CORTEX conference by Emiliano Macaluso

Fronto-parietal regions are traditionally associated with the control of visuo-spatial attention. Extensive investigation showed that both stimulus- and task-related factors can modulate the activity of these areas. Nonetheless, the vast majority of the previous studies made use of stereotyped paradigms (e.g. using repeated presentations of simple geometrical shapes) that emphasise aspects of attention control that may be specific to such artificial situations, while missing other types of signals that are relevant for orienting in natural, everyday-life situations. Here I will present a series of studies where we investigated the role of (external) stimulus-related and (internal) knowledge-related signals for overt spatial orienting in complex and dynamic situations. We employed short video-clips depicting natural scenes and virtual environments involving active exploratory behavior. We characterized the sensory input associated with these complex stimuli by computing saliency maps ("external" signals) and by categorizing distinctive objects/events as a function of their "internal" relevance (task, semantics, memory). Using functional neuroimaging we asked how these different types of signals affect the activity of fronto-parietal areas. We sought to further corroborate our findings by examining orienting behavior in neglect patients with lesioned ventral regions. Overall our results link the processing of "internal" knowledge-related signals with ventral fronto-parietal areas, while dorsal regions appear to engage primarily when "external" sensory signals guide spatial orienting. Albeit still in its early days, experimentation with complex and dynamic material provides us with a tool to bridge the gap between results obtained in the laboratory and the understanding of brain functions - and dysfunctions - in real world conditions.