When communication between two regions of the brain is disrupted, we become more indecisive about value or preference decisions – such as choosing a new laptop or what dish we fancy on the menu.

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Preference decisions are less stable when the information flow between the two brain regions is disrupted.
Image credit: UZH

However, disruption of this communication does not affect the quality of objective or sensory decisions, such as deciding whether melons are bigger than cherries.

These were the findings of a neuroeconomics study recently published in the journal Nature Communications.

Neuroeconomics is a relatively new field that investigates the brain science behind decision making. The field is growing, as economists and business people show increasing interest in how the brain works.

In their study, Christian Ruff, a neuroeconomics professor at the University of Zurich (UZH) in Switzerland, and his team found that the intensity of communication between different regions of the brain determines how decisive we are in making value or preference-based choices.

Value or preference-based decisions are distinct from perceptual or sensory-based decisions. We make preference-based decisions when we choose a new car, a new dress or a dish from the menu. Later, we might wonder if we have made the right choice.

Sensory-based decisions are less prone to indecisiveness as they require a more straightforward assessment of the properties of what we are considering. For example, is this car a darker blue than the one I saw earlier?

Prof. Ruff and colleagues wanted to investigate why some people seem to be very decisive about their preference-based choices – they appear to know exactly what they want – while others seem to dither and hesitate.

They discovered that the precision and stability of preference-based decision relies not only on the level of activity of one or more brain regions, but in the intensity of communication between two particular brain regions.

The two regions – the prefrontal cortex just below the forehead and the parietal cortex just above both ears – are involved in representing our preferences and in spatial orientation and action planning.

To arrive at this discovery, the team invited volunteers to make preference- and sensory-based decisions about food while they underwent a noninvasive type of brain stimulation called “transcranial alternating current stimulation.”

Transcranial alternating current stimulation works by sending alternating currents through the skull to generate coordinated patterns of activity in particular brain regions.

The subjects were shown pictures of food items and asked to choose which they would prefer to eat at the end of the experiment (preference-based decisions) and also to decide, for example, whether one picture had more black in it than another (sensory-based decisions).

Using the stimulation technique, the researchers intensified or reduced the information flow between the prefrontal cortex and the parietal cortex as the volunteers were asked to make their choices. Prof. Ruff describes what they found:

We discovered that preference-based decisions were less stable if the information flow between the two brain regions was disrupted. Our test subjects were therefore more indecisive. For the purely sensory decisions, however, there was no such effect.”

He and his colleagues conclude it seems that “communication between the two brain regions is only relevant if we have to decide whether we like something and not when we make decisions based on objective facts.”

The team found they could not make decisions more stable by intensifying the information flow between the two regions. But they note this could be because the volunteers were all young, healthy people with highly developed decision-making skills.

It falls to further research to find out if the technique might be useful in a therapeutic capacity, say the researchers. – for example, to discover if it might help patients with very high impulsiveness or indecisiveness, perhaps as a result of a brain disorder or injury.

Earlier this year, Medical News Today learned how brain scans of shogi players gave new clues about intuitive strategy decision making. In Nature Neuroscience, a team from the RIKEN Brain Science Institute in Japan describes how different regions of the brain separately encode the values of offensive and defensive strategies as players assess different board layouts of the Japanese chess game.