The general objectives of this project focus on conducting research and application development tasks aimed at improving the quality of life for patients with Locked-In Syndrome, such as some ALS patients. It is important to note that while there may be research areas with a broader impact in terms of a larger number of potential users, it is equally important to undertake research tasks that contribute to the development of applications for a smaller user base, especially considering the significant benefit they can provide in the absence of technical aids that enable communication for these individuals. Furthermore, research in the field of BCI systems is currently booming, with the potential for numerous contributions from this project.

The specific objectives set forth in this project are three. Each of these objectives will include partial objectives. The following briefly describes these objectives, with more detailed information on their achievement provided in the methodology.

OBJECTIVE 1: Study and proposal of communication interfaces to enhance the performance of visual BCI systems for patients without oculomotor control.

Parameters related to visual stimuli in a BCI-P300 speller system based on the RSVP paradigm have been underexplored. Some of these parameters include the size of the stimuli, the distance between them, or the size of the display surface; parameters that have been studied in the Row-Column Paradigm (RCP) but whose effects may differ in RSVP, as demonstrated by the research team in a recent study [Fern21]. This objective aims to investigate these variables to understand how they affect the performance of these systems designed for users without oculomotor control. Along the same lines, research will also be conducted on new proposals for visual stimuli based on color, images, and a particular focus on 3D stimulation due to its potential advantages in RSVP-based systems, as evidenced outside the BCI field or with the use of RCP. Finally, to enhance the performance of a BCI system based on the RSVP paradigm, which is hindered by the need to present stimuli one by one in series, work will be done on designing new interfaces that include text predictors and/or keyboards that require fewer stimuli, such as the T9 predictor used in mobile phones. Solutions like these have not yet been addressed in the RSVP modality and would undoubtedly increase the binary rate of these systems. Various proposals for this objective will be worked on using the UMA-BCI Speller platform.

To achieve this objective, three partial objectives are established:

Objective 1.1 – Study of parameters related to the presentation and distribution of visual stimuli in a BCI-P300 for users without oculomotor control.

Objective 1.2 – Study of the effects of different types of stimuli applied to a BCI-P300 for users without oculomotor control.

Objective 1.3 – Study and proposal of new interfaces to improve the performance of a BCI-P300 speller applied to users without oculomotor control.

OBJECTIVE 2: Study of stimulation paradigms that improve stimulus discrimination in an auditory BCI system.

In some extreme cases caused by the progression of the disease, the patient’s visual channel can be affected, as is the case with CLIS patients. In such cases, the only alternative to establish a communication channel is to use brain-computer interfaces based on auditory stimuli. To date, very few studies have addressed this issue due to its complexity. It is necessary to study control strategies that facilitate communication for these patients, even if it is very basic, such as responding Yes/No to questions. The contribution to this second objective will be purely research-based and will continue the research line initiated by the research team in the SICCAU project, which aims to keep the user’s attention active to prevent a drop in performance. Different paradigms and sets of stimuli will be studied to find those that are more easily differentiable by the user and, at the same time, go unnoticed when not attended to.

Two partial objectives are proposed in this objective 2:

Objective 2.1 – Study of solutions based on auditory BCIs.

Objective 2.2 – Implementation and testing of an auditory BCI focused on patients without oculomotor control.

OBJECTIVE 3: Development of a low-cost Augmentative and Alternative Communication System for individuals in a locked-in state.

This third objective arises from the absence of a communication system based on a BCI-P300 speller that is flexible, easy to configure, adaptable to each user, compact, and cost-effective. Existing systems are developed for specific purposes, offer very few configuration options, are challenging to operate, require expensive data acquisition systems, and must run on a computer, limiting their use in clinical or home settings. To develop the proposed system, the UMA-BCI Speller application already developed in the LICOM project will serve as a starting point. This application’s main function is to provide a flexible and easy-to-configure communication system, allowing for the creation of templates based on pictograms, which is a fundamental requirement for the development of an AAC system adaptable to each patient’s unique needs. In addition, UMA-BCI Speller incorporates both RCP (with text prediction) and RSVP modes, as well as a speech synthesizer, making it a highly versatile and user-friendly application. To achieve a compact system, the application will run on a tablet. As for the data acquisition system, the goal is for it to be cost-effective and easy to set up. While the primary purpose is for it to be controlled through brain activity, the developed system will expand access modes, allowing control through an eye-tracker for patients with remaining oculomotor control and even through touch for patients with some remaining motor function.

Three partial objectives are established to achieve this objective 3:

Objective 3.1 – Development of a mobile application (App) based on UMA-BCI Speller.

Objective 3.2 – Integration of different access modes: EEG, gaze tracking, touch.

Objective 3.3 – Testing of the complete system and development of a final product.