Orienting towards salient environmental stimuli is necessary for the survival and well-being of most organisms. In humans, an orienting response (OR) is elicited by a novel, significant or emotional stimulus and is manifested as a complex of behavioral, neural and autonomic responses. Two subregions within the prefrontal cortex, the orbitofrontal (OFC) and the lateral (LPFC) prefrontal cortices, are involved in the executive control of orienting and subsequent attention allocation. Previous research suggests a double dissociation in the function of these two areas: While the LPFC is essential for executive control of cognition, the OFC is important for executive control of emotional and social information processing. I plan to explore the contributions of these PFC subregions to processing of both neutral novel and emotional novel stimuli that elicit an OR. By testing patients with damage to either subregion, I will characterize the selective contributions of each area to orienting and attention allocation. We will use behavioral (reaction time) as well as central and peripheral neural markers (electrophysiology and skin conductance resistance, respectively) of the orienting response. We predict that the OFC provides mainly inhibitory control over emotional novel and neutral novel information processing whereas the LPFC exerts comparable excitatory control over all forms of novelty detection.
