual muscles become impossible, the patients are completely “locked in” (complete Locked-in syndrome).

The inability to control their environment and to communicate with relatives and caregivers makes this state especially difficult for the patients – in particular, because they can at the same time remain fully conscious.

The Potential of Neurotechnology

In many cases, the brains of paralyzed patients are still intact. In these cases, neurotechnological devices can be used to create so-called brain-computer interfaces. Patients can control these independently from any remaining muscle activity – only through the power of their thoughts.

The easiest way to capture brain activity is by the encephalogram (EEG). A recently found alternative is functional near-infrared spectroscopy (fNIRS). However, the amount of information that can be collected through the skull by these two noninvasive methods is very limited. The same applies to the stability of the recorded signals. Moreover, both methods are highly susceptible to environmental disturbances, such as radio or cell phone signals (Rosenfeld & Wong, 2017, Shih et al., 2012).

Stronger and more stable signals with better spatial resolution can be recorded by electrodes that are placed within the skull. They sit directly on the brain or the meninges, or are inserted into the brain tissue. For such systems to be suitable for everyday use, however, fast and secure data processing must be guaranteed, and the applied hardware must be compact and portable.

Interfacing motor nerves potentially can restore the mobility of muscles. The bioelectronic medicine recently has begun to research this approach.

State of Research and Technology

There is a number of different kinds of assistive systems that severely paralyzed persons can use in everyday life. All of them, however, are based on remaining motor functions of the patient. Wheelchairs and other devices can be controlled by the movement of the eyes, the tongue or even by breathing (so-called “sip and puff” control). Locked-In patients who do not have any of such residual functions, therefore, cannot use these systems.

In neuroscientific research there are many approaches to enable neuronal control of wheelchairs, orthoses, communication systems, and other aids, just through neuronal signals.

While impressive results haven been achieved by such non-invasive (Chaudary et al., 2016) or invasive BCIs (Bacher et al., 2015; Branco et al., 2017; Collinger at al., 2014; Wang et al., 2013), these systems are still far from being fit for everyday use and being certified for broad clinical application.

Solutions supported by CorTec Technology

CorTec’s °AirRay Electrodes can be used both for both recording and stimulating brain activity, and can thus transmit information in both directions. Thanks to CorTec’s flexible manufacturing technology the shape, spacing, and number of electrode contacts can be adapted to the application at hand as well as to the individual patient. °AirRay Cuff Electrodes can also target motor nerves with the goal of restoring natural mobility.

Combined with intelligent decoding software as applied through CorTec’s Brain Interchange technology a direct link between the human brain and artificial intelligence can be created that could allow even the most severely paralyzed to interact again with their environments.

With its large number of currently 32 channels, the Brain Interchange System is engineered to support unprecedented intensities of information transfer. This will allow exploring a neural control of precise assistive devices as well as restoration of mobility through the body’s own muscles.

 

CorTec °AirRay Grid and Cuff Electrodes can be used in a wide range of designs, in scientific studies and as components of complete therapeutic systems. The Brain Interchange System is currently still under development. Initial clinical pilot studies are in preparation to demonstrate safety and functionality of the system. A collaborative project (link to the R & D Projects page) conducted in cooperation with the University Medical Center in Freiburg investigates brain-computer interfaces as assistive systems for the paralyzed.

– For Rehabilitation, e.g., after stroke

After a stroke, many patients are left with paralyses, that permanently affect them in their daily lives, and which sometimes cannot even be remedied by intensive rehabilitation.

The Potential of Neurotechnology

By visualizing certain movements these stroke patients can frequently still generate the brain signals that – under healthy conditions – would elicit those movements. Brain-computer interfaces that detect such movement intentions in the electrical signals of the brain and based on this data control assistive devices such as orthoses could – at least partially – restore patients’ mobility.

By training with the brain-computer interface the patients can learn to move their limbs with the aid of the assistive device. Pilot studies have already achieved remarkable successes in BCI-mediated motor rehabilitation after stroke (Frolov et al., 2017; Bundy  et al., 2017; Monge-Pereira et al., 2017; Chaudhary et al., 2016).

Research results also suggest that successful training helps to establish new neuronal connections that can improve natural mobility even without the assistive devices (Biasiucci et al., 2018).

Neurotechnology could, thus, open up new ways of rehabilitation and positively affect motor disabilities that previously could not be addressed by existing measures.

State of Research and Technology

Currently, stroke rehabilitation mainly consists of passive movement therapy in which the patient follows a certain movement rhythm.

