Neural Mechanisms of Attention-Based Operation in Working Memory

Attention and working memory are intrinsically bound, but the neural mechanisms of their interaction are still less understood. The goal of this thesis is to establish a framework that provides neural representations for understanding the operation of attentional control in working memory with the evidence integrated from behavioural measures, event-related potentials (ERPs), and functional magnetic resonance imaging (fMRI). Chapter 3 demonstrates the two ERPs experiments that examine whether selecting relevant target items from within working memory representations involves spatially specific, retinotopic biasing of neural activity in a manner analogous to that which occurs during visual search for target items in perceptual domain. Chapter 4 describes an event-related fMRI experiment that investigates the neural correlates of the effectiveness of orienting attention during retention and the mnemonic evaluation whilst comparing working memory representations with current perceptual stimuli. Chapter 5 shows an event-related fMRI study that demonstrates that the neural activity in the posterior areas is modulated by reflectively transient attention-based operation during working memory retention. Finally, I identify the neural network of the brain regions associated with the top-down attentional operation in working memory representations using coherence analysis in Chapter 6. In conclusion, I investigate the interaction within a distributed neural network for supporting attentional operation and how the cognitive framework of attentional operation in working memory can be implemented with a dynamic neural network in the brain. Based on the findings and implications, directions for future research are discussed.