Everyday life is pervaded by prospects presenting risks and potential rewards, and the ability to decide effectively is critical for survival. Existing literature implicates integrated action of multiple neocortical and subcortical areas, yet the mechanisms underlying risky decision-making remain debated. Here, the processing of elementary prospects, bearing variable potential losses, gains and associated outcome probabilities was investigated through multiple modalities. Autonomic monitoring indicated very limited involvement of peripheral arousal in economic parameter representation, qualifying the somatic marker hypothesis. Electroencephalography demonstrated marked dissociation between long- latency cortical potentials, tracking potential gains and value, and alpha-band arousal response to potential losses and amount magnitude. Univariate functional MRI revealed a differential cortical representation of potential losses and gains, action of the mesial prefrontal cortex as decisional comparator and involvement of the insula in encoding outcome uncertainty. Subsequent graph-based network analysis demonstrated that the medial and anterior lateral prefrontal cortices harbour key value-integrating hubs, characterized by large numbers of effective connections and high topological centrality. Predicated on the apparent lack of striatal involvement indicated by functional MRI, a behavioural experiment was conducted on patients with basal ganglia degeneration, confirming normal decisional performance. Exploring the role of the lateral prefrontal cortex in regulating risk propensity and representation of gains and losses, a direct-current neuromodulation experiment was performed: though no changes in decisional pattern were observed, enhancing right hemisphere activity boosted confidence, echoing the biases observed in pathological gamblers. These results highlight that value determination proceeds through a distributed neocortical representation of specific economic parameters, particularly losses, feeding into densely-interconnected integrative hubs in the mesial and anterior lateral prefrontal cortex. Future work will need to confirm the effect of real vs. virtual financial endowment, explore the generalization to prospects presenting different combinations of options and investigate relevant patient populations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:589949 |
| Date | January 2012 |
| Creators | Minati, Ludovico |
| Publisher | University of Brighton |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://research.brighton.ac.uk/en/studentTheses/7a8e582a-4a20-4eed-8640-16b77584e697 |
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