The drift diffusion model (DDM) (Ratcliff

1978; Ratcliff

The drift diffusion model (DDM) (Ratcliff

1978; selleck inhibitor Ratcliff and Smith 2004) of perceptual decision-making has gained in popularity because of its ability to explain observed trade-offs between speed and accuracy. Unlike SDT that suggests a single decision-criterion, DDM suggest two criteria—one for each alternative. These criteria are represented in terms of decision boundaries which, when bias is neutral, lie an equal distance but on opposite sides of a point at which evidence accumulation begins. Inhibitors,research,lifescience,medical Here, response bias is modeled as a shift in the starting point toward one decision boundary and away from the other. Perceptual decision-making studies that have used DDM have found that “drift rate,” how fast accumulated evidence approaches one of the decision boundaries, is what seems to be driving the activation in the left SFS (Heekeren et al. 2006; Summerfield et al. 2006; Philiastides et al. 2011). However, Mulder and colleagues (Mulder et al. 2012), using the DDM, found that when they separately Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical manipulated prior probability and payoff matrix in a random dot-motion task, change in bias was associated with increased left IFG activation. In effect, bias toward one decision boundary or another was associated with left IFG activation. This suggests that the relationship between the change in bias and the left IFG activation is

not unique to the SDT model of decision-making. Inhibitors,research,lifescience,medical The finding that there is an association between a change in the decision criterion in both detection and discrimination studies and that this relationship transcends the model used to investigate it provides converging evidence that the left IFG is involved in adjusting decision criterion between different environments. Conclusions Flexibility in the way we make decisions allows us to maintain an optimal choice strategy as the decision environment changes.

Findings from this study suggest that the left IFG contributes to this flexibility through its involvement in adjusting how we bias our choices. Given that subsequent behavior Inhibitors,research,lifescience,medical often follows from present decisions, the left IFG may, to some extent, play a role in flexible behavior. Acknowledgments The authors would like to thank Anne Hilde Farstad for her assistance with the data collection. Conflict of interest None declared.
Despite strong evidence available to support at least 6-month use of antidepressant through to prevent relapse and recurrence, non-adherence or early discontinuation of antidepressants remained as a major treatment obstacle. A comprehensive review of papers published between 1975 and 2001 had previously reported that the early discontinuation rate was generally high, in which approximately 30% of patients stopped taking antidepressants within 1 month of commencing treatment and 45–60% stopped the prescribed treatment by 3 months (Lingam and Scott 2002).

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