Abstract
Our objective was to investigate the capacity to control a P3-based brain-computer interface (BCI) device for communication and its related (temporal) attention processing in a sample of amyotrophic lateral sclerosis (ALS) patients with respect to healthy subjects. The ultimate goal was to corroborate the role of cognitive mechanisms in event-related potential (ERP)-based BCI control in ALS patients. Furthermore, the possible differences in such attentional mechanisms between the two groups were investigated in order to unveil possible alterations associated with the ALS condition. Thirteen ALS patients and 13 healthy volunteers matched for age and years of education underwent a P3-speller BCI task and a rapid serial visual presentation (RSVP) task. The RSVP task was performed by participants in order to screen their temporal pattern of attentional resource allocation, namely: (i) the temporal attentional filtering capacity (scored as T1%); and (ii) the capability to adequately update the attentive filter in the temporal dynamics of the attentional selection (scored as T2%). For the P3-speller BCI task, the online accuracy and information transfer rate (ITR) were obtained. Centroid Latency and Mean Amplitude of N200 and P300 were also obtained. No significant differences emerged between ALS patients and Controls with regards to online accuracy (p = 0.13). Differently, the performance in controlling the P3-speller expressed as ITR values (calculated offline) were compromised in ALS patients (p < 0.05), with a delay in the latency of P3 when processing BCI stimuli as compared with Control group (p < 0.01). Furthermore, the temporal aspect of attentional filtering which was related to BCI control (r = 0.51; p < 0.05) and to the P3 wave amplitude (r = 0.63; p < 0.05) was also altered in ALS patients (p = 0.01). These findings ground the knowledge required to develop sensible classes of BCI specifically designed by taking into account the influence of the cognitive characteristics of the possible candidates in need of a BCI system for communication.
Highlights
The non-invasive brain-computer interface (BCI) based on the visual event-related potential (ERP) known as P300 (P3; Farwell and Donchin, 1988) is by far the most extensively investigated BCI system to enhance or even allow communication when this latter is severely compromised due to different neurological disorders (Kleih et al, 2011; Riccio et al, 2016)
The amyotrophic lateral sclerosis (ALS) and Control groups did not show significant differences as regard demographic characteristics (Student’s T-test; t(24) = 1.6; p = 0.13 and t(24) = 0.17; p = 0.85 for age and ‘‘years of formal education’’, respectively) and clinical assessment focused on selective attention (SA; error scores, χ 2 = 1.96; p = 0.16), working memory (WM; errors χ 2 = 3.29; p = 0.07) and executive functions (EF; χ 2 = 0.119; p = 0.729)
We focused on the attention processing involved in the delivering of the visual BCI stimulation paradigm, in order to further (Riccio et al, 2013) elucidate if and how such cognitive abilities would be altered in ALS patients and eventually would account for patients’ BCI control capacity
Summary
The non-invasive brain-computer interface (BCI) based on the visual event-related potential (ERP) known as P300 (P3; Farwell and Donchin, 1988) is by far the most extensively investigated BCI system to enhance or even allow communication when this latter is severely compromised due to different neurological disorders (Kleih et al, 2011; Riccio et al, 2016). A number of studies reported that ALS patients can communicate by using a P3-based BCI (Marchetti et al, 2013) with stable performance over time (Sellers and Donchin, 2006; Nijboer et al, 2008; Silvoni et al, 2013). McCane et al (2015) reported no significant differences in BCI accuracy between ALS patients and healthy age- (but not years of education-) matched subjects. They found differences in the target-related ERPs characteristics: the ALS group presented a higher N2 wave peak amplitude and a latency delay in N2, P3 and late negativity (LN) with respect to the control group. Further investigations are needed on the possible impairment/alteration of brain processing in response to external inputs (such as visual stimuli) delivered within a BCI framework of stimulation to eventually unveil whether and how they could influence the BCI control
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