What is the brain’s most important job?

Not thinking. Not feeling. Not making us feel happy or sad, In fact it’s not any of the jobs you may associate with being human.

The brain’s most important job is running a budget for your body.

Every thought we have, every action we take, every move we make is ultimately done in the service of regulating your body. The brain uses 20% of its oxygen at rest, and two thirds of that are used for sending signals up and down the neural pathways. The brain responds to two kinds of signals; those from the outside world (proprioceptive) and those from the body itself (interoceptive).

The brain uses incoming sensory data to estimate the body’s state and anticipate what will happen next. Upon predicting a demanding situation the brain will respond by signalling to the body’s resources – changing blood pressure, secreting hormones and metabolising glucose – in order to meet those needs.

A prediction machine

The brain functions as a prediction machine, anticipating the needs of your body and meeting those needs before they arrive. A bit like looking out the window in the morning, anticipating rain and picking up an umbrella, the brain assesses the needs of the body. Although unlike selecting the correct clothes for the forecasted weather, your brain is budgeting resources like glucose, oxygen, salt and all the other nutrients it needs.

The technical term for this is allostasis. However, because humans have limited resources, every movement we take and every new thing we learn, draws upon these resources and the brain has to ask itself – is this a good investment?

Just like any company, the brain keeps track of the accounts within the body to ensure the overall budget is balanced. To maintain long-term good health, a brain must make additional investments in glucose and other resources such as sleep, exercise and activities that improve allostasis.

So what happens when the budget runs into a deficit?

Sometimes your body might go into the red as a result of an unexpected expenditure, such as, exposure to serious infection (hello Covid!), staying out all night, or experiencing a traumatic event. In some cases these expenditures might compound over time as is seen in Adverse Childhood Events, racism, domestic abuse and bullying.

When your body budget is overdrawn for too long your immune system pays the price – a chronic overdraft in your body budget sets the scene for chronic illness.

What happens when the brain is in debt?

Financial deficits create biological deficits. Unlike a shopaholic who doesn’t know when to stop, when the brain is in debt it stops spending.

The two most expensive things to the brain are learning something new and moving the body, so if you continue to try and spend BIG, using an already overdrawn body budget, this can lead to fatigue, post-exertional malaise and cognitive impairment.

So what can we do to keep our body budget in balance?

Focus on simple activities that keep your body budget in credit. Adequate sleep, nutrition, movement (mindful movement is great!), getting out in nature, soothing activities and practices, such as learning to breathe optimally, all increase our brain’s ability to run the body budget smoothly and efficiently.

It’s not really brain science…is it?

This post is inspired by Neuroscientist Lisa Feldman-Barrett’s amazing book: Seven and a Half Lessons about the Brain.