A team of psychologists and physicists from Germany have found that variations in two messenger substances in the brain affect both short and long-term strategic decision making.
For the study, the researchers homed in on two neuronal messenger substances involved in decision making- GABA and glutamate. While GABA is known to have an inhibitory role in neural transmission, glutamate is excitatory. In the study, the researchers focused on how the ratio between the two in different parts of the brain is associated with decision making.
To conduct their experiment, they recruited 29 participants. Each was presented with two kinds of decisions. One was a reward-based decision, such as choosing a coffee on the way to work depending on factors such as price, quality, and whether the cafe is on the way.
The other decision was known as a ‘patch-leaving decision’- a long-term strategic consideration that involves balancing immediate costs against long-term gain. For example, a new job in another city may offer a higher salary and more exciting work but may also involve stress in finding a new place to live, a loss of social contacts, and higher rents.
The researchers used magnetic resonance spectroscopy to assess the excitatory/ inhibitory balance in each participant’s brain as they navigated through these situations. They then used this data to correlate the ratio of the two messenger substances to decision-making behaviors.
Amid reward-based decision tasks, the researchers found that participants with higher ratios of GABA to glutamate in their ventromedial prefrontal cortex (previously shown to be involved in reward-decision making) more reliably selected the higher-value option.
Meanwhile, in the patch-leaving scenario, participants with higher ratios of GABA to glutamate in their dorsal anterior cingulate cortex (previously shown to be involved in such decision making) were faster to leave resource-depleting situations. Those with higher concentrations of glutamate, however, required greater advantages to move from their current situation to another.
“Our results show a correlation between decision-making behavior and the balance of two messenger substances in the brain. People with a higher ratio of excitation to inhibition in dACC need a bigger incentive to move away from their status quo. By contrast, people with more GABA in vmPFC exhibit greater accuracy for short-term decisions.” says Luca Kaiser, one of the study’s authors.