Scientists identify two brain networks influencing how we make decisions

February 2, 2017
Credit: Wikimedia Commons

Scientists at the Medical Research Council Brain Network Dynamics Unit at the University of Oxford have pinpointed two distinct mechanisms in the human brain that control the balance between speed and accuracy when making decisions.

Their discovery, published in eLife, sheds new light on the networks that determine how quickly we choose an option, and how much information we need to make that choice. A more detailed understanding of this intricate wiring in the holds the key to developing better treatments for neurological disorders such as Parkinson's disease.

The fundamental trade-off between speed and accuracy in has been studied for more than a century, with a number of studies suggesting that the subthalamic nucleus region of the brain plays a key role.

"Previous behavioural studies of decision making do not tell us about the actual events or networks that are responsible for making speed-accuracy adjustments," says senior author Peter Brown, Professor of Experimental Neurology at the University of Oxford. "We wanted to address this by measuring the exact location and timing of electrical activity in the subthalamic nucleus and comparing the results with behavioural data collected while a decision-making task is being performed."

Brown and his team first studied the reaction times of 11 patients with Parkinson's disease and 18 healthy participants, who were each asked to perform a moving-dots task. This required them to decide whether a cloud of moving dots appeared to be moving to the left or the right. The difficulty of the task was varied by changing the number of dots moving in one direction, and the participants were given randomly alternating instructions to perform the task with either speed or accuracy.

The researchers found that participants made much faster decisions when the task was easier - with the dots moving in a single direction - and when instructed to make a quick decision. They also found, in line with previous studies, that participants made significantly more errors during tests where they spent longer making a decision after being instructed to emphasise accuracy.

Using a computational model, they saw that it took longer in the more difficult tests for the brain to accumulate the necessary information to reach a critical threshold and make a decision. When the participants were asked to focus on speed, this threshold was significantly lower than when they focused on accuracy.

"The next step was to determine the activated networks in the brain that control these behavioural modifications and the trade-off between fast and accurate decisions," explains first author and postdoctoral fellow Damian Herz. "We measured the of groups of nerve cells within the subthalamic nucleus in patients with Parkinson's disease, who had recently been treated with . We found two distinct neural networks that differ in the way they are ordered and the way they respond to tasks.

"One network increases the amount of information required before executing a decision and is therefore more likely to be activated when is important, while the second network tends to lower this threshold, especially when the choice needs to be made quickly."

The findings add to the increasing evidence that the pre-frontal cortex region of the brain contributes to decision making and opens up further interesting avenues to explore.

"We know that changes in activity of one of the sites we identified is also related to movement control," adds Brown. "Close relationships between these could mean that a common signal is responsible for adjustments in both the speed of decision and of the resulting movement. A better understanding of these mechanisms might make it possible to focus therapeutic interventions on specific neural circuits to improve treatment of neurological disorders in the future."

Explore further: Study explains why mistakes slow us down, but not necessarily for the better

More information: Damian M Herz et al, Distinct mechanisms mediate speed-accuracy adjustments in cortico-subthalamic networks, eLife (2017). DOI: 10.7554/eLife.21481

Related Stories

Study explains why mistakes slow us down, but not necessarily for the better

January 21, 2016
Taking more time to make decisions after a mistake arises from a mixture of adaptive neural mechanisms that improve the accuracy and maladaptive mechanisms that reduce it, neuroscientists at New York University have found. ...

Brain activity predicts the force of your actions

November 24, 2016
Researchers have found a link between the activity in nerve clusters in the brain and the amount of force generated in a physical action, opening the way for the development of better devices to assist paralysed patients.

How the brain responds to choices

October 7, 2016
Choices, it is commonly understood, lead to action—but how does this happen in the brain? Intuitively, we first make a choice between the options. For example, when approaching a yellow traffic light, we need to decide ...

Timing may be key to understanding cognitive problems in Parkinson's disease

December 15, 2016
When a cheetah chases a gazelle, it's not raw speed that predicts the outcome of the contest. Instead, it's the animal that times its movements better that has the advantage. That ability to consciously guide movements over ...

Ever-so-slight delay improves decision-making accuracy

March 7, 2014
Columbia University Medical Center (CUMC) researchers have found that decision-making accuracy can be improved by postponing the onset of a decision by a mere fraction of a second. The results could further our understanding ...

Brain mechanisms in drug addiction—new brain pathways revealed

November 24, 2016
UNSW researchers have identified new brain pathways linked to addiction and shown that by manipulating them, drug seeking behaviour and motivation for alcohol can be reduced.

Recommended for you

Researchers create tool to measure, control protein aggregation

October 22, 2017
A common thread ties seemingly unlinked disorders like Alzheimer's disease and type II diabetes together. This thread is known as protein aggregation and happens when proteins clump together. These complexes are a hallmark ...

'Selfish brain' wins out when competing with muscle power, study finds

October 20, 2017
Human brains are expensive - metabolically speaking. It takes lot of energy to run our sophisticated grey matter, and that comes at an evolutionary cost.

Want to control your dreams? Here's how

October 19, 2017
New research at the University of Adelaide has found that a specific combination of techniques will increase people's chances of having lucid dreams, in which the dreamer is aware they're dreaming while it's still happening ...

Researchers find shifting relationship between flexibility, modularity in the brain

October 19, 2017
A new study by Rice University researchers takes a step toward what they see as key to the advance of neuroscience: a better understanding of the relationship between the brain's flexibility and its modularity.

Brain training can improve our understanding of speech in noisy places

October 19, 2017
For many people with hearing challenges, trying to follow a conversation in a crowded restaurant or other noisy venue is a major struggle, even with hearing aids. Now researchers reporting in Current Biology on October 19th ...

Investigating the most common genetic contributor to Parkinson's disease

October 19, 2017
LRRK2 gene mutations are the most common genetic cause of Parkinson's disease (PD), but the normal physiological role of this gene in the brain remains unclear. In a paper published in Neuron, Brigham and Women's Hospital ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.