A new study led by researchers at the Brain and Spine Institute in Paris have discovered that the brain’s memory systems help in resisting temptations.
The researchers noted that one factor that helps explain the difference in people’s ability to resist temptation lies in the activity of a deep brain structure — the hippocampus.
The conflict between a smaller reward today vs. a larger reward at a later time has been studied for decades. Understanding how humans make choices, such as drinking tonight versus good health later, is crucial for designing insurance policies or anti-alcohol campaigns, the researchers noted.
This led to one study where volunteers’ brains were scanned while they were asked to make choices between monetary payoffs, for instance $10 now versus $11 tomorrow.
Using this type of paradigm, scientists found that the dorsolateral part of the prefrontal cortex, a region known to implement behavioral control, was crucial for making the choice to delay immediate gratification and wait for higher payoffs.
“However, these paradigms miss an essential feature of the inter-temporal conflicts we have to face in everyday life,” noted study leader Mathias Pessiglione, Ph.D. “Immediate rewards can be perceived through our senses, whereas future rewards must be represented in our imagination.”
To produce this situation in the lab, the researchers used more natural rewards, for instance, a beer today or a bottle of champagne a week from now.
Volunteers were confronted with the choice between immediate rewards, presented as pictures, and future rewards, which were presented as text.
The researchers found in this experiment that the ability to select future rewards was linked to the amount of activity in the hippocampus.
To complete the experiment, individuals with hippocampus damage due to Alzheimer’s disease were tested in the same task, as were individuals with a behavioral variant of frontotemporal dementia (bvFTD), arising from prefrontal degeneration.
The researchers found that individuals with bvFTD exhibited excessive impulsivity in all sorts of choices, while those with Alzheimer’s were specifically biased towards immediate rewards when future rewards had to be imagined.
“This is because the hippocampus is necessary for imagining future situations with a richness of details that make them attractive enough,” said Pessiglione.
“Indeed, this structure has long been considered as essential for storing past episodes, but scientists have recently discovered that it is also involved in simulating future situations. The consequence is that patients with hippocampus damage suffer not only from memory deficits, but also from a difficulty in imagining goals that would counter the attraction of immediate rewards and motivate their actions on the long run.”
Source: Public Library of Science