Stress can affect how brain learns something new: study

Researchers from the Ruhr-Universitat Bochum found that when performing a new task a brain region that is responsible for unconscious learning gets activated in stressed people, while in non-stressed people the part of the brain which is important for long-term memory gets activated.

The study included data from 59 subjects. Half of the participants had to immerse one hand into ice-cold water for three minutes under video surveillance. This stressed the subjects, as hormone assays showed.

The other participants had to immerse one of their hands just in warm water. Then both the stressed and non-stressed individuals completed the so-called weather prediction task.

The subjects looked at playing cards with different symbols and learned to predict which combinations of cards announced rain and which sunshine.

Each combination of cards was associated with a certain probability of good or bad weather. During the weather prediction task, the researchers recorded the brain activity with MRI.

Both stressed and non-stressed subjects learned to predict the weather according to the symbols. Non-stressed participants focused on individual symbols and not on combinations of symbols.

They consciously pursued a simple strategy. The MRI data showed that they activated a brain region in the medial temporal lobe- the hippocampus, which is important for long-term memory.

Stressed subjects, on the other hand, applied a more complex strategy. They made their decisions based on the combination of symbols. They did this, however, subconsciously, they were not able to formulate their strategy in words.

In the case of the stressed volunteers the so-called striatum in the mid-brain was activated- a brain region that is responsible for more unconscious learning.

"Stress interferes with conscious, purposeful learning, which is dependent upon the hippocampus. So that makes the brain use other resources. In the case of stress, the striatum controls behaviour - which saves the learning achievement," concluded Schwabe.

Non-stressed individuals applied a deliberate learning strategy, while stressed subjects relied more on their gut feeling. "These results demonstrate for the first time that stress has an influence on which of the different memory systems the brain turns on," Dr Lars Schwabe cognitive psychologist said in a statement.

The study was published in the Journal of Neuroscience.