Despite that research has shown that the prefrontal cortex (PFC) is the most important area for higher-level cognition;we remain ignorant of its functional organization. This is not surprising because unlike the primary and secondary sensory and motor areas, which process information that is more amenable to experimental control, the PFC is an """"""""association area,"""""""" where different modalities are combined, and where """"""""executive"""""""" control functions such as planning, attending, and remembering are integrated. Attuned to these challenges, we propose two aims that together embrace both functional specialization at the local level and distributed processing at the network level and will allow us to test critical hypotheses about the functional organization of the PFC. We will test the hypothesis that the dorsal lateral PFC (dIPFC) is involved in the selection of actions, and the ventral lateral PFC (vIPFC) is involved in the selection of perceptions. The hypothesis is founded on the segregated projections from the dorsal and ventral visual streams that carry visual information about actions and perceptions, respectively, to the PFC. Top-down biasing signals from PFC are hypothesized to select task relevant actions and perceptions represented in posterior cortex.
In Aim 1, we will use event-related fMRI to test the hypothesis that the dIPFC and vIPFC are involved in the selection of actions and the selection of perceptions, respectively.
In Aim 2, we will test for a double dissociation between correlated activity in the two visual streams (dorsal, ventral) and the top-down selection demands (action, perception) by functional connectivity analyses. We predict that functional coupling of activity in dorsal visual stream and dIPFC will be greater during high compared to low response selection demands. Similarly, we predict that functional coupling between the ventral visual stream and vIPFC will be greater during high compared to low visual selection demands. We expect the results of the functional connectivity analysis to identify PFC areas that are the source of the top-down control signals that bias the competition for neural representation in posterior cortical areas.
PFC control functions are thought to be compromised by a wide variety of mental health and neurological disorders including schizophrenia, autism, attention-deficit-hyperactivity-disorder (ADHD), and Parkinson's disease. An understanding of the basic neural mechanisms underlying control is a necessary first step and will lead to improved diagnostic, prognostic, and therapeutic procedures for these disorders.
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