Are We Hardwired to Say “No” When Facing Difficult Decisions?

by Monica Joshi

When faced with difficult decisions, people react in a myriad of different ways. While some people like to bury their heads in the sand and try not to think about the problem until it's too late, others tackle the issue head-on and try to solve the problem. What all of us have in common, apparently, is that when faced with difficult decisions, we are hardwired to say “no”.

It might not even be your fault, as new research shows that even if the “Go” and “No Go” signals in our brains compete, the deck is stacked against the “Go” neurons. The new computational model based on data from rodent brains was created by Arvind Kumar, a researcher at the Department of Computational Biology at KTH Royal Institute of Technology in Sweden and the senior author of the study.

According to Kumar, one of the main reasons why we might be geared to respond with “no” is that D1 ("Go") neurons and rival D2 ("No Go") neurons are projected in pathways within the stratum that inhibit each other. It turns out that the D2 neurons exert more inhibition on the D1 pathway as opposed to the other way around.

The bias is created via an asymmetric connection between the two circuit neurons. The D1 neurons require slightly higher input than the "No Go" pathway, as this pathway is stronger. The D1 neurons, however, can overcome the D2 pathway only when they receive weak inputs from the cerebral cortex, which generates functions such as sensory perception, motor command, conscious thought and language perception. In other words, the decision transition threshold can be raised depending on the cortical input, as the cerebral cortex is responsible for higher brain functions such as thought and action.

Jyotika Bahuguna, the lead author of the study and a joint PhD student at KTH and Bernstein Center in Freiburg, Germany said:

"This threshold where you are likely to switch your decision from "Go" to "No Go", is created by unequal connectivity. If the connectivity were identical then such a threshold would not arise."

This model of the "Go" and "No Go" pathways is quite important for further research on the cognitive problems associated with the basal ganglia dysfunction. This dysfunction can cause problems with a person's ability to control speech, movement or posture. A person with basal ganglia dysfunction may have serious trouble starting, stopping or even sustaining movement. In particular, this dysfunction is highlighted in those with Parkinson's disease and Tourette's syndrome.

The research could shed light on the way that new treatment could be developed for those with basal ganglia dysfunction. In addition to this, however, it will be vital to see if the "Go" and "No Go" computational model can be tested directly in human brains, using a different method but a similar model.