Cortical Contributions to Smooth Pursuit Learning
- Author(s): Li, Jennifer Xinge
- Advisor(s): Lisberger, Stephen G
- et al.
For a learned movement to be effective, it must be produced at the appropriate time, but how this is achieved in the brain remains unknown. Smooth pursuit is a simple oculomotor behavior that exhibits temporally specific learning. Upon repeated exposure to a precisely-timed instructive change in target direction, the pursuit system learns to produce an eye movement that peaks around time when the instructive stimulus is expected to appear. The smooth eye movement region of the frontal eye fields (FEFSEM), a motor cortex for smooth pursuit, contains a spatial map of elapsed time since the initiation of pursuit, and is therefore a good candidate for mediating the temporal specificity of pursuit learning. In chapter 1, I describe a series of electrophysiology experiments demonstrating that the FEFSEM, by virtue of its innate representation of time, may serve to incorporate the salient temporal features of the instructive stimulus into the learned eye movement.
Because movements improve and become ingrained with practice, motor learning is inherently a dynamic process. In chapter 2, I explored the neural changes associated with the dynamics of motor learning by comparing how activity in the FEFSEM and a downstream cerebellar locus for pursuit, the floccular complex, emerged and evolved as the animal learned to produce the desired eye movement. My findings suggest that pursuit learning arises from a combination of neural processes with different dynamics of adaptation, and that the FEFSEM and the floccular complex utilize these processes in different ways to support at least partially separate aspects of pursuit learning.