Decision making: A new distribution of tasks in our prefrontal cortex?


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Summary: The study shows how specific tasks are distributed to different areas within 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) at the Paris Brain Institute, proposes in a study published in the publication Journal of Neuroscience a new approach to understanding how our prefrontal cortex makes decisions.

Decision making: costs and benefits

A decision is based on a fine balance between costs and benefits. In other words, when faced with multiple options, we must identify the one that brings the greatest profit with the least effort. When we are faced with this situation, which almost always occurs in our lives, a series of operations take place in our brain to evaluate the different options that are presented to us and to choose the best one.

“While the role of the prefrontal cortex in assessing effort and reward is well accepted, the functional role of each sub-region is controversial as results from different studies are conflicting,” explains Nicolas Clairis, first author of the study, currently a postdoctoral student at the Ecole Polytechnique Federal de Lausanne (EPFL, Switzerland).

Consideration and trust in one’s own decisions

To answer this question, the team led by Mathias Pessiglione from the Paris Brain Institute took a different approach to clarifying the distribution of roles in the prefrontal cortex. To do this, they considered the metacognitive part of the decision, ie the costs and benefits of the consideration itself (spend time thinking to have more confidence in one’s decision).

When making a decision like “Do I want to climb further up the pass to get a view of the other valley? scree high and that seems difficult) and the reward ahead (I’ve been told that the view from up there is really nice), but also the confidence in the choice under consideration (am I right to continue?) and the Thinking time (do I need to think more about it?)

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 choices – 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 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 reward promised and decreases according to the cost of the effort required to obtain it.

Their results confirm the role of the ventromedial prefrontal cortex (vmPFC) in assigning a value to the different options presented during a choice. The image is in the public domain

The more dorsal regions of the prefrontal cortex are more associated with the metacognitive variables proposed by the Paris Brain Institute team.

Confidence in one’s decisions is reflected in medial prefrontal cortex (mPFC) activity, while thinking time is actively reflected in the dorsomedial prefrontal cortex (dmPFC).

“Here we confirm the value of distinguishing between variables that determine decision (effort and reward) and those that determine meta-decision (when to stop making one’s choice) in understanding the functional architecture of the prefrontal cortex.

“The advantage of the new conceptual framework is that it can be easily generalized to behaviors other than decisions. For example, to make a judgement, there is also a metacognitive trade-off between trust and reasoning: you have to have confidence in your judgement, and at the same time you cannot take an infinite amount of time before stopping your judgement,” concludes Mathias Pessiglione, team leader at the Paris Brain Institute and senior author of the study.

About this news from neuroscientific research

Author: Nicolas Brad
Source: Paris Brain Institute
Contact: Nicolas Brard – Paris Brain Institute
Picture: The image is in the public domain

Original research: Closed access.
“Value, trust, consideration: a functional partition of the medial prefrontal cortex demonstrated across rating and choice tasks” by Mathias Pessiglione et al. Journal of Neuroscience

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Value, trust, consideration: A functional partition of the medial prefrontal cortex demonstrated across rating and choice tasks

Deciding on options for action is about minimizing costs and maximizing benefits. Studies in decision neuroscience have implicated both the ventral and dorsal medial prefrontal cortex (vmPFC and dmPFC) in target value and action cost signaling, but the precise functional role of these regions is still controversial.

Here we propose a more general functional division that applies not only to decisions, but also to judgments about target value (expected reward) and cost of action (expected effort). In this conceptual framework, cognitive representations related to options (reward value and effort cost) are separated from metacognitive representations (trust and deliberation) related to task completion (judgment or choice).

We used an original approach aiming to identify consistencies across multiple preference tasks, from liking ratings to binary choices involving both attribute integration and option comparison. fMRI results in human male and female participants confirmed that vmPFC is a generic scoring system whose activity increases with reward value and decreases with effort cost.

In contrast, more dorsal regions were not concerned with evaluating options but with metacognitive variables, with confidence reflected in mPFC activity and reflection time in dmPFC activity.

Thus, there was a dissociation between the effort for choices (represented in the vmPFC) and the effort for deliberation (represented in the dmPFC), the latter being expressed in pupil dilation.

More generally, assessing commonalities between preference tasks could help provide a unified view of the neural mechanisms underlying the cost-benefit trade-offs that determine human behavior.

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