First, we developed a theoretical model, FORTIOR, describing the cortical processes leading to two well documented behavioral phenomena related to attention: facilitation and inhibition of return (IOR). Facilitation refers to the accelerated response to a visual stimulus when it is preceded by a stimulus appearing at the same peripheral location, relative to when it is preceded by a stimulus appearing at a different location. IOR is an opposite phenomena, whereby the same set of two stimuli appearing one after the other at the same peripheral location but with a longer delay between them, elicits a slower response compared to when they appear at different locations. The model is based on known facts about the anatomical and functional organization of fronto-parietal attention networks, and accounts for a broad range of behavioral findings in healthy participants and brain-damaged patients. FORTIOR does that by combining four principles of asymmetry: FORTIOR accounts for spatial asymmetries in the occurrence of IOR after brain damage and after non-invasive transcranial magnetic stimulation on parietal and frontal regions. It also provides a framework to understand dissociations between manual and saccadic IOR, and makes testable predictions for future experiments to assess its validity.
Additionally, high resolution brain activity was collected from 27 epileptic patients implanted with depth electrodes while they performed the Posner cueing task, testing their exogenous attention. The data obtained was used to test some of FORTIOR predictions, and to map the spatiotemporal dynamics of the responses across the brain to exogenous cues and targets. This studies were presented in seven international conferences and seminars, and resulted in three publications in international peer reviewed journals.
