Date of Graduation

5-2014

Document Type

Thesis

Degree Name

Bachelor of Science

Degree Level

Undergraduate

Department

Physics

Advisor

Shew, Woodrow

Reader

Oliver, William

Second Reader

Hare, Laurence

Third Reader

Wu, Jingxian

Abstract

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this paper is on the role of criticality in visual sensory information processing. One line of previous work suggests that the dynamic range of the network, when presented with outside stimulus, is maximized at criticality. Another line of previous work suggests that adaptation to changes in visual input serves to improve dynamic range. A third line of work suggests that adaptation can bring about criticality. Taken together, these three previous ideas suggest that adaptation to visual input will bring about criticality. Thus, our hypothesis was that visually driven activity does operate near criticality, except during a transient period of adaptation immediately after the onset of the stimulus. We experimentally confirmed this hypothesis; we demonstrate that sensory driven cortex dynamics maintain signatures of criticality and in good agreement with our model; the transient response to the stimulus onset is not critical, but supercritical.

Share

COinS