## 4 Discussion
The implementation of BCI technology for patients in LIS allows experimenters to directly question a patient's comprehension on how to use the system, and possibly facilitates them becoming proficient users before entering CLIS. BCI studies starting when the patient enters LIS would also allow a longitudinal assessment of the hypothesis of the extinction of goal-directed thinking [15; 31]. This hypothesis states that there is a reduction in arousal, vigilance, and working memory in patients in CLIS due to the lack of social-cognitive interaction. The continuous use of BCIs would allow uninterrupted communication, even after losing eye movements, with family members and caretakers, preventing a decline in executive function. In [6], a patient who progressed from LIS to CLIS retained the ability to use the BCI acquired in LIS. Additionally, introducing the interface before entering in CLIS would enable patients to offer valuable insights, providing feedback on interface design, and express any concerns or doubts about how the system operates, which were not possible to ascertain in our study. This would enable improved personalization. The introduction of BCI for assistive contexts before an ALS patient even reaches LIS has been explored in [33; 34] showing that the mental strategies used can become helpful in translating these mental strategies when the patient reaches more advanced states. Thus, early BCI introduction in earlier stages of ALS, even in LIS, could help prolong patients' communication capabilities. Future work is expected to include larger-scale longitudinal studies, with the inclusion of both LIS and CLIS patients, to address the aforementioned aspects and achieve a more optimized combination of stimulation strategies and classification algorithms tailored to patients' specific needs. Furthermore, BCI sessions with patients should occur in periods when the patients are known to be awake/vigilant. It is essential to find biomarkers of patients' vigilance levels as well as performance predictors. With these goals, an automatic vigilance detector is underway towards implementation. Additionally, shorter calibration sessions are required to reduce patient fatigue. Within our group, efforts have been made to reduce calibration times, albeit so far only having been tested with healthy participants [28]. Conceptualization, G.P. and R.B. ; methodology, G.P. and R.B. ; software, G.P. and R.B. ; validation, G.P. and R.B. ; formal analysis, G.P., R.B., M.C.-B., E.G. and U.J.N. ; writing--original draft preparation, R.B. and G.P. ; writing--review and editing, R.B., M.C.-B., E.G., U.J.N. and G.P. ; funding acquisition, G.P. and U.J.N. All authors have read and agreed to the published version of the manuscript. This research was funded by the Portuguese Foundation for Science and Technology (FCT) under Grants ISR-UC UIDB/00048/2020 (doi: 10.54499/UIDB/00048/2020), B-RELABLE: PTDC/EEI-AUT/30935/2017 and BCI4 ALL2024. [PERSON] was supported by the FCT Ph.D. scholarship 2023.03995.BD (doi: 10.54499/2023.03995.BD). The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee for Health of the University Hospital Center of S. Joao, Porto (CHUS) (protocol nr. 162/2023). Informed Consent Statement: Informed consent was obtained from all subjects or from a legal representative of the subjects involved in the study. The raw data supporting the conclusions of this article will be made available by the authors on request. The authors would like to thank the patient's family for their availability and support during the experiments. The authors declare no conflicts of interest.