Brain-Computer Interface (BCI)

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.

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.

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.