Investigation of visuospatial attention for suitability as a control signal of a brain-computer interface

• Applicant: Dr.-Ing. Christoph Reichert
• Subject Area: Human Cognitive and Systems Neuroscience ; Cognitive, Systems and Behavioural Neurobiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521761873

Visuospatial attention is characterized by brain activations that prioritize attended target stimuli. If the target stimulus is located in the left or right periphery of the visual field, electroencephalography (EEG) can be used to uncover differences in the event-related potentials of both hemispheres, which typically occur in occipitoparietal areas. Because this signal, known as N2pc, is measured independently of eye movements, it is predestined to be used by patients with complete paralysis to control a brain-computer interface (BCI). To date, several approaches have been pursued to enable communication with locked-in patients using BCIs. However, visuospatial attention has not been considered so far for BCI-based communication suitable for severely paralyzed individuals. Approaches that decode selective attention based on auditory stimulation have resulted in comparatively limited success. In previous BCI implementations that use selective visual attention, good visual acuity as well as eye movements are required. In contrast, visuospatial attention does not depend on these prerequisites. Furthermore, our approach is independent of brain regions presumably affected by the disease, such as the motor cortex, which is commonly used in BCIs controlled by motor imagery. Building on recent studies we have published, the goal of our proposed project is to optimize the decoding accuracy in a BCI setting suitable for patients. In the first phase of the research project, we will investigate the influence of the predictability of the occurrence of a target stimulus and the characteristics of the interstimulus interval on decoding accuracy. Since patients with motor impairment, who cannot blink or move their eyes, most likely cannot recognize visual details, we will also investigate the influence of different degrees of visual impairment on decoding accuracy. A major goal of our project is to present visual stimuli independent of head position and gaze direction. Solving this problem is the key prerequisite for patients who cannot move and even have lost the ability to move their eyes. The studies will be carried out with laboratory-based and mobile EEG devices in healthy participants. At the end of the project, a test series will be performed with a group of ALS patients, using the determined optimal stimulation parameters and validating the transferability of the results to affected patients. The successful finalization of the project will result in new insights into the processing of visuospatial attention in the brain as well as in findings that permit the development of a communication device for completely paralyzed persons.

• DFG Programme: Research Grants