Author ORCID Identifier
Date of Graduation
Doctor of Philosophy (PhD)
John H. Byrne
Patterns of neural activity in the brain constantly shift between different processing states. Earlier studies have established that the ongoing, spontaneous activity has major repercussions regarding how the brain processes incoming sensory stimuli. However, the interaction between behavioral activity and brain states throughout the cortical hierarchy of primates has not been understood. In particular, technical considerations have greatly limited the range of physical activities in which primate neuronal activity can be recorded. We have implemented two separate strategies to overcome these limitations. First, we have advanced wireless electrophysiological methodologies that enable recording high-yield neuronal data from animals as they freely move around an experimental arena. Using this approach, we found that activity in the dorsolateral prefrontal cortex is desynchronized during locomotion and that this desynchronization is associated with increased arousal, as indicated by pupil diameter. Second, we developed a system to record neuronal activity during locomotion in head-fixed animals, which enables precise interrogation of changes in visual processing during locomotion. We found that locomotion desynchronizes cortical state in area V4, a mid-level visual region, and that visual encoding of color is enhanced during locomotion. Finally, we recorded visual responses in a rapid adaptation paradigm and found that, while adaptation generally reduces correlations and improves stimulus encoding by the population, these effects are either greatly reduced or abolished during locomotion. Overall, these results indicate that locomotion-associated changes in cortical state are an important feature across primate cortical areas, and that they substantially impact coding of sensory stimuli. Furthermore, our efforts in developing experimental techniques provide a roadmap to guide future discoveries regarding the nature and implication of cortical states in the behaving primate.
cortical state, prefrontal, visual, synchrony, neuronal populations, freely-moving, arousal, systems, cortex