Why does the brain use so much energy?

We know more about what the brain does when it's active than we do when it's at rest. It makes sense -- much neuroscientific research has looked to understand particular (and active) processes. James Kozloski, a researcher at IBM, has investigated what the brain does when it's resting -- what he calls 'the Grand Loop'. "The brain consumes a great amount of energy doing nothing. It's a great mystery of neuroscience," Kozloski told PopSci. He argued that around 90 percent of the energy used by the brain remained "unaccounted for".

He believes that the brain is constantly 'looping signals', retracing neural pathways over and over again. It's a "closed loop", according to Kozloski, meaning it isn't reliant on external inputs as much of the brain's activity is.

Kozloski tested his theory by running his model through IBM's neural tissue simulator and found that it could potentially account for genetic mutations such as Huntington's. He argued that information created by one mutated gene could, through the 'Grand Loop', affect an entire neural pathway.

Anxiety and energy

So what happens when our brain is at work? And how does expending energy affect our neural processes?

Much historic research into anxiety has found that people tend to exert more energy or force when they're being watched -- something that leads to slip-ups or mistakes under pressure. Musicians performing in front of crowds are more likely to forcefully press keys or pluck strings harder than they do when alone. Something similar is seen in all kinds of performance -- including learner drivers and sportspeople.

A new study, conducted by researchers at the University of Sussex, claims to have identified the neural system that causes us to stumble and make mistakes when we're trying to make a good impression.

Participants' brain activity was monitored by functional magnetic resonance imaging (fMRI) while they carried out a task requiring them to exert an exact amount of force when gripping an object. They were then shown video footage of two people they believed were evaluating their performance in the task. The task was then repeated -- only this time the video footage showed people who appeared to be evaluating somebody else's task.

Not only did participants report feeling more anxious when they believed they were being watched, they also gripped the object harder -- without even noticing.

Scans showed the inferior parietal cortex (IPC), an area that helps us control the amount of energy we use, became deactivated when people felt they were being observed. The IPC works with the posterior superior temporal sulcus (pSTS) to form what researchers called the "action-observation network" (AON). This area of the brain helps people infer what others are thinking based on facial expressions, body language and gaze.

The pSTS coveys this facial information to the IPC, which subsequently generates motor actions (such as those used to perform a song on piano, or execute a driving manoeuvre). If we feel observers want us to do well, the system continues to perform well. But if we're nervous, as participants in the study were, then our IPC is deactivated and our performance suffers. "We realised that AON might be related to performance anxiety because when being scrutinised, we tend to care about how the audience is feeling about us and our performance," said Dr Yoshie Michiko, lead researcher on the project.

The team stressed that self-belief was important, adding that people who suffer from nerves could benefit from practising in front of smaller groups first, or trialling performances on friends and family and asking them to applaud. "Such experience would help you to induce a desirable activation pattern in your brain and boost self-confidence," the report's authors explained.

This article was originally published by WIRED UK