Predicting mental imagery based BCI performance from personality, cognitive profile and neurophysiological patterns

Mental-Imagery based Brain-Computer Interfaces (MI-BCIs) allow their users to send commands to a computer using their brain-activity alone (typically measured by ElectroEncephaloGraphy— EEG), which is processed while they perform specific mental tasks. While very promising, MI-BCIs remain barely used outside laboratories because of the difficulty encountered by users to control them. Indeed, although some users obtain good control performances after training, a substantial proportion remains unable to reliably control an MI-BCI. This huge variability in user-performance led the community to look for predictors of MI-BCI control ability. However, these predictors were only explored for motor-imagery based BCIs, and mostly for a single training session per subject. In this study, 18 participants were instructed to learn to control an EEG-based MI-BCI by performing 3 MI-tasks, 2 of which were non-motor tasks, across 6 training sessions, on 6 different days. Relationships between the participants’ BCI control performances and their personality, cognitive profile and neurophysiological markers were explored. While no relevant relationships with neurophysiological markers were found, strong correlations between MI-BCI performances and mental-rotation scores (reflecting spatial abilities) were revealed. Also, a predictive model of MI-BCI performance based on psychometric questionnaire scores was proposed. A leave-one-subject-out cross validation process revealed the stability and reliability of this model: it enabled to predict participants’ performance with a mean error of less than 3 points. This study determined how users’ profiles impact their MI-BCI control ability and thus clears the way for designing novel MI-BCI training protocols, adapted to the profile of each user

Fine motor control in using pen for writing and copying: in the impaired and healthy brain

The central issue of the dissertation is to investigate the neural-cognitive basis of writing and copying figures focusing on fine motor abilities. The neuronal recycling hypothesis is used as the theoretical framework, assuming that the ability to use pen emerged from other closely related cognitive abilities. The thesis contained four independent studies with either ischemic stroke patients or healthy participants. Chapter 2 describe the general methods used in our study. Chapter 3 is a neuropsychological study that utilizes principle component analysis and voxel-based morphometry. It explores the neural-cognitive basis underlying complex figure copying (CFC). It demonstrates the involvement of different processing stages that supports figure copying along the dorsal pathway, from visual through eye-hand coordination to the motor associative cortex. Chapters 4-6 focus on writing abilities, across two different systems: phonological and logographic. Chapter 4, is a neuropsychological study that utilized machine learning to explore the latent relationship between writing with other cognitive tasks in English and Chinese. Across the two-writing systems impairment in writing skills could be reliably classified using the same features. These cognitive features were related to CFC, attention, reading, memory and age. Chapter 5 presents two neuropsychological studies that examine the neuro-cognitive makeup of the ability to write words (phonological) and numbers (logographic). The first study is a detail comorbidity analysis of writing deficits of words, numbers, language and motor deficits. It demonstrates that pure writing deficits are very rare, with the majority of writing deficits overlapping with motor (CFC) or language impairments. The second study in this chapter is a VBM study focus on writing numbers and words. We identified two dissociable networks that have been specifically evolved to support writing: a visual-manual motor ability to use pen mediated by right angular and middle frontal gyri; and an ability to transform symbolic representations grapheme to manual programs for use with the pen. Chapter 6 is an fMRI study with healthy participants investigating the neural substrates associated with writing English, Chinese and Pinyin. The study identifies different brain networks that support writing abilities across writing systems: visual information perception and visual motor transformation, semantic component. Chapter 7, summarize and compare the main finding of the four studies. Overall, the studies demonstrate the close relations between the sue of pen and other more basic cognitive functions, such as control of hand movement, language, attention. As predicted by the neuronal recycling hypothesis there were minimal pure deficits of writing or copying; and for proficient writers, the same neural structures supported different writing systems

Comorbidities of visual spatial attention deficits in acquired brain lesion: the case of reading and working memory

Visual spatial neglect (VSN), a disordered to attentional processing, is a common neuropsychological syndrome following brain injury. Presence of VSN adversely affects recovery. The interplay of spatial and non-spatial attentional components in the syndrome has been a matter of debate. The current thesis examined the comorbidities of cognitive deficits and VSN. The working assumption is that attention ‘acts’ upon other cognitive processes, therefore the error pattern of comorbid deficits should reflect the impaired attentional components. Two cognitive comorbidities were examined: reading and working memory (WM). The relations between Reading/WM and VSN were assessed using three different methodologies: meta-analyses of the literature; analyses of two large databases of stroke patients; and experimental case studies testing the impact of saliency on spatial bias symptoms. The results suggest that patients who suffer from VSN are more likely to experience problems in reading and WM. Surprisingly, the spatial biases of VSN did not affect errors in reading or WM. Regression analyses showed non-spatial components of attention explained the comorbidity deficits better than spatial component. The experimental chapters showed that non-spatial saliency cues exasperate the spatial bias symptoms. Taken together the current thesis provide evidence supporting a non-spatial attention deficit as a core symptom of VSN