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Neural basis of rule-based decisions with graded choice biases

dc.contributor.advisorGail, Alexander Prof. Dr.
dc.contributor.authorSuriya-Arunroj, Lalitta
dc.titleNeural basis of rule-based decisions with graded choice biasesde
dc.contributor.refereeGail, Alexander Prof. Dr.
dc.description.abstractengIn every hour of every day we are faced with options; which route to take to work, where to go for a meal, which stocks to invest in. However, with limitations of movement, time and budget, our options are constrained. We are obliged to cut off (decide: from Latin dēcīdere, to cut off) and reduce the available options until we are left with a single course to pursue. Since the 1970s, the decision-making process has been described by the centralized view of a good-based model in which options are cut off within the executive brain areas in the frontal lobe (Norman & Shallice 1980; Padoa-Schioppa 2011), with the resulting choice outcome fed into sensorimotor areas in order to plan the chosen movement. More recently, an increasing body of evidence has revealed a decision-making network spanning multiple brain regions, including sensorimotor cortices which have been found to represent potential motor plans before the decision is made (Cisek 2012). Representation of potential actions has been proposed to play a crucial role in decision-making: options are first identified so that values can be assigned to each of them, then the decision-making process will weigh these options and, finally, produce a choice (Rangel et al. 2008). This emerging view regards action-based decision-making, at least for decision involving movement, as a competition between movement plans (Cisek 2007). Neural activity in the sensorimotor system has been shown to represent, before the decision is made, available options (Klaes et al. 2011; Thura & Cisek 2014; Yang & Shadlen 2007) and reward expectation (Sugrue et al. 2004; Platt & Glimcher 1999). Furthermore, perturbation of the sensorimotor systems, via micro-stimulation or inactivation of the neural population representing one of the potential action plans, has been shown to bias choice probability (McPeek & Keller 2004; Carello & Krauzlis 2004; Schieber 2000; Oliveira et al. 2010; Cisek 2012). However, to our knowledge, no study has so far shown that the effect of imbalanced planning alone, without reward contrast between options, could also induce selection bias. This thesis deals with the influence of planning on decision-making and comprises two main experiments, upon which the structure of this thesis will be organized. First, a psychophysical experiment was conducted with human participants, in which behavioral responses were collected and analyzed to provide first insights into how the decision-making process deals with different task manipulations. The second electrophysiological experiment in monkeys allowed us to record activities at the level of single neurons while rhesus monkeys (macaca mulatta) solved choice tasks, yielding data with high temporal and spatial resolution. As the behavioral task involved reach movements, our sensorimotor areas of interest were the dorsal premotor cortex (PMd) and the parietal reach region (PRR), which are known to form the frontoparietal network of reach planning. The first chapter will start with brief literature reviews of the different perspectives on decision-making mechanisms in the brain, then it will introduce the current state of knowledge of sensorimotor transformations in the frontoparietal network, followed by an overview of known properties of neurons in the areas of interest. It will introduce some terminology and experimental paradigms frequently employed in the field, and will end with the summarized aim of this PhD project. The second chapter will describe and discuss the psychophysical experiment, entitled “I plan therefore I choose: Free-choice bias due to prior action-probability but not action-value”. The third chapter will deal with the monkey physiology experiment under the title “Biased action selection due to imbalanced action preparation”. Finally, the last chapter will comprise a brief summary and general discussion of the
dc.contributor.coRefereeTreue, Stefan Prof. Dr.
dc.subject.engreach movementde
dc.subject.engmotor planningde
dc.subject.engprior probabilityde
dc.subject.engsensorimotor areasde
dc.subject.engrule-based decision-makingde
dc.subject.engaction selectionde
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de

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