Summary: The study reveals how specific tasks are distributed in different areas of the prefrontal cortex to facilitate decision-making processes.
Source: Paris Brain Institute
The “Motivation, Brain and Behavior” team, co-directed by Mathias Pessiglione (Inserm) at the Paris Brain Institute, proposes 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
Decision-making is based on a fair balance between costs and benefits. In other words, faced with several options, we must identify the one that will offer the greatest reward with the least effort. When we are faced with this situation, which happens almost all the time in our life, a series of operations take place in our brain to evaluate the different possibilities available to us and choose the best one.
“While the role of the prefrontal cortex in the evaluation of effort and reward is well accepted, the functional role of each sub-region is subject to debate, because the results obtained in different studies are contradictory”, explains Nicolas Clairis , first author of the study, currently a post-doctoral fellow at the Ecole Polytechnique Fédérale de Lausanne (EPFL, Switzerland).
Deliberation and confidence in one’s own choices
To try to answer this question, the team of Mathias Pessiglione at the Paris Brain Institute adopted another approach, in order to clarify the distribution of roles in the prefrontal cortex. To do this, they took into account the metacognitive part of the decision, that is to say the costs and benefits of the deliberation itself (spending time thinking to have more confidence in one’s decision).
Thus, in a decision of the type “Do I continue to the pass to have the view of the other valley?” », it is necessary to evaluate not only the option envisaged, that is to say the effort to be provided (you have to climb all the top of the scree and it seems difficult) and the reward to come (I am said the view is really nice from up there), but also the confidence in the choice being considered (am I right to want to continue?) and the time for deliberation (do I need to think about it more?)
The researchers presented 39 participants with several preference tasks ranging from ratings: do you like this option a little, a lot or not at all? – as well as binary decisions – do you prefer option A or B? Are you ready to put in so much effort for so many rewards? These tests were combined with functional imaging (fMRI).
A new distribution of tasks 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 according to the value of the promised reward and decreases according to the cost of the effort necessary to obtain it.
The more dorsal regions of the prefrontal cortex are more associated with the metacognitive variables proposed by the team from the Institut du Cerveau de Paris.
Confidence in one’s own choices is represented in the activity of the medial prefrontal cortex (mPFC), while deliberation time is reflected active in the dorsomedial prefrontal cortex (dmPFC).
“We confirm here the interest of distinguishing the variables which determine the decision (effort and reward) from those which determine the meta-decision (when to make a choice) to understand the functional architecture of the prefrontal cortex.
“The advantage of the new conceptual framework is that it can easily be generalized to other types of behavior than choices. For example, to make a judgement, there is also a metacognitive trade-off between trust and deliberation: you have to have confidence in your judgment, and at the same time you can’t take an infinite amount of time before making your judgment”, concludes Mathias Pessiglione, team leader at the Paris Brain Institute and last author of the study.
About this neuroscience research news
Author: Nicolas Brard
Source: Paris Brain Institute
Contact: Nicolas Brard – Paris Brain Institute
Image: Image is in public domain
Original research: Access closed.
“Value, trust, deliberation: a functional partition of the medial prefrontal cortex demonstrated in evaluation and choice tasks” by Mathias Pessiglione et al. Journal of Neuroscience
Value, trust, deliberation: a functional partition of the medial prefrontal cortex demonstrated in evaluation and choice tasks
Deciding on courses of action involves minimizing costs and maximizing benefits. Studies in decisional neuroscience have implicated both the ventral and dorsal medial prefrontal cortices (vmPFCs and dmPFCs) in signaling goal value and action cost, but the precise functional role of these regions is still unclear. a subject of debate.
Here we suggest a more general functional partition that applies not only to decisions but also to judgments about the value of the goal (expected reward) and the cost of action (expected effort). In this conceptual framework, cognitive representations related to options (value of the reward and cost of effort) are dissociated from metacognitive representations (trust and deliberation) related to the resolution of the task (making a judgment or making a choice).
We used an original approach aimed at identifying the coherences between several preference tasks, from liking ratings to binary decisions involving both the integration of attributes and the comparison of options. The fMRI results in human male and female participants confirmed that the vmPFC was 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 option appraisal but with metacognitive variables, with trust reflected in mPFC activity and deliberation time in dmPFC activity.
Thus, there is a dissociation between the effort attached to the choice options (represented in the vmPFC) and the effort invested in deliberation (represented in the dmPFC), the latter being expressed in pupil dilation.
More generally, assessing commonalities between preference tasks could help achieve a unified view of the neural mechanisms underlying the cost/benefit trade-offs that govern human behavior.