Hemispheric Asymmetries in Visuospatial Attention: Functional Dissociations and Modulation of Visual Processing

Visuospatial attention is one of the most studied psychological constructs. It represents a central mechanism for regulating human cognition, facilitating the selection and integration of stimuli from the surrounding world. To date, the study of visuospatial attention has relied on traditional methods such as behavioral data and techniques based on measuring brain function, including neuroimaging and neurostimulation. Recently, a growing body of literature has focused on how specific procedures can enhance cognitive and attentional performance, while also investigating the neural bases underlying these effects. After providing a theoretical overview that defines the framework for studies on visuospatial attention (Chapter 1), we reviewed the current methodologies for investigating thisconstruct throug a systematic approach (Chapter 2), with particular emphasis on the integration of Non-invasive Brain Stimulation (NIBS) with multimodal neuroimaging, highlighting both the strengths and limitations of the current state of the art. Building on this foundation, we investigated the neural mechanisms of plasticity induced by prolonged spatial attentional imbalance, and examined how this imbalance - combined with NIBS - can be used to clarify the respective roles of the right and left hemispheres in supporting visuospatial attention (Chapter 3). In particular, attentional imbalance and the resulting enhancement in visual attention performance appear to be induced and modulated by plasticity-dependent mechanisms, which are central to the theoretical framework of interhemispheric competition. Finally, the neural and electrophysiological bases underlying attentional imbalance and the associated enhancement in visual attention performance were preliminary investigated using electroencephalography (EEG) (Chapter 4). The thesis concludes with final remarks and future directions (Chapter 5) .