A University of Cambridge study has revealed that a brain network previously thought to be confined to our inner thought processes, such as when day-dreaming, is crucial for enabling us to switch-to and operate-in autopilot.
Default mode network drives the brain’s autopilot
The default mode network (DMN) of the brain was previously thought to underlie internal thought processes such as thinking about the past, planning for the future, thinking creatively and, as previously mentioned, day-dreaming.
The DMN is made up of connecting higher-level brain areas. Active at times of rest, abnormal activity in this network has been linked to an array of disorders including Alzheimer’s disease, schizophrenia, attention-deficit/hyperactivity disorder (ADHD) and disorders of consciousness.
Classically, it is not considered to be involved in the processing of external information from the environment to enable the performance of tasks. However, a growing body of evidence suggests that it plays a more active role in task performance than previously thought. But, until now, it’s precise function has remained unclear.
Memory and learning recall enables autopilot to kick in
In a recent paper published in PNAS, Dr Deniz Vatansever, Prof. David Menon and Dr Emmanuel Stamatakis from the Division of Anaesthesia at the University of Cambridge, explored functional activity in the DMN’s of subjects in response to tasks that engaged their brains’ autopilot.
First author, Dr Deniz Vatansever, now at the University of York, explains: “We asked healthy participants from the local community with no previous history of neurological or psychiatric conditions, to lie inside an MRI scanner and perform simple tasks involving matching cards by colour, shape or number.”
However, the participants were not told the rules of the games, and instead had to figure them out for themselves by trial and error.
The authors observed the most interesting differences in brain activity occurred when comparing the learning, or acquisition stage with the application stage, where the participant was using their learned knowledge to complete the task. During acquisition, participants engaged the dorsal attention network areas of their brain, but during the application stage they engaged their DMN.
Importantly, during the application stage, participants who showed strong engagement and connectivity between their brain’s learning and memory centres and their DMN areas completed the tasks faster and more accurately than others.
As Deniz elaborates: “Our evidence suggests the default mode network is essentially like an autopilot that helps us make fast decisions when we know what the rules of the environment are. So, for example, when you’re driving to work in the morning along a familiar route, the default mode network will be active, enabling us to perform our task without having to invest lots of time and energy into every decision.”
The brain’s autopilot is energy efficient and confers an evolutionary advantage
When asked what the evolutionary advantage of an ‘autopilot’ system might be? Deniz suggested: “Although extensive research would be required to answer this question, an autopilot system would be beneficial for the conservation and efficient use of limited energy stores when interpreting and responding to the environment.”
Meaning, an autopilot system improves the energy economy in the brain. If we understand certain rules about the task at hand, or the environment in which we are in, we can devote less energy or attention to the brain areas overseeing the performance of these tasks by engaging our autopilot system, and can then redirect the surplus energy to the performance of other brain processes.
Deniz adds: “If this system, in fact, constitutes a memory-based internal model of the world around us, then we can expect/predict and respond in a fast and efficient manner, which would provide an adaptive advantage.”
The study authors suggest their findings could have implications for patients with brain injury as the integrity of the DMN has previously been correlated with levels of consciousness. However, in this study only people with ‘healthy’ brains were tested. Future work will explore the implications of these findings in people suffering with disorders of consciousness.
Vatansever, D, Menon, DK, Stamatakis, EA. Default Mode Contributions to Automated Information Processing. PNAS; 23 Oct 2017; DOI: 10.1073/pnas.1710521114