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dc.contributor.authorThevarajah, Dhushan
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date2009-01-30 17:11:21.002en
dc.date.accessioned2009-02-02T19:50:40Z
dc.date.available2009-02-02T19:50:40Z
dc.date.issued2009-02-02T19:50:40Z
dc.identifier.urihttp://hdl.handle.net/1974/1690
dc.descriptionThesis (Master, Neuroscience Studies) -- Queen's University, 2009-01-30 17:11:21.002en
dc.description.abstractGame theory outlines optimal response strategies during mixed-strategy competitions in which available actions are selected probabilistically. The neural processes involved in choosing individual strategic actions, however, remain poorly understood. Here, actions need to be selected (1) in the absence of sensory instruction or reward cues and (2) independent of previous events. This thesis examines the neural processes involved in action selection during mixed-strategy competition. To do so, we both measured and manipulated presaccadic activity in the primate superior colliculus (SC), a structure involved in the generation of orienting saccadic eye movements, during a strategic game. The first study tested whether the SC is involved in choosing saccades under strategic conditions. Monkeys were free to choose either of two saccade targets as they competed against a computer opponent during the mixed-strategy game ‘matching-pennies’. The accuracy with which pre-saccadic SC activity predicted upcoming choice gradually increased in the time leading up to the saccade. Probing the SC with supra-threshold stimulation demonstrated that these evolving signals were functionally involved in preparing strategic saccades. Finally, sub-threshold stimulation of the SC increased the likelihood that contralateral saccades were selected. In the second study, we compared the influence of previous actions and rewards on updating premotor activity in the SC in the strategic condition where eliciting stochastic responses was optimal and in a non-strategic condition where stochastic responses were also elicited but through explicit instruction. To avoid exploitation by opponents during mixed-strategy competitions one should select behaviors unpredictably, that is, independent of previous choices and their outcomes. The iterative updating of neural processes involved in selecting actions to produce mixed-strategy behaviors, however, remain poorly understood In both tasks, premotor activity and behavior were shaped by past actions and rewards with more recent events exerting the largest influence. Importantly, these sequential effects were attenuated under strategic conditions suggesting that updating of selection processes is not entirely automatic but can be tailored to different decision-making contexts. Together our results highlight the active role played by the brain in choosing strategic actions.en
dc.format.extent1238893 bytes
dc.format.mimetypeapplication/pdf
dc.languageenen
dc.language.isoenen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectdecision makingen
dc.subjectmixed-strategyen
dc.subjectsuperior colliculusen
dc.subjectmonkeyen
dc.subjectmotor intentionen
dc.subjectreinforcementen
dc.subjectsaccadeen
dc.titleNeural Processes Involved in Action Selection During a Mixed-Strategy Gameen
dc.typethesisen
dc.description.degreeMasteren
dc.contributor.supervisorDorris, Michael C.en
dc.contributor.departmentNeuroscience Studiesen


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