If you had to choose between a free bag of potato chips now or a free dinner on a cruise next month, which would you choose? What about a can of beer now or a bottle of champagne in one week? When it comes to deciding whether a can of beer now is worth more than waiting for a nicer bottle of champagne later, the hippocampus — the part of the brain involved in memory — plays a role in resisting, or giving in to that temptation, a new study says.
The Hippocampus Helps Us Imagine A Future With Better Rewards
Quoting Aristotle, the researchers wrote, “When some desirable object is not actually present in our sense, exerting its pull on us directly, our motivation to strive to obtain it is driven by our awareness of its (memory or fantasy) image.” Thus, they believe that the key to resisting temptation is to vividly imagine the reward for waiting, which is often something better — with regards to saving money and other long-term goals.
They discovered that the hippocampus plays a key role in resisting temptation. That’s because when presented with the option to take something now, or something better later, the hippocampus goes to work crafting an image of what we will look like with the better option, and helps us assess the value of waiting. “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,” lead author of the study Dr. Mathias Pessiglione, of the Brain and Spine Institute in Paris, told Medical News Today.
The study involved two separate experiments. In the first one, researchers asked 15 participants to choose between a reward now and a better one later. The reward they would get right away was shown in a photo, while the reward they would receive for waiting was written down. By doing this, the participants were forced to imagine what their reward would be. Those who imagined their rewards with more detail were more likely to wait.
Next, the researchers asked another 20 participants to do the same task, however, these participants had a magnetic resonance imaging (MRI) scanner monitoring hippocampus activity. All participants showed consistent levels of impulsiveness to the first study no matter the rewards. There were also higher levels of activity when the immediate rewards were in photos and the future rewards were written down, compared to when both options were shown as photos or in text, supporting the researchers’ theory.
How Patients With Damaged Hippocampuses Reacted
They also did the same experiments on patients with Alzheimer’s disease and a behavioral variant of frontotemporal dementia (bvFTD), both of which affect hippocampus function. Alzheimer’s patients tended to choose immediate rewards when the better choices were written down. Meanwhile, patients with bvFTD were more impulsive with their decisions — impulsiveness is a characteristic of that particular type of dementia. “People 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 in the long run,” Dr. Pessiglione told Medical News Today.
Although the researchers called the hippocampus the most likely reason for these behaviors, they also noted that other brain regions had atrophied as well, including the parietal cortex, “therefore the study cannot be conclusive on hippocampus contribution to choice impulsivity.” In other words, the study did not prove causality. Also, the small amount of subjects warrants a larger investigation, they said.
Alzheimer’s disease affects as many as 5.1 million Americans. It impairs their ability to carry out simple behaviors as it destroys the parts of their brains associated with memory, thinking, and reasoning skills. Symptoms usually begin to appear in people once they turn 60 years old, however, it can also appear in people as young as 30 years old — early-onset Alzheimer’s affects less than five percent of people with the disease, according to the National Institutes of Health.
Source: Lebreton M, Pessiglione M, Fossati P, et al. A Critical Role for the Hippocampus in the Valuation of Imagined Outcomes. PLOS Biology. 2013.