Here’s a link to the New Scientist article on the free energy principle. I also read Friston’s – the author of the theory – paper but even with my physics background I had a hard time understanding it.
The free energy principle of the brain comes down to minimizing the amount of prediction error that you make day to day.
As a simple example, take what happens when you glimpse an object in your peripheral vision. At first it is not clear what it is - or, as Friston [the theorist who came up with the idea] would put it, there’s a big error between your brain’s prediction and what it senses. To reduce this prediction error, Friston reasoned that one of two things can happen: the brain can either change its prediction or change the way it gathers data from the environment. If your brain takes the second option you will instinctively turn your head and centre the object in your field of view. “It’s about minimising surprise,” he explains. “Mathematically, free energy is always bigger than surprise, therefore if you can minimise free energy you can avoid surprising encounters with the world.”
I find this very appealing because it can be applied to all different types of brain activity. One covered in the article is neural plasticity:
Neuron A “predicts” that neuron B will respond to the stimulus in a certain way. If the prediction is wrong, neuron A changes the strength of its connection to neuron B to decrease the prediction error. In this case the brain changes its internal predictions until it minimizes its error, and learning or memory forming is the result.
Friston has done some experiments showing that visual perception closely matches this idea of minimizing free energy. He’s also looking to cut out the ‘top’ of the brain, or the higher functioning cortex involved in planning, with TMS and seeing if the lower more primal neurons act in accordance with this theory.
I think this model shows nicely how the brain reacts to the environment. However there still seems to be a hole as the ultimate theory because we can consciously choose to disobey this law. We don’t usually because it’s much more useful to minimize surprise day to day, but the fact remains that we can.