Dynamics of Spatial Game Theory Networks with Novel Modifications

Introduction: Advances in biotechnology have shed light on many biological processes. In biological networks, nodes are used to represent the function of individual entities within a system and have historically been studied in isolation. Network structure adds edges that enable communication between nodes. An emerging fieldis to combine node function and network structure to yield network function. One of the most complex networks known in biology is the neural network within the brain. Modeling neural function will require an understanding of networks, dynamics, andneurophysiology. It is with this work that modeling techniques will be developed to work at this complex intersection. Methods: Spatial game theory was developed by Nowak in the context of modeling evolutionary dynamics, or the way in which species evolve over time. Spatial game theory offers a two dimensional view of analyzingthe state of neighbors and updating based on the surroundings. Our work builds upon this foundation by studying evolutionary game theory networks with respect to neural networks. This novel concept is that neurons may adopt a particular strategy that will allow propagation of information. The strategy may therefore act as the mechanism for gating. Furthermore, the strategy of a neuron, as in a real brain, isimpacted by the strategy of its neighbors. The techniques of spatial game theory already established by Nowak are repeated to explain two basic cases and validate the implementation of code. Two novel modifications are introduced in Chapters 3 and 4 that build on this network and may reflect neural networks. Results: The introduction of two novel modifications, mutation and rewiring, in large parametricstudies resulted in dynamics that had an intermediate amount of nodes firing at any given time. Further, even small mutation rates result in different dynamics more representative of the ideal state hypothesized. Conclusions: In both modificationsto Nowak's model, the results demonstrate the network does not become locked into a particular global state of passing all information or blocking all information. It is hypothesized that normal brain function occurs within this intermediate range and that a number of diseases are the result of moving outside of this range.

Investigating the Role of System Justification in Mental Illness Stigma

The current study integrates system justification theory with research on mental illness stigma. Stereotypes of both low- and high-status groups in society can be a means of satisfying the system justification motive, or the motive to view societal inequalities as justified (as reviewed in Jost, Banaji, & Nosek, 2004). Corrigan, Watson, and Ottati (2003) proposed that system justification theory may be able to explain the origins of particular stereotypes of people with mental illness, such as dangerousness and incompetence. The primary goal of the present study was to investigate whether the stigmatization of people with mental illness – a specific form of stigmatization of a lowstatus group – can be at least partially attributed to a broader motive to justify societal inequalities. To test this, the current study included both an experimental manipulation of the perceived legitimacy of the social system and a measure of system-justifying beliefs. Stigmatization of individuals with mental illness was measured with both explicit selfreport measures (semantic differentials and the Attribution Questionnaire) and an implicit measure (a computer-based Implicit Association Test). The relationships between participant characteristics, such as personal experience with mental illness, and stigma were also investigated. Consistent with past research demonstrating only modest correlations between explicit and implicit stigma, greater self-reported fear toward a person with a chronic mental illness was weakly associated with increased implicit bias against mental illness in favor of physical disability. There was little support for the involvement of system justification in explicit stigma. Participants with personal experience with mental illness were less likely to self-report fear and avoidance of a person with a chronic mental illness. These findings have implications for stigmareduction efforts.