UCSF

All ethologically-relevant behavior is dynamic, and biological in origin. To understand the neural underpinnings of motor behavior is then to quantify the limitations placed on organisms as they move through and interact with their environment. This thesis stands as an attempt to understand the way the brain processes information to prepare for movement, and how a network of neurons might give rise to that movement. I chose to investigate oculomotor tracking in non-human primates as a model behavior that allowed excellent spatial and temporal control over the stimulus. First, by carefully controlling the motion of a single target, and measuring the eyes' response to particular perturbations, I mapped out effective constraints on the way the brain processes target motion to guide smooth eye movements. The next set of experiments was motivated by the observation that no two tracking movements are alike, even when faced with identical stimuli. I establish the dynamic relationship between fluctuations in single neurons recorded in the frontal eye fields and concomitant behavioral fluctuations. Utilizing measurements of the covariation between simultaneously recorded neurons, I describe the properties of the network of cells which give rise said fluctuations, which is likely dominated by fluctuations in a small subset of the active population at any moment in time. Taken together, the work I've done first establishes that proper oculomotor tracking likely takes the form of a re-allocation of cortical resources, but one that may be dominated by the activity of a small number of cortical neurons.