Overview: Research reveals how specific tasks are distributed among different areas in the prefrontal cortex to aid in decision-making processes.
Source: Paris Brain Institute
The “Motivation, Brain and Behavior” team, co-led by Mathias Pessiglione (Inserm) of the Paris Brain Institute, states in a study published in the Journal of Neuroscience a new approach to understanding how our prefrontal cortex makes decisions.
Decision-making: costs and benefits
Making a decision is based on a good balance between costs and benefits. In other words, when faced with several options, we must identify the one that brings the greatest reward with the least effort. When we are faced with this situation, which is almost always in our lives, a series of operations take place in our brains to evaluate the different possibilities presented to us and choose the best one.
“If the role of the prefrontal cortex in the evaluation of effort and reward is well accepted, the functional role of each subregion is a matter of debate, as the results obtained in several studies are contradictory,” explains Nicolas Clairis, lead author of the study, currently a postdoctoral researcher at the Ecole Polytechnique Fédéral de Lausanne (EPFL, Switzerland).
Deliberation and confidence in one’s own choices
In an effort to answer this question, Mathias Pessiglione’s team at the Paris Brain Institute took a different approach to clarify the role distribution in the prefrontal cortex. In doing so, they took into account the metacognitive part of the decision, namely the costs and benefits of the deliberation itself (spending time thinking to have more confidence in your decision).
So when making a decision like “Do I continue to the pass to get the view of the other valley?”, one should not only evaluate the option considered, ie the effort to be made (you have to go all the way up the slope and that seems difficult) and the reward to come (I’ve heard the view from there is very nice), but also the confidence in the choice being considered (am I right in wanting to continue?) and the time of deliberation ( should I think about it more?)
The researchers presented 39 participants with different preference tasks that ranged from assessments – do you like this option a little, a lot, or not at all? – besides binary decisions – do you prefer option A or B? Are you willing to put in so much effort for so much reward? These tests were combined with functional imaging (fMRI).
A new division of labor in our prefrontal cortex
Their results confirm the role of the ventromedial prefrontal cortex (vmPFC) in assigning a value to the different options presented during a choice. Thus, the activity of this region increases with the value of the promised reward and decreases with the cost of the effort required to obtain it.
The more dorsal regions of the prefrontal cortex are more associated with the metacognitive variables proposed by the team at the Paris Brain Institute.
Confidence in one’s own choices is reflected in the activity of the medial prefrontal cortex (mPFC), while deliberation time is actively reflected in the dorsomedial prefrontal cortex (dmPFC).
“Here we affirm the value of distinguishing between variables that determine decision (effort and reward) and those that determine meta-decision (when choice is discontinued) in understanding the functional architecture of the prefrontal cortex.
“The advantage of the new conceptual framework is that it can easily be generalized to behaviors other than choices. For example, to make a judgment, there is also a metacognitive trade-off between trust and deliberation: you have to have faith in your judgment, and at the same time you cannot take an infinite amount of time before you stop your judgment,” concludes Mathias Pessiglione, team leader at the Paris Brain Institute and final author of the study.
About this neuroscience research news
Original research: Closed access.
†Value, trust, deliberation: a functional partition of the medial prefrontal cortex demonstrated in assessment and choice tasksby Mathias Pessiglione et al. Journal of Neuroscience
Value, trust, deliberation: a functional partition of the medial prefrontal cortex demonstrated in assessment and choice tasks
Deciding on actions involves minimizing costs and maximizing benefits. Decision neuroscience studies have implicated both the ventral and dorsal medial prefrontal cortex (vmPFC and dmPFC) in target value signaling and action costs, but the precise functional role of these regions is still a matter of debate.
Here we propose a more general functional distribution that applies not only to decisions, but also to judgments about target value (expected reward) and action costs (expected effort). In this conceptual framework, cognitive representations related to options (reward value and effort costs) are disconnected from metacognitive representations (trust and consultation) related to task solving (making a judgment or making a choice).
We used an original approach that aimed to identify consistencies in various preference tasks, from sympathy assessments to binary decisions involving both attribute integration and option comparison. fMRI results in human male and female participants confirmed the vmPFC as a generic rating system, with its activity increasing with reward value and decreasing with effort cost.
In contrast, more dorsal regions were not concerned with options valuation, but with metacognitive variables, reflecting confidence in mPFC activity and deliberation time in dmPFC activity.
Thus, there was a dissociation between the effort for choice (represented in the vmPFC) and the effort invested in deliberation (represented in the dmPFC), the latter being expressed in pupil dilation.
More broadly, assessing similarities between preferred tasks can help provide a unified view of the neural mechanisms underlying the cost-benefit tradeoffs that drive human behavior.