Abstract
To describe results of training and 1-year follow-up of brain-communication in a larger group of early and middle stage amyotrophic lateral sclerosis (ALS) patients using a P300-based brain–computer interface (BCI), and to investigate the relationship between clinical status, age and BCI performance. A group of 21 ALS patients were tested with a BCI-system using two-dimensional cursor movements. A four choice visual paradigm was employed to training and test the brain-communication abilities. The task consisted of reaching with the cursor one out of four icons representing four basic needs. Five patients performed a follow-up test 1 year later. The clinical severity in all patients were assessed with a battery of clinical tests. A comparable control group of nine healthy subjects was employed to investigate performance differences. Nineteen patients and nine healthy subjects were able to achieve good and excellent cursor movements' control, acquiring at least communication abilities above chance level; during follow-up the patients maintained their BCI-skill. We found mild cognitive impairments in the ALS group which may be attributed to motor deficiencies, while no relevant correlation has been found between clinical data and BCI performance. A positive correlation between age and the BCI-skill in patients was found. Time since training acquisition and clinical status did not affect the patients brain-communication skill at early and middle stage of the disease. A brain-communication tool can be used in most ALS patients at early and middle stage of the disease before entering the locked-in stage.
Highlights
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with degeneration of motor neurons and characterized by progressive muscle weakness and atrophy
We found mild cognitive impairments in the amyotrophic lateral sclerosis (ALS) group which may be attributed to motor deficiencies, while no relevant correlation has been found between clinical data and brain–computer interface (BCI) performance
In the first comparison a mild cognitive deficit in ALS was evidenced by significant differences in tests mainly related to the attentive and executive functions: semantic verbal fluency (U = 28.5, p = 0.001), phonemic verbal fluency (U = 42, p = 0.011), Raven’s coloured matrices (U = 53, p = 0.038), Wisconsin card sorting test (WCST) cat. (U = 48.5, p = 0.02)
Summary
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with degeneration of motor neurons and characterized by progressive muscle weakness and atrophy. A wide range of brain signals could be used for this purpose, such as slow cortical potentials (SCPs, Kuebler et al, 1998), sensorimotor rhythms (SMRs, Wolpaw et al, 1991), steady state visual evoked potentials (Cheng et al, 2002), near infrared spectroscopy (Coyle et al, 2004), and event-related potentials (ERPs, Farwell and Donchin, 1988). Some of these studies involved ALS patients, mainly in the late stage of the disease, in order to offer them a reliable instrument for communication (Kübler and Birbaumer, 2008). The BCI technology was successfully used for movement restoration (Buch et al, 2008; Hochberg et al, 2006; MüllerPutz and Pfurtscheller, 2008; Pfurtscheller et al, 2003)
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