In addition brain-computer interfaces are being used to explore potential new forms of rehabilitation, mainly using non-invasively recorded signals such as the electroencephalogram (EEG; see Frolov et al., 2017; Bundy et al., 2017; Monge-Pereira et al., 2017; Chaudhary et al., 2016).

However, the accuracy and informational content of neuronal signals – and, thus, also the decodability for brain-computer interfaces – become better, if signals from within the skull, recorded directly from the surface of the brain, are used for their control (Rosenfeld & Wong, 2017; Shih et al., 2012).

Therefore, also using invasively derived brain signals for brain-computer interfaces for stroke rehabilitation is currently considered (Gharabaghi ​​et al., 2014; Wang et al., 2010). To date, however, there is no stroke rehabilitation system based on brain-computer interfaces yet that would be approved for general clinical use.

A different approach to stroke rehabilitation is based on electrical stimulation of the motor cortex during motor training. The US company Northstar Neuroscience which developed a corresponding neurostimulator achieved promising results in the 2000s with such an electrically assisted rehabilitation scheme (Brown et al., 2003; Brown et al., 2006). A subsequent larger clinical trial revealed positive long-term improvements, but no short-term benefits (Levy et al., 2016). Future studies (possibly with better technology, better trial design and improved patient selection criteria) are needed to clarify the potential of cortical stimulation in stroke rehabilitation.

Solutions supported by CorTec Technology

CorTec’s flat °AirRay Grid electrodes are useful for both recording and stimulating brain activity and can thus transmit information in both directions. Thanks to CorTec’s flexible manufacturing technology, the shape, spacing and number of electrode contacts can be individually adapted to the application at hand as well as to the individual patient.

 

Combining the °AirRay electrodes with the CorTec Brain Interchange Implant System it is possible to wirelessly transfer the data to a computing unit outside of the body. This unit analyzes the data and processes them further to derive movement control signals. In this way, the system enables fast interactions between the brain and the limbs.

 

The CorTec °AirRay Grid electrodes can be used in a wide range of designs, in scientific studies and as components of complete therapeutic systems. The Brain Interchange System is currently still under development. Initial clinical pilot studies are in preparation to demonstrate safety and functionality of the system. A collaborative project (link to the R & D projects page) conducted with the University Medical Center in Tübingen, Germany, aims to explore the foundations for novel rehabilitation systems for paralyzed people.

Further Readings

Scientific Literature

As assistive systems for severely paralyzed patients

Brain-computer interfaces in the completely locked-in state and chronic stroke.

Chaudhary U, Birbaumer N, Ramos-Murguialday A.

Prog Brain Res. 2016;228:131-61. doi: 10.1016/bs.pbr.2016.04.019. Epub 2016 Aug 8. Review.

 

Neurobionics and the brain-computer interface: current applications and future horizons.

Rosenfeld JV, Wong YT.

Med J Aust. 2017 May 1;206(8):363-368. Review.

 

Brain-computer interfaces in medicine.

Shih JJ, Krusienski DJ, Wolpaw JR.

Mayo Clin Proc. 2012 Mar;87(3):268-79. doi: 10.1016/j.mayocp.2011.12.008. Epub 2012 Feb 10. Review.

 

Neural Point-and-Click Communication by a Person With Incomplete Locked-In Syndrome.

Bacher D, Jarosiewicz B, Masse NY, Stavisky SD, Simeral JD, Newell K, Oakley EM, Cash SS, Friehs G, Hochberg LR.

Neurorehabil Neural Repair. 2015 Jun;29(5):462-71. doi: 10.1177/1545968314554624. Epub 2014 Nov 10.

 

Decoding hand gestures from primary somatosensory cortex using high-density ECoG.

Branco MP, Freudenburg ZV, Aarnoutse EJ, Bleichner MG, Vansteensel MJ, Ramsey NF.

Neuroimage. 2017 Feb 15;147:130-142. doi: 10.1016/j.neuroimage.2016.12.004. Epub 2016 Dec 5.

 

Collaborative approach in the development of high-performance brain-computer interfaces for a neuroprosthetic arm: translation from animal models to human control.

Collinger JL, Kryger MA, Barbara R, Betler T, Bowsher K, Brown EH, Clanton ST, Degenhart AD, Foldes ST, Gaunt RA, Gyulai FE, Harchick EA, Harrington D, Helder JB, Hemmes T, Johannes MS, Katyal KD, Ling GS, McMorland AJ, Palko K, Para MP, Scheuermann J, Schwartz AB, Skidmore ER, Solzbacher F, Srikameswaran AV, Swanson DP, Swetz S, Tyler-Kabara EC, Velliste M, Wang W, Weber DJ, Wodlinger B, Boninger ML.

