Closing the loop: towards contemporary assessment and modulation of visual attention

Stroke-induced attention deficits have a large impact on activities of daily living as well as on the recovery from post-stroke disorders in the motor domain and other cognitive domains. An overarching approach that involves 1) a reliable, inclusive, and accessible assessment of attention, 2) a deep understanding of its neural mechanisms, and 3) a therapeutic intervention tailored to the individual is pivotal for the advancement of neuropsychological rehabilitation of attention deficits. The central aim of my doctoral research project is to examine and develop novel methods to assess and modulate visual attention. 

First, conventional cognitive neuropsychological assessment of visual attention has remained relatively stagnant in the past decades and tend to be lacking in reliability and sensitivity to characterise subtle deficits in visual attention. We integrated new technological developments and findings from experimental psychology to develop accessible and inclusive computerised assessments that deliver sensitive measures of visual attention (Chapters 2 and 3). Second, the intraparietal sulcus (IPS) plays a critical role in the control of attention at specific locations in the visual field, and typically shows a disrupted functionality in stroke patients with attention deficits. To further examine its properties, we related the IPS activity of neurologically healthy individuals to the allocation of attention to locations in the visual field with varying levels of eccentricity (Chapter 4). Third, we examined a novel technique named real-time functional magnetic resonance imaging (fMRI) neurofeedback, a non-invasive method that can train participants to gain control over their own brain activity. We first performed a systematic review of the literature, which showed that real-time fMRI neurofeedback allows for individualized training to improve task performance and stroke recovery (Chapter 5). Next, we constructed a real-time fMRI neurofeedback pipeline aimed at modulating visual attention, and used it to train participants to self-modulate their brain activity in the left and right IPS (Chapter 6). 

In sum, this dissertation presents the design of an accessible assessment of visual attention, an investigation of the neural mechanisms behind the allocation of attention, and the construction of a real-time fMRI neurofeedback-based training procedure built on these concepts to modulate visual attention. These new insights may offer important implications for how we approach rehabilitation of cognitive disorders following stroke in a holistic way encompassing the three pillars of rehabilitation: assessment, neural mechanisms, and therapeutic interventions.