Periodic Reporting for period 1 - DOC-Stim (Communication and rehabilitation for people with Disorders of consciousness via Brain-Computer Interfaces)
Période du rapport: 2020-07-01 au 2022-06-30
Persons with a disorder of consciousness (DOC) have little or no ability to interact with people and devices. They are unable to control voluntary movement, and hence they cannot speak, blink, use devices for communication, or otherwise convey their needs and desires. The uploaded figure shows disorders of consciousness classified on a two-dimensional scale of arousal and awareness. Arousal is also described as wakefulness or vigilance. Awareness is the level of perception and recognition of the person himself and of the environment. People in coma have no arousal and no awareness and could be found in the bottom left corner of the figure. In the top right corner, one can find people in the locked-in syndrome (LIS). People with minimal consciousness state (MCS) or unresponsive wakefulness (UWS) are the most challenging in terms of diagnoses and treatment. The arousal of these people could be very high, although the awareness is not existent (UWS) or at a low level (MCS).
Research from our group and others has shown that up to 42% of patients in top hospitals are misdiagnosed, when using behavioural assessment techniques. This misdiagnosis can, among other problems, discourage doctors and families from even trying to communicate with the patients. It has been shown that electroencephalograhpy (EEG) can be useful for the diagnosis. Activations of brain regions can be assessed in real-time, as well as the brains' reactions to outer stimuli. Such methods and devices based on real-time EEG can help re-assess DOC patients’ cognitive functions and even provide basic communication for them. Other work found that new tools to noninvasively monitor and stimulate brain activity could substantially improve recovery of persons with stroke or other disabilities. EEG data can detect each patient’s motor imagery and thereby influence multimodal feedback in real-time.
This project worked on developing new EEG based assessment and rehabilitation tools for DOC patients. We created a new system that will be used to collect data with DOC patients. We analyzed the resulting data to develop new knowledge and contribute to improved tools that therapists and physicians can use.
Research from our group and others has shown that up to 42% of patients in top hospitals are misdiagnosed, when using behavioural assessment techniques. This misdiagnosis can, among other problems, discourage doctors and families from even trying to communicate with the patients. It has been shown that electroencephalograhpy (EEG) can be useful for the diagnosis. Activations of brain regions can be assessed in real-time, as well as the brains' reactions to outer stimuli. Such methods and devices based on real-time EEG can help re-assess DOC patients’ cognitive functions and even provide basic communication for them. Other work found that new tools to noninvasively monitor and stimulate brain activity could substantially improve recovery of persons with stroke or other disabilities. EEG data can detect each patient’s motor imagery and thereby influence multimodal feedback in real-time.
This project worked on developing new EEG based assessment and rehabilitation tools for DOC patients. We created a new system that will be used to collect data with DOC patients. We analyzed the resulting data to develop new knowledge and contribute to improved tools that therapists and physicians can use.
Within DOC-Stim we developed three cognitive protocols for DOC patients and one movement protocol. One using vibrotactile stimulation, one with functional electric (FES) stimulation and the third one with transcranial direct current stimulation (tDCS).
Vibrotactile protocol:
The vibrotactile stimulation protocol uses 7 tactile stimulators that can be distributed all over the patient’s body. The protocol is for assessment and communication of a patient. While the protocol is running, the seven stimulators will generate short vibration bursts in randomized order. By counting each vibration burst on the selected target stimulator, the processing in the human’s brain will create an EEG pattern that can be detected by the BCI, hence the system knows on which stimulator the patient was focusing on.The protocol has two modes: assessment mode and communication mode. The first one is for assessing the status of consciousness of a patient, the second to generate an easy means of communication for people without any voluntary motor control. During an assessment session a user is told on which target stimulator he or she shall focus on. If the system detects that the patient is focusing on those locations, it can be concluded that she or he is able to understand and follow instructions, hence there is consciousness in the patient. If an assessment run was successful one can continue to a communication run. In the communication mode, the system does not tell the user on which stimulator he or she shall focus, instead the patient’s voluntary selection of one stimulator expresses the answer she or he wants to give. This means, before asking a question, the experimenters gives each of the two target stimulators a distinct meaning, e.g. “YES” or “NO” or “Monday” or “Tuesday”. Now, the experimenter explains the question and the two answering options to the patient, for example the question could be “Should I switch on the radio?”. The answer could be to focus on the stimuli one feels on the left hand for the answer “YES, please switch on the radio”, or focus on the stimuli one feels on the right hand for “NO, please don’t”.
tDCS protocol_
tDCS stands for transcranial direct current stimulation and is one of DOC-Stim’s new stimulation approaches for rehabilitation of DOC patients. A meta- analysis revealed just in November 2020 that tDCS improves attention/vigilance and shows a small trans-diagnostic effect on working memory. This paradigm makes use of these effects. tDCS provides a constant current for several minutes between two selected electrode positions. Depending on the polarity it can increase or decrease the excitability of neurons, and hence can increase or
decrease learning and rehabilitation. With the DOC-Stim system stimulation can be done during or before running protocols for example the new vibrotactile one. By using the stimulation, the rehabilitation effect will be increased.
