Brain-computer interface 

R&H Brain interface topA Brain-Computer Interface (BCI) is a system that allows you to interact with a computer by means of your brain signals. The system typically consists of a computer, an amplifier and a skullcap. The BCI reads off brain signals and transmits them directly to a computer, bypassing the neuromuscular system through which we usually interact with the world. In other words, all you have to do is to focus on a task you wish to accomplish; the brain-computer interface ‘understands’ your intention on the basis of your brain activity and translates it into output on a computer.

For example, it is possible with currently technology to type letters into a word processor using thoughts alone. You simply concentrate on the letter you wish to type and it will appear on a computer screen.1 If you have a severe motor disability, brain-computer interfacing might allow you to do things that would otherwise be impossible, thereby enhancing your quality of life. You could potentially control a computer cursor, for example, or use a word processor to access the Internet and various forms of environmental control, such as light, temperature and entertainment. Another possible use relates to prosthetic limbs: if the BCI is connected to a prosthetic arm, you might be able to move that limb with your brain signals. A third area where brain-computer interfacing could also be used is in controlling a motorised wheelchair.2
Brain-Computer Interface

It may even be possible to use brain-computer interfacing in a rehabilitative way, to restore motor functions.3 This is done by combining a brain-computer interface (BCI) technology with a mechanical brace to physically manipulate the stroke affected limb, along with the use of Motor Imagery (MI). MI refers to a process by which a person produces a mental picture of an intended motor task in the absence of physical motor output4; this process elicits corticomotor activation patterns similar to actual task performance. The concept is to use neurophysiologic signals during real-time motor imagery (MI) and to transform these signals into computer commands. These commands in turn drive the mechanical brace with the patient’s affected limb secured to it, allowing the brain to volitionally interact with its external environment. This process has the ability to affect neuro-plastic changes after a period of training in patients who have had a stroke, which is likely to facilitate functional gains during stroke rehabilitation.5

There are two different ways a brain-computer interface can record brain signals, each corresponding to a different level of invasiveness.6 The first – non-invasive – way uses a device that you place on your head like a cap. It reads off brain signals from your scalp. It is easy and safe but limited in terms of the frequency and resolution of brain signals it can pick up. The second – invasive – way requires implantation of electrode arrays, either at the cortical surface or within the brain. This method is better for picking up brain signals but there are concerns about safety, risk of tissue reaction and long-term recording stability. According to medical researchers Daly and Walpaw (2008), the kind of invasiveness suitable for you is dependent on personal circumstances:

‘At present, it seems probable that different recording methods will be useful for different applications, different users, or both.’7

  • Possible benefits of Brain-Computer Interface for stroke

    Brain-computer interface is mainly used to allow people with minimal muscle control to communicate. For example, if you have had a brainstem stroke and only have minimal eye movement control, most conventional communication aids will not be useful, as they require voluntary muscle control. A BCI, however, might allow you to use a computer or environmental controls.

    A second area where BCI could be used is in the rehabilitation of motor functions, e.g. as part of a therapy that ‘rewires’ sections of the brain to perform the motor functions formerly accomplished by the damaged part of the brain. By measuring brain signals with a BCI, patients can be trained to produce more normal brain activity. In this way, the brain can be conditioned to send out the right signals, even if the patient is not yet able to perform the action properly. Together with more conventional methods, e.g. repetitive movement of the affected limbs, this might restore and improve motor control.

    In one study a 43-year-old woman, who was 10 months post-stroke, underwent a non-invasive BCI enforced rehabilitation program, with some success.8 She was asked to move or to relax her index finger. The BCI could then read her brain signals and tell her if she had ‘intended’ the right action, even though she was not yet able to move her finger. After three weeks of training, this woman had regained some voluntary control of her finger.

    Another group treated a stroke patient with a combination of Brain-Computer Interface exercises and physiotherapy. Using sophisticated brain scans, they were able to show evidence of recovery and of the brain actually re-learning how to complete certain physical actions (brain plasticity). This was the first case study that showed a significant improvement in movement along with changes that could be identified through the brain scans, i.e. neuroimaging.9

    In addition, Varkuti et al. studied 6 stroke patients who underwent MI and BCI with robotic feedback. They compared this to 3 stroke patients who received robotic rehabilitation alone. The results showed that group who received both BCI and robotic feedback had a greater number of changes in functional connectivity. Both of these studies show that the brain can change (plasticity) as a result of BCI intervention after stroke.10

