Cortical network dynamics during visually-guided motor behavior : Setup development and Preliminary analyses

In natural conditions, primates possess a remarkable coordination of body movements in response to highly complex sensory information from the external world. The properties of our own body and those of the objects we interact with vary over time, yet continuous online adjustments allow for movements to be combined into a smooth and efficient goal-directed behavior. A key contribution to this behavior comes from eye-hand coordination. Studying the neural underpinnings of such coordinated behaviors involves attention, visual processing, visuomotor integration, motor planning and motor control in multiple areas across the brain. This distribution has led to specialized fields in neuroscience that aim to elucidate the contribution of each respective field to visually-guided motor behavior in isolation. However, studying individual systems without taking into account their synergistic relationships diminishes our insight, as isolated behaviors in arguably independent regions of the brain are limited. The main goal of this thesis is to elucidate multi-area coordination during goal-directed behavior and provide new insights into the dynamic processes of continuous predictions and transformations from sensory to motor areas (and back). The questions on how the visual input areas and motor output areas coordinate require an experimental setup with extensive behavioral control, recording capacity of multiple effectors, and dense electrophysiological recordings in multiple relevant brain structures. In my thesis I begin by outlining aspects of visually-guided motor behavior and present classic and current ideas on how the visual input on the retina travels in parallel through a multitude of brain areas, experiencing several stages of reference frame transformation, in order to control motor output of the hand. I subsequently detail the development and testing parameters of the Real-time Integrated Visuomotor behavior & Electrophysiology Recording (RIVER) setup. This setup had to fulfill the following requirements: 1) both eye and hand positions must be expressed in the same coordinate space; 2) the setup must have real-time control over eye and hand movements within the task environment, 3) movements must be continuously tracked and recorded under any experimental condition, 4) the setup must be optimized to allow for electrophysiological recordings in human/monkey participants, and 5) the setup must have the ability to output synchronized data of behavioral and experimental events with all electrophysiological recordings. I present preliminary behavioral data from a monkey trained to perform a sequential point task in the RIVER setup, and briefly discuss the surgical procedures and outcome of multi-electrode array (MEA) implantation. Finally, I present our findings from noise correlation analysis on massively parallel electrophysiology data from a parallel reach-to-grasp project