TY - JOUR T1 - P300-based brain-computer interface (BCI) event-related potentials (ERPs): People with amyotrophic lateral sclerosis (ALS) vs. age-matched controls. JF - Clin Neurophysiol Y1 - 2015 A1 - McCane, Lynn M A1 - Susan M Heckman A1 - Dennis J. McFarland A1 - Townsend, George A1 - Mak, Joseph N A1 - Sellers, Eric W A1 - Zeitlin, Debra A1 - Tenteromano, Laura M A1 - Jonathan Wolpaw A1 - Theresa M Vaughan KW - alternative and augmentative communication (AAC) KW - amyotrophic lateral sclerosis (ALS) KW - Brain-computer interface (BCI) KW - brain-machine interface (BMI) KW - electroencephalography (EEG) KW - event-related potentials (ERP) AB -

OBJECTIVE: Brain-computer interfaces (BCIs) aimed at restoring communication to people with severe neuromuscular disabilities often use event-related potentials (ERPs) in scalp-recorded EEG activity. Up to the present, most research and development in this area has been done in the laboratory with young healthy control subjects. In order to facilitate the development of BCI most useful to people with disabilities, the present study set out to: (1) determine whether people with amyotrophic lateral sclerosis (ALS) and healthy, age-matched volunteers (HVs) differ in the speed and accuracy of their ERP-based BCI use; (2) compare the ERP characteristics of these two groups; and (3) identify ERP-related factors that might enable improvement in BCI performance for people with disabilities.

METHODS: Sixteen EEG channels were recorded while people with ALS or healthy age-matched volunteers (HVs) used a P300-based BCI. The subjects with ALS had little or no remaining useful motor control (mean ALS Functional Rating Scale-Revised 9.4 (±9.5SD) (range 0-25)). Each subject attended to a target item as the items in a 6×6 visual matrix flashed. The BCI used a stepwise linear discriminant function (SWLDA) to determine the item the user wished to select (i.e., the target item). Offline analyses assessed the latencies, amplitudes, and locations of ERPs to the target and non-target items for people with ALS and age-matched control subjects.

RESULTS: BCI accuracy and communication rate did not differ significantly between ALS users and HVs. Although ERP morphology was similar for the two groups, their target ERPs differed significantly in the location and amplitude of the late positivity (P300), the amplitude of the early negativity (N200), and the latency of the late negativity (LN).

CONCLUSIONS: The differences in target ERP components between people with ALS and age-matched HVs are consistent with the growing recognition that ALS may affect cortical function. The development of BCIs for use by this population may begin with studies in HVs but also needs to include studies in people with ALS. Their differences in ERP components may affect the selection of electrode montages, and might also affect the selection of presentation parameters (e.g., matrix design, stimulation rate).

SIGNIFICANCE: P300-based BCI performance in people severely disabled by ALS is similar to that of age-matched control subjects. At the same time, their ERP components differ to some degree from those of controls. Attention to these differences could contribute to the development of BCIs useful to those with ALS and possibly to others with severe neuromuscular disabilities.

UR - http://www.ncbi.nlm.nih.gov/pubmed/25703940 ER - TY - JOUR T1 - Brain-computer interface (BCI) evaluation in people with amyotrophic lateral sclerosis. JF - Amyotroph Lateral Scler Frontotemporal Degener Y1 - 2014 A1 - McCane, Lynn M A1 - Sellers, Eric W A1 - Dennis J. McFarland A1 - Mak, Joseph N A1 - Carmack, C Steve A1 - Zeitlin, Debra A1 - Jonathan Wolpaw A1 - Theresa M Vaughan KW - Adult KW - Aged KW - Amyotrophic Lateral Sclerosis KW - Biofeedback, Psychology KW - brain-computer interfaces KW - Communication Disorders KW - Electroencephalography KW - Event-Related Potentials, P300 KW - Female KW - Humans KW - Male KW - Middle Aged KW - Online Systems KW - Photic Stimulation KW - Psychomotor Performance KW - Reaction Time AB - Brain-computer interfaces (BCIs) might restore communication to people severely disabled by amyotrophic lateral sclerosis (ALS) or other disorders. We sought to: 1) define a protocol for determining whether a person with ALS can use a visual P300-based BCI; 2) determine what proportion of this population can use the BCI; and 3) identify factors affecting BCI performance. Twenty-five individuals with ALS completed an evaluation protocol using a standard 6 × 6 matrix and parameters selected by stepwise linear discrimination. With an 8-channel EEG montage, the subjects fell into two groups in BCI accuracy (chance accuracy 3%). Seventeen averaged 92 (± 3)% (range 71-100%), which is adequate for communication (G70 group). Eight averaged 12 (± 6)% (range 0-36%), inadequate for communication (L40 subject group). Performance did not correlate with disability: 11/17 (65%) of G70 subjects were severely disabled (i.e. ALSFRS-R < 5). All L40 subjects had visual impairments (e.g. nystagmus, diplopia, ptosis). P300 was larger and more anterior in G70 subjects. A 16-channel montage did not significantly improve accuracy. In conclusion, most people severely disabled by ALS could use a visual P300-based BCI for communication. In those who could not, visual impairment was the principal obstacle. For these individuals, auditory P300-based BCIs might be effective. VL - 15 UR - http://www.ncbi.nlm.nih.gov/pubmed/24555843 IS - 3-4 ER -