Non-invasive EEG-based Continuous Three-dimensional Brain-Computer Interface

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SUMMARY Of the roughly 5 million cases of paralysis in the United States alone, approximately 1.4 million of these are due to spinal cord injury (SCI). In moderate to extreme cases of SCI, patients must rely significantly on others for care ranging from feeding to bathing. While these individuals hold a strong desire for increased autonomy, very few treatment options currently exist. In recent years, the implantation of invasive neural brain computer interfaces (BCI) has shown promise in increasing patient independence by providing an alternative non- physiological communication channel for the brain. However, these BCIs come with substantial short and long term health risks, as the surgical implantation is in itself a risk, and is accompanied by risks of immune responses and infections. In contrast, while noninvasive electroencephalography (EEG) BCIs pose no major risks to the individuals, they are limited by their spatial resolution. Only through recent advancements in novel spatial filters, unique, intuitive tasks, and complex training paradigms have EEG BCIs been extended to three-dimensional discrete task virtual cursor control and two-dimensional continuous virtual cursor and robotic arm control. The research proposed here aims to further investigate the dynamics and tuning properties of the novel control signals, better understand the effects on cognitive load of combined cognitive tasks during noninvasive BCI, and combine the two advances for the training and demonstration of practical 3D continuous virtual cursor control. The main hypothesis of this work is that by combining our understanding of motor imagery and further developing our neuroscientific understanding of overt-spatial attention (OSA) as an intuitive control signal, individuals will be able to robustly, continuously control a virtual cursor in three dimensions utilizing noninvasive EEG BCI. In order to accomplish this, two specific aims are proposed. Firstly, I will investigate the spatial organization of OSA, as well as its dependence on user head orientation using high density EEG. I will identify spatial maps using inverted encoding models, inspired and guided by knowledge gained from invasive neuroscientific studies delineating the tuning profiles of visual spatial attention, to predict a user’s locus of attention in space given a subject’s frame of reference. I will additionally determine via a head fixation and rotation experiment, whether the representation of overt spatial attention is head or body centric. Secondly, I will establish a novel three dimensional continuous pursuit training paradigm as a testing ground for evaluating 3D control, and will investigate the effects multimodal control strategies have on cognitive load and control strength. The successful completion of the proposed work will have a significant effect on the BCI community, particularly by contributing towards the translation of non-invasive technologies towards clinical use and improving the quality of life of SCI patients.