Mechanisms of visuomotor transformations in the primate frontal cortex

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The brain is a complex organ that received sensory signals and then produces according to the organism internal goals commands to move the muscles that execute actions. This process of sensory-to-motor transformation is complex and it has been challenging to understand the role of different brain areas in its various steps. Previous studies in monkeys have disentangled some of the basic mechanisms at the sensory and motor ends of the transformation, by identifying brain areas in which sensory and motor signals are almost exclusively encoded (e.g., sensory and motor cortices). Others have identified brain areas that contain a mix of sensory and motor signals, mainly during the execution of gaze movements (saccades) towards visual targets. Of particular interest are areas of the frontal lobe that may also play a role in learning. How are visual signals transformed into gaze commands within these areas remains poorly understood. The current proposal continues the research we have undertaken in the previous Discovery grant. We have targeted an area of the frontal cortex, the Frontal Eye Fields (FEF) as candidate for performing visuomotor transformations for gaze during complex tasks. We will test two main hypotheses. First, that visual information reaches visual neurons within the FEF, and then is transferred to visuomovement neurons that finally pass the information to movement neurons. Second, we will test the hypothesis that the FEF plays an important role in the learning of visuomotor associations. We anticipate that some FEF neurons become selective for visual cues carrying the meaning of the association and that learning occurs when these units strengthen their connectivity with movement neurons encoding the location of the intended saccadic eye movement. We will use a combination of multielectrode array recordings and behavioural measurements in awake monkeys performing visuomotor tasks. This will allow us to characterize the response and explore interactions amongst the different neuronal types within the FEF using correlation and Granger causality analyses. Our results will reveal the mechanisms of visuomotor transformation as well as the neural substrates of visuomotor learning in the primate frontal lobe.