News Feed – fNIRS Brain Computer Interface provides potential avenue to communicate with Complete Locked-in State Patients
Complete Locked-In State (CLIS) is characterized by a person’s deterioration of all motor functions, but the retention of psychological and emotional capabilities. Traditional methods of attempted communication with people that have CLIS usually involves a variety of brain computer interface techniques. Some of these techniques have involved invasive measures such as implanted electrodes, while others have relied on non-invasive brain imaging technologies such as functional magnetic resonance imaging (fMRI) or electroencephalography (EEG). A recent study published in PLOS Biology on January 31st, 2017, showcased a new method to communicate with four CLIS patients using functional near-infrared spectroscopy (fNIRS) 1, 2 and gives hope in restoring some motor functionality to those with the condition 3.
The fNIRS communication technique involved asking CLIS patients yes or no questions, and at the same time using a non-invasive brain-computer interface that utilized fNIRS combined with EEG to measure hemodynamic responses and electrical activity in the brain to determine a positive or negative response. Some of the questions posed to the patients included “Your husband’s name is Joachim?” and, perhaps more importantly, “Are you happy?”. The latter question received a reply of “yes” from all four of the patients, and was repeatedly asked over weeks of questioning. In response to the question about happiness, one of the lead researchers on the study, Professor Neils Birbaumer of the Wyss Center for Bio Neuroengineering in Geneva, Switzerland, remarked, “We were initially surprised at the positive responses when we questioned the four completely locked-in patients about their quality of life. All four had accepted artificial ventilation to sustain their life, when breathing became impossible; thus, in a sense, they had already chosen to live. What we observed was that as long as they received satisfactory care at home, they found their quality of life acceptable. It is for this reason, if we could make this technique widely clinically available, it could have a huge impact on the day-to-day life of people with completely locked-in syndrome.”
Each of the four patients featured in the study suffered from amyotrophic lateral sclerosis (ALS), a motor neuron disease characterized by progressive degeneration of motor neurons in the brain, brainstem, and spinal cord. Degeneration of the upper and lower motor neurons leads to spasticity, impaired reflexes, muscle fatigue, muscle weakness, and eventually atrophy. ALS eventually leads to CLIS after given a sufficient amount of time to progress 4. During the progression of the disease, 80-95% of people with ALS are unable to meet their daily communication needs using natural speech 5. While the patient still has a reliable means of communication, ALS compromises both respiratory and bulbar functions. Changes in speech patterns or speaking rate typically occur before a decrease in speech intelligibility 6, 7. The severity of the condition requires that the patient chooses whether to opt for a life with artificial respiration. Clearly, providing those affected with ALS some portion of the motor functionality that they have lost would be a remarkable step forward.
Professor Birbaumer expounded on the impact of the study, and its relevance in future applications stating, “Restoring communication for completely locked-in patients is a crucial first step in the challenge to regain movement. The Wyss Center plans to build on the results of this study to develop clinically useful technology that will be available to people with paralysis resulting from ALS, stroke, or spinal cord injury. The technology used in the study also has broader applications that we believe could be further developed to treat and monitor people with a wide range of neuro-disorders.”
Fig 1. The averaged relative change in O2Hb corresponding to “yes” and “no” sentence interstimuli interval (ISI).
1. Ayaz, H., Shewokis, P. A., Bunce, S. & Onaral, B. An optical brain computer interface for environmental control. 2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society 6327–6330 (2011). doi:10.1109/IEMBS.2011.6091561
2. Sitaram, R. et al. Temporal classification of multichannel near-infrared spectroscopy signals of motor imagery for developing a brain–computer interface. Neuroimage 34, 1416–1427 (2007).
3. Chaudhary, U., Xia, B., Silvoni, S., Cohen, L. G. & Birbaumer, N. Brain–Computer Interface–Based Communication in the Completely Locked-In State. PLOS Biol. 15, e1002593 (2017).
4. Chou, S. M. & Norris, F. H. Issues & Opinions: Amyotrophic lateral sclerosis: Lower motor neuron disease spreading to upper motor neurons. Muscle Nerve 16, 864–869 (1993).
5. Beukelman, D., Fager, S. & Nordness, A. Communication support for people with ALS. Neurology Research International 2011, 6 (2011).
6. Ball, L. J., Beukelman, D. R. & Pattee, G. L. Acceptance of Augmentative and Alternative Communication Technology by Persons with Amyotrophic Lateral Sclerosis. Augment. Altern. Commun. 20, 113–122 (2004).
7. Yunusova, Y. et al. Kinematics of Disease Progression in Bulbar ALS. J. Commun. Disord. 43, 6 (2010).
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