The reason why making healthy choices feels hard is because it is literally hard work. Scientists are finding that different systems within our brains fiercely compete to assign different values to the choices we make.
In a recent study led by Cendri Hutcherson of Caltech, researchers saw this competition at play when choosing which snack to purchase. They scanned participants who had not eaten for four hours in the fMRI and asked them how much they would be willing pay for different snacks (e.g. chips, candy, etc.). The researchers asked them to make their choices while either attempting to suppress their desires to eat the food, to increase their desires to eat the food, or while acting normally. The participants then could place real bids to buy the snacks they chose.
The team found that two different brain areas competed in the selection process. When the subjects were trying to resist the food, the dorsolateral prefrontal cortex (dlPFC) was activated, whereas when they decided to eat the food, the ventromedial prefrontal cortex (vmPFC) took control.
Antonio Rangel of Caltech, CNS member and senior author on the paper, which appeared online September 26 in the Journal of Neuroscience, says that they were surprised to find the competing brain areas at work. While it is too soon to apply these findings to our everyday lives, Rangel’s lab continues to explore how the brain assigns values to everyday choices, and he shared some of his perspectives on the issue with CNS.
CNS: Why do you study the neural mechanisms of food choice?
Rangel: The lab is interested in what are the computations made by the brain to carry out different types of choices, and in how these computations are implemented and constrained by the underlying neurobiology. Most of the work that we do involves very simple choices, such as the choice between an apple or an orange for a snack. But we are also interested on how these computations change in more complex choice situations, such as those involving self-control challenges. We use food choice paradigms because they provide a very tractable choice paradigm to study these questions that also have important direct applications.
CNS: What distinguishes your recent study on the topic from past studies on food choice? How does this work fit into the broader field of neuroeconomics?
Rangel: There is a consensus in the field that the brain makes simple choices by assigning values to the options under consideration and them comparing them to make a choice. There is a big open debate, however, about whether there is a single valuation system, or competing valuation systems, that place different weights on different aspects of the stimuli (e.g., short-sighted versus long-sighted).
This paper is important for several reasons:
1. It demonstrates that there exist multiple valuations systems with different properties.
2. It shows that deliberative self-regulation can can be used to switch control among the different systems.
3. It shows that this switch of control takes time and effort, and thus might not be at work when choices are made fast.
CNS: Were you surprised by any of the findings (e.g. the dueling regions of the brain)?
Rangel: Yes. Based on previous work by our lab and others, we thought that there was a good chance that self-regulation would work simply by modulating the value signals in ventromedial prefrontal cortex, and not by activating a competing valuation system.
CNS: What are the implications of the study for the average person? Is it too soon for the current body of research to offer any advice to those of us trying to make healthy choices?
Rangel: Too soon to tell.
CNS: What are you working on next?
Rangel: Probing in more detail the neurocomputational basis of how the brain makes simple and complex choices, with a particular emphasis on understanding the exact computations carried out by different parts of the network, and the relative timing and influence of those computations.
“Cognitive Regulation during Decision Making Shifts Behavioral Control between Ventromedial and Dorsolateral Prefrontal Value Systems,” Cendri A. Hutcherson, Hilke Plassmann, James J. Gross, and Antonio Rangel, Journal of Neuroscience, online September 26, 2012.
Media contact: Lisa M.P. Munoz, CNS Public Information Officer, firstname.lastname@example.org