    Finally, the Annals of Neurology in 2013 reported a study that shows the positive impact BMI training can have on physiotherapy.  They explained how BMI training can significantly help to improve finger movements for those living with chronic stroke. They showed that these improvements were accompanied by changes in the brain as a pattern of cortical reorganization, i.e. neuroplasticity.11

  • Arguments against using Brain-Computer Interface for stroke

    There are two main issues with brain-computer interfaces. First, a BCI requires lots of training by the user and the calibration of the computer system. You must train your ability to focus on specific tasks in order to use the BCI, which can be a lengthy process. The BCI also requires constant calibration and technical support. Although the actual equipment is not very dear, the maintenance costs make the treatment time-consuming and expensive. Therefore, the treatment is not widely available at present. To reduce costs, the need for technical support must be minimised and the BCI systems easy to set up and use.12

    Second, because current BCIs depend upon visual stimuli and visual feedback, they require the user to be able to see and maintain gaze. If you do not have sufficient visual acuity or gaze stability, you will not be able to use a BCI. The development of systems using auditory rather that visual stimuli is being investigated.13

     A 2014 systematic review concluded that to date the evidence suggests some promise for the use of BCI to aid rehabilitation. It is still early days in terms of long-term effectiveness, and more clinical data on the long term effects are needed to support the current evidence. 14

     

     

  • Case histories

    Thought-controlled wheelchair in Japan


  • Notes and references

     

      1.  ‘Brain waves can ‘write’ on a computer in early tests, researchers show’. In Science Daily, 7 December 2009
      2. Thought-controlled wheelchair in Japan
      3. DalyJJ, Cheng R, Rogers J, et al. ‘Feasibility of a New Application of Non-invasive Brain Computer Interface (BCI): A Case Study of Training for Recovery of Volitional Motor Control After Stroke’. In Journal of Neurologic Physical Therapy, 2009, No. 33, Vol. 4, pp. 203-11
      4. Sharma N, Pomeroy VM, Baron JC. ‘Motor imagery: A backdoor to the motor system after stroke?’,  Stroke 2006;7:1941-1952.
      5. Wei-Peng Teo,, Effie Chew, ‘Is Motor-Imagery Brain-Computer Interface Feasible in Stroke Rehabilitation?’ PM&R, American Academy of Physical Medicine and Rehabilitation, 2014
      6. DalyJJ & Walpaw JR ‘Brain-computer interfaces in neurological rehabilitation’. In Lancet Neural, 2008, No. 7, pp. 1032-43, p. 1033.
      7. DalyJJ & Walpaw JR. ‘Brain-computer interfaces in neurological rehabilitation’. In Lancet Neural, 2008, No. 7, p. 1033
      8. DalyJJ, Cheng R, Rogers J, et al. 2009: The therapy involved is a combination of BCI and Functional Electrical Stimulation (FES).
      9. A. Caria, C. Weber, D. Brotz, A. Ramos, L. F. Ticini, A. Gharabaghi, C. Braun, and N. Birbaumer, “Chronic stroke recovery after combined BCI training and physiotherapy: a case report,” Psychophysiology, vol. 48, no. 4, pp. 578-582, 2011
      10. B. Varkuti, C. Guan, Y. Pan, K. S. Phua, K. K. Ang, C. W. K. Kuah, K. Chua, B. Ti Ang, N. Birbaumer, and R. Sitaram, “Resting state changes in functional connectivity correlate With movement recovery for BCI and robot-assisted upper-extremity training after stroke,” Neurorehabilitation and Neural Repair, vol. 27, no. 1, pp. 53-62, 2013.
      11. Leonardo G. Cohen MD3 and Niels Birbaumer PhD, ‘Brain–machine interface in chronic stroke rehabilitation: A controlled study’Annals of Neurology, Volume 74, Issue 1, 2013.
      12. DalyJJ & Walpaw JR. 2008: p. 1038.
      13. Nijboer F, Furdea A, Gunst I, et al. ‘An auditory brain-computer interface (BCI)’. In Journal of Neuroscience Methods, 2008, No. 167, pp. 43–50.
      14. Is Motor-Imagery Brain-Computer Interface Feasible in Stroke Rehabilitation? Wei-Peng Teo, Effie Chew, PM&R, American Academy of Physical Medicine and Rehabilitation, 2014.

Aviva Cohen is the author and CEO of Neuro Hero