‘Catastrophizing’ is described by pscyhologists as cognitive distortion. If you tend to predict the worst case scenario and then leap to the conclusion that a catastrophe will result, you would be considered a catastrophizer. In a new study published in the Proceedings of the National Academy of Sciences, researchers from University College London have identified the habenula as the part of your brain responsible for predicting negative events. They also believe this cell mass, which is about half the size of a pea, may play a role in our ability to learn from bad experiences. “The habenula tracks our experiences, responding more the worse something is expected to be,” said senior author Dr. Jonathan Roiser of the UCL Institute of Cognitive Neuroscience.
Previous neuroscience studies have shown how animals will exhibit avoidance behaviors following activity in their habenulas. Researchers watched as cells fired within animals’ habenula whenever bad things happened, or were simply anticipated to occur. Activity in this region is known to suppress dopamine, a neurotransmitter that helps regulate our brain’s reward and pleasure centers. Dopamine not only enables us to see rewards, but also to take action and move toward them. Significantly, the habenula has also been linked to depression.
For the current study, the researchers positioned 23 healthy volunteers inside a functional magnetic resonance imaging (fMRI) scanner and collected high-resolution brain images of activity in the tiny habenula. Then, volunteers observed a random sequence of pictures, each followed by figures depicting the chance of a good or bad outcome. Occasionally, volunteers pressed a button simply to show they were paying attention. Watching, the researchers discovered how habenula activation tracked the changing expectation of bad and good events. In particular, Roiser noted how the habenula didn’t just express whether something would lead to a negative event or not, it also signaled (with its increased activity) “how much bad outcomes are expected.”
“Fascinatingly, people were slower to press the button when the picture was associated with getting shocked, even though their response had no bearing on the outcome,” said Dr. Rebecca Lawson of the UCL Institute of Cognitive Neuroscience and lead author of the study. “This demonstrates a crucial link between the habenula and motivated behaviour, which may be the result of dopamine suppression.”
The habenula has previously been linked to depression, and this study shows how it could be involved in causing symptoms such low motivation, pessimism and a focus on negative experiences. A hyperactive habenula could cause people to make disproportionately negative predictions.
The researchers believe their study suggests how a hyperactive habenula might cause people to make disproportionately negative predictions, while also being involved whenever people feel pessimism and low motivation, or when they focus on negative experiences. “Other work shows that ketamine, which has profound and immediate benefits in patients who failed to respond to standard antidepressant medication, specifically dampens down habenula activity,” Roiser said. Learning more about the habenula, then, might someday lead to better treatments for depression.
Source: Rebecca P. Lawson, Ben Seymour, Eleanor Loh, Antoine Lutti, Raymond J. Dolan, Peter Dayan, Nikolaus Weiskopf, and Jonathan P. Roiser. The habenula encodes negative motivational value associated with primary punishment in humans.Proceedings of the National Academy of Sciences, 2014; DOI:10.1073/pnas.1323586111