There are numerous diseases that can lead to a complete loss of muscle control in the body, such as Amyotrophic Lateral Sclerosis (ALS). In many cases, these individuals can reach a state known as Locked-In Syndrome (LIS), where they can only move their eyes, or Total Locked-In Syndrome (CLIS) if they also lose control of their gaze.

While some interaction systems allow some of these patients to communicate, such as those based on eye-trackers, in other cases, the only alternative is to provide the patient with a non-muscular channel using Brain-Computer Interfaces (BCI systems), which is the focus of this project. BCI systems analyze the electroencephalographic (EEG) signal to generate commands that are sent to a computer to control various devices, such as a communication system. These systems are often referred to as BCI Spellers and are typically controlled by visual attention to different stimuli displayed on a screen (usually letters of the alphabet randomly flashing), achieving good results. However, they often require some level of gaze control to pay attention to symbols or letters located away from the center of the screen. In the case of patients who have lost gaze control due to the progression of the disease, as is the case with CLIS patients, it is necessary to explore other alternatives.

One of these less-studied alternatives is based on visual stimuli as well, presenting keyboard symbols one by one in the center of the screen. This type of serial stimulus presentation paradigm is known as Rapid Serial Visual Presentation (RSVP). The first goal of the project is to conduct research to improve communication systems based on this paradigm. In particular, the aim is to study new forms of visual stimulation that result in more easily detectable changes in the EEG signal, thus enhancing system performance and communication capabilities.

In cases of patients with vision problems or in an advanced state of the disease, such as CLIS patients, it is necessary to turn to a less explored second alternative, which is auditory BCI systems. These systems have the advantage of not relying on the visual channel as they use auditory stimuli. The second goal of the project is to investigate proposals for systems that provide a minimum level of communication to CLIS or LIS patients who do not have ocular control.

To transfer BCI-based technology from the laboratory to domestic use, these systems must be compact, cost-effective, and user-friendly. In this regard, the third goal of this project is to develop a compact and low-cost Augmentative and Alternative Communication System (AAC), configurable and adaptable to the patient’s needs, to run on a portable hardware platform such as a tablet. Additionally, this system could be used with a low-cost eye-tracking device and through touch, thereby extending its use to patients in a less advanced stage of the disease.