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In a post-hoc analysis of fMRI data from a 2-party bargaining game we found that the effective connectivity between three regions of interest - the right temperoparietal junction (rTPJ), the right dorsolateral prefrontal cortex (DLPFC) and left Brodmann area 10 (BA10) - was significantly modulated by strategic sophistication. In particular effective connectivity to and from the rTPJ showed a reversal when considering the most strategically sophisticated, vs. the least strategically sophisticated types, with information generally flowing from the rTPJ to the frontal regions in the sophisticated "strategists", and flowing from these frontal regions to rTPJ in the na?ve "incrementalists". The effective connectivity from the rTPJ to both frontal regions in this context highlights the importance of stimulus driven attention for strategic sophistication in this task. Conversely, the na?ve players tend to exhibit more rule-driven behavior, as reflected by the more top-down nature of their effective circuit. In order to assess the effective connectivity among these areas we utilized a novel adaptation of Granger causality that accounts for signal-dependent noise. We found that due to the prevalence of signal-dependent noise in fMRI data, this adaptation is critical, giving very different results than those found using classical Granger causality. |
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Keywords:Mathematical biology, Social Strategy, Signal-dependent noise, Time-varying Granger causality, Neuroeconomics |
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