Clin Transl Sci. 2014 Feb;7(1):52-9. doi: 10.1111/cts.12086. Epub 2013 Aug 27.

 

An electrocorticographic brain interface in an individual with tetraplegia.

Wang W, Collinger JL, Degenhart AD, Tyler-Kabara EC, Schwartz AB, Moran DW, Weber DJ, Wodlinger B, Vinjamuri RK, Ashmore RC, Kelly JW, Boninger ML.

PLoS One. 2013;8(2):e55344. doi: 10.1371/journal.pone.0055344. Epub 2013 Feb 6.

For Rehabilitation

Post-stroke Rehabilitation Training with a Motor-Imagery-Based Brain-Computer Interface (BCI)-Controlled Hand Exoskeleton: A Randomized Controlled Multicenter Trial.

Frolov AA, Mokienko O, Lyukmanov R, Biryukova E, Kotov S, Turbina L, Nadareyshvily G, Bushkova Y.

Front Neurosci. 2017 Jul 20;11:400. doi: 10.3389/fnins.2017.00400. eCollection 2017.

 

Contralesional Brain-Computer Interface Control of a Powered Exoskeleton for Motor Recovery in Chronic Stroke Survivors.

Bundy DT, Souders L, Baranyai K, Leonard L, Schalk G, Coker R, Moran DW, Huskey T, Leuthardt EC.

Stroke. 2017 Jul;48(7):1908-1915. doi: 10.1161/STROKEAHA.116.016304. Epub 2017 May 26.

 

Use of Electroencephalography Brain-Computer Interface Systems as a Rehabilitative Approach for Upper Limb Function After a Stroke: A Systematic Review.

Monge-Pereira E, Ibañez-Pereda J, Alguacil-Diego IM, Serrano JI, Spottorno-Rubio MP, Molina-Rueda F.

PM R. 2017 May 13. pii: S1934-1482(17)30581-6. doi: 10.1016/j.pmrj.2017.04.016.

 

Brain-computer interfaces in the completely locked-in state and chronic stroke.

Chaudhary U, Birbaumer N, Ramos-Murguialday A.

Prog Brain Res. 2016;228:131-61. doi: 10.1016/bs.pbr.2016.04.019. Epub 2016 Aug 8. Review.

 

Brain-actuated functional electrical stimulation elicits lasting arm motor recovery after stroke.

Biasiucci A, Leeb R, Iturrate I, Perdikis S, Al-Khodairy A, Corbet T, Schnider A, Schmidlin T, Zhang H, Bassolino M, Viceic D, Vuadens P, Guggisberg AG, Millán JDR.

Nat Commun. 2018 Jun 20;9(1):2421. doi: 10.1038/s41467-018-04673-z.

 

From assistance towards restoration with epidural brain-computer interfacing.

Gharabaghi A, Naros G, Walter A, Grimm F, Schuermeyer M, Roth A, Bogdan M, Rosenstiel W, Birbaumer N.

Restor Neurol Neurosci. 2014;32(4):517-25. doi: 10.3233/RNN-140387.

 

Neural interface technology for rehabilitation: exploiting and promoting neuroplasticity.

Wang W, Collinger JL, Perez MA, Tyler-Kabara EC, Cohen LG, Birbaumer N, Brose SW, Schwartz AB, Boninger ML, Weber DJ.

Phys Med Rehabil Clin N Am. 2010 Feb;21(1):157-78. doi: 10.1016/j.pmr.2009.07.003. Review.

 

Northstar study papers:

Brown JA, Lutsep H, Cramer SC, Weinand M. Motor cortex stimulation for enhancement of recovery after stroke: case report. Neurol Res. 2003 Dec;25(8):815-8.

Brown JA, Lutsep HL, Weinand M, Cramer SC. Motor cortex stimulation for the enhancement of recovery from stroke: a prospective, multicenter safety study. Neurosurgery. 2006 Mar;58(3):464-73.

Levy RM, Harvey RL, Kissela BM, Winstein CJ, Lutsep HL, Parrish TB, Cramer SC, Venkatesan L. Epidural Electrical Stimulation for Stroke Rehabilitation: Results of the Prospective, Multicenter, Randomized, Single-Blinded Everest Trial. Neurorehabil Neural Repair. 2016 Feb;30(2):107-19. doi: 10.1177/1545968315575613. Epub 2015 Mar 6.