Resting state EEG protocol:
The resting state analysis is for assessment only, not for rehabilitation. Several studies showed that biomarkers from resting state EEG can provide useful information about the status of a patient. After the acquisition of ten minutes of resting state EEG, the Delta Alpha Ratio (DAR) and the Power Ratio Index (PRI) are calculated. In Task 3.7 we show correlations between functional scales and those parameters.
Movement protocol:
The movement protocol is for rehabilitation of DOC patients. If a patient tries to perform motor movements, the according brain areas will be active, no matter if the motor movement is really performed or not. Some scientists speculate that the motor output in some patients is blocked, this means that the function of motor areas in the brain is intact, but the motor commands don’t reach the periphery. With the BCI technology we track the intention to perform movements and close the feedback loop by using FES to contract the peripheral muscles. That way, the information about the movements gets fed back via afferent nervous pathways to the motor cortex. This rehabilitation protocol shall improve the rehabilitation success of DOC patients. During a session a patient is asked to try 80 movements and will receive feedback if brain areas are activated.
Vibrotactile protocol:
The vibrotactile stimulation protocol uses 7 tactile stimulators that can be distributed all over the patient’s body. The protocol is for assessment and communication of a patient. While the protocol is running, the seven stimulators will generate short vibration bursts in randomized order. By counting each vibration burst on the selected target stimulator, the processing in the human’s brain will create an EEG pattern that can be detected by the BCI, hence the system knows on which stimulator the patient was focusing on.The protocol has two modes: assessment mode and communication mode. The first one is for assessing the status of consciousness of a patient, the second to generate an easy means of communication for people without any voluntary motor control. During an assessment session a user is told on which target stimulator he or she shall focus on. If the system detects that the patient is focusing on those locations, it can be concluded that she or he is able to understand and follow instructions, hence there is consciousness in the patient. If an assessment run was successful one can continue to a communication run. In the communication mode, the system does not tell the user on which stimulator he or she shall focus, instead the patient’s voluntary selection of one stimulator expresses the answer she or he wants to give. This means, before asking a question, the experimenters gives each of the two target stimulators a distinct meaning, e.g. “YES” or “NO” or “Monday” or “Tuesday”. Now, the experimenter explains the question and the two answering options to the patient, for example the question could be “Should I switch on the radio?”. The answer could be to focus on the stimuli one feels on the left hand for the answer “YES, please switch on the radio”, or focus on the stimuli one feels on the right hand for “NO, please don’t”.
tDCS protocol_
tDCS stands for transcranial direct current stimulation and is one of DOC-Stim’s new stimulation approaches for rehabilitation of DOC patients. A meta- analysis revealed just in November 2020 that tDCS improves attention/vigilance and shows a small trans-diagnostic effect on working memory. This paradigm makes use of these effects. tDCS provides a constant current for several minutes between two selected electrode positions. Depending on the polarity it can increase or decrease the excitability of neurons, and hence can increase or
decrease learning and rehabilitation. With the DOC-Stim system stimulation can be done during or before running protocols for example the new vibrotactile one. By using the stimulation, the rehabilitation effect will be increased.
Resting state EEG protocol:
The resting state analysis is for assessment only, not for rehabilitation. Several studies showed that biomarkers from resting state EEG can provide useful information about the status of a patient. After the acquisition of ten minutes of resting state EEG, the Delta Alpha Ratio (DAR) and the Power Ratio Index (PRI) are calculated. In Task 3.7 we show correlations between functional scales and those parameters.
Movement protocol:
The movement protocol is for rehabilitation of DOC patients. If a patient tries to perform motor movements, the according brain areas will be active, no matter if the motor movement is really performed or not. Some scientists speculate that the motor output in some patients is blocked, this means that the function of motor areas in the brain is intact, but the motor commands don’t reach the periphery. With the BCI technology we track the intention to perform movements and close the feedback loop by using FES to contract the peripheral muscles. That way, the information about the movements gets fed back via afferent nervous pathways to the motor cortex. This rehabilitation protocol shall improve the rehabilitation success of DOC patients. During a session a patient is asked to try 80 movements and will receive feedback if brain areas are activated.
GTEC has the only available product that is using BCI technology for assessment and communication with DOC patients. The DOC-Stim project delivered new protocols for this system, incorporating new stimulation methods. The stimulation with tDCS and FES results in enhanced rehabilitation of patients, the new vibrotactile protocol enables better communication accuracy and adds the third answering option called indecisive answer.
It has been shown that 43% of patients diagnosed as unresponsive wakefulness are reclassified as (at least) minimally conscious when re-assessed by expert teams. The DOC-Stim system offers new methods for detection of consciousness in unresponsive persons and can reduce the misclassification of patients. It further fosters rehabilitation effort for patients who are at least in minimal conscious state to regain a normal or more normal life. Those features of the DOC-Stim system could have potentially big positive socio-economic and societal implications.
It has been shown that 43% of patients diagnosed as unresponsive wakefulness are reclassified as (at least) minimally conscious when re-assessed by expert teams. The DOC-Stim system offers new methods for detection of consciousness in unresponsive persons and can reduce the misclassification of patients. It further fosters rehabilitation effort for patients who are at least in minimal conscious state to regain a normal or more normal life. Those features of the DOC-Stim system could have potentially big positive socio-economic and societal implications.