“The brain circuit that makes most people natural optimists has been identified by scientists,” The Times reported on October 25 2007. The newspaper said the discovery that certain regions of the brain appear to be associated with “a rose-tinted view of the future”. This may provide “promising new insights into the origins of mood disorders such as depression and anxiety," it adds.
The story is based an experiment where MRI was used to compare images from peoples’ brains as they thought about positive and negative events both in the past and in the future. The study showed that there were differences in the activity in two particular areas of the brain when people thought about positive future events compared to thinking about negative future events. Though the study offers some insights into brain function when people imagine future events, treatments for “depression” based on these findings are a long way off.
Where did the story come from?
Dr Tali Sharot and colleagues from the Department of Psychology at New York University conducted this research. The study was funded by a grant from the National Institute of Mental Health and it was detailed in a letter published in the peer-reviewed medical journal Nature .
What kind of scientific study was this?
The research was an experiment that was conducted in 15 volunteers. Each participant was presented with 80 life episodes and asked to imagine these scenarios according to the instructions shown on a screen. They would either be past or future events and included scenes such as “the end of a relationship”, “winning an award” and so on. The participants were asked to press a button when the image (the “memory” or for future events, the “projection”) began to form in their mind, and again when they had finished thinking about it. After each image, the participants rated the scenario depending on its emotional arousal and whether they called it “positive”, “neutral” or “negative”. These categories were used later to compare the differences between the participants when they were thinking about positive and negative, future and past events. Brain activity throughout the sessions of remembering and imagining was determined using magnetic resonance imaging (MRI).
Finally, all of the scenarios were re-run and participants were asked to rate their experience of them, including how vivid they were, when they thought the event had happened or would happen. Participants then completed a questionnaire that assessed their personality trait of optimism to determine whether they were “optimistic” or “pessimistic” people.
What were the results of the study?
The study found that imagining future positive events led to increased activity in two particular regions in the brain – the amygdala and the rostral anterior cingulate cortex (rACC) – compared with imagining negative future events. Their observations suggest that people have an “optimism bias” and tend to expect future events to be less negative than their past experiences of similar events. Activity in the rACC in particular seemed to be associated with being an “optimistic” personality type.
What interpretations did the researchers draw from these results?
The researchers report that the study shows how differently the brain behaves when it is projecting positive future events. They report on particular regions of the brain involved in the recall of memories and in imagining future events. The researchers speculate that their findings may shed some light on the mechanisms that cause depression, which is often associated with pessimism and problems in imagining a hopeful future. They say that pondering on negative events may interfere with daily activities by “promoting negative effects such as anxiety and depression”.
What does the NHS Knowledge Service make of this study?
The following should be kept in mind when interpreting this study:
- This is a very small experiment (15 people). The majority of the people who were included turned out to be “optimistic” (averaging a score of 17.7 on a scale of 0–24 where 24 is the highest). Repeating the experiment in people who are not optimistic (pessimistic) would give us a better understanding of the difference in brain activity between these types of personalities. As they stand, the findings may not be able to be generalised to a much wider group.
- The link between the activities observed here and the breakdowns that may lead to depression are speculation. We support the researchers’ call for further research to determine whether the areas of the brain identified here and other regions involved in emotional processing may be responsible for diminished optimism associated with depression. Without these studies and a better understanding of the relationship between these areas in the brain and mental health, hopes for depression treatments based on these findings are a long way off.
- Recalling past events and projecting future ones involves a comparison between “remembering” and “imagining”. As the researchers note, their study cannot determine whether the “optimism bias” noted in the projection of future positive events just reflects a “tendency to engage in positive thought when not constrained by reality” (as one would be when remembering real events that happened).
It is certainly good to know that there is a recognised neural mechanism behind optimism and using this part of the brain for a moment, we might also hope that treatments for people suffering the burden of depression might be developed in future.
Sir Muir Gray adds...
This study confirms common sense – we know that the brain does the thinking and that different bits deal with different thoughts. Even before this we knew that we should help people think better, not just feel better.