Learning, remembering, forgetting

How does the brain learn in everyday situations, or in a classroom?

Well, that’s like the trickiest question you could have asked! There are lots of learning systems in the brain, and it’s likely we use all of them to do what we call LEARNING in the classroom.

In the film the Matrix, when Neo is in the virtual world, he can instantly be given new skills and knowledge. It’s just like uploading a new program to a computer: install and go! Need martial arts? No problem, install and go. Need to fly a helicopter? Upload and go. But the brain takes much longer to learn. Why is that?

For the brain to learn, it needs to change the way neurons get activated by situations in the future. Mostly this is done by changing the strength of the connections between neurons; a bit by changing how ready particular neurons are to fire (their ‘resting’ activity levels). There are three reasons why this can’t be done instantly like in the Matrix. First, no one has the computer program to upload or, indeed, a way of uploading it. The program must be worked out by the brain from the situations it is exposed to. Second, mostly, learning isn’t about memorising specific moments. What needs to be learned is often skills or concepts that have to be flexibly applied. It takes time to experience the range of situations to which the new knowledge is to be applied. Third, depending on the learning system involved, the connections change at different rates, some slower than others.

There are at least eight learning systems in the brain (depending on how you count them).

1. Episodic. There is indeed a system for memorising specific moments, which produces your so-called episodic or autobiographical memory (e.g., what happened yesterday). This is the hippocampus and the structures around it. This system can change its connections very quickly to record snapshots.

2. Concepts. The brain learns associations between knowledge, between perceptual information and motor responses. It spots complex patterns within this knowledge, so-called ‘concepts’. This happens within the cortex, the outer layer of the brain, where changing connections take hours.

3. Conditioning. Some associations are unconscious and involve the emotion (limbic) structures further inside the brain. When I ate mushrooms that one time, I felt sick. Now I won’t eat mushrooms. Thinking about them makes me nauseous. Psychologists have called these kinds of associations ‘classical conditioning’.

4. Control. The modulatory system in the prefrontal cortex learns how to activate and deactivate the appropriate specific systems in the back of the brain to carry out tasks, and it learns how to negotiate with the limbic system so that emotions can be integrated with plans and goals.

5. Reward-based. There’s a system that works out what you have to do to get what you want, to make nice things happen and avoid bad things. It’s called the reward-based system, and it likes to use the dopamine neurotransmitter system.

6. Procedural. There’s the procedural learning system. This is for learning activities that we perform frequently and often unconsciously, such as tying shoelaces, reading, reciting times tables, or driving a car. These automatic skills can take tens or hundreds of hours to learn through practice – repeating the complex activity over and over again until all of the relevant neural systems work together so it can be performed fluently and unconsciously, whether it’s a motor skill or thinking activity. The structures involved are the looping outer-to-inner circuits connecting the cortex through the basal ganglia to the thalamus and back again, and the cerebellum.

7. Observation. The brain can take advantage of its widespread circuits for perceiving and understanding other people. Skills can be learned simply by observing other people, so-called ‘modelling’. You watch videos of Michael Jackson moonwalking, and then you have a go yourself.

8. Instruction. The brain can take advantage of its widespread circuits for using language to construct new concepts and plans. Skills can be learned through instruction.

Instructions for moonwalking:

Step 1: Start with your feet together.

Step 2: Raise your right heel so that you’re standing on the ball of your right foot.

Step 3: Shift your weight onto that still raised right foot so that the left one feels weightless.

Step 4: Slide the left foot backwards.

Step 5: Drop the right foot flat and raise your left heel in a snap motion.

Step 6. Repeat on the other side.

These learning systems are integrated and continuously interacting.

The older you get, the less learning has to start from scratch. In young infants, toddlers, and children, a lot of learning is figuring out the basics, what objects look like, what movements are useful, what is fun, how social situations work. But from late childhood onwards, more of learning is understanding how a new situation is similar to what you already know, so previous knowledge can be adapted. Say you start playing a new computer game – images appear, you must respond in some way. Then you figure out, ah, I see, this game is a bit like Tetris. Then the modulatory system (the prefrontal cortex) can enhance the relevant perceptual information that is going to be useful (shapes, rotational movement) and prime motor actions (button presses to achieve shape alignment). After that, improvement on the game will be about fine-tuning this template. If you spot the similarity to Tetris, or someone is kind enough to tell you, this is another type of learning that uses what you already know: learning by analogy.

The brain has an overarching principle for learning: Try to make all processes automatic – so they occur quickly, smoothly and without need for cognitive effort or even awareness. Ideally, there should be no involvement of the modulatory system controlling which bits do what and when, because this is slow, the modulatory systems gets tired, and it can get distracted if it has to do too many things at once.

The more knowledge/skills are used, the more they will become automatic. By the same token, the less they are used, the more the skill or knowledge is likely to be lost. Forgetting happens differently in different learning systems. In the limbic system, the amygdala doesn’t readily forget what situations made it anxious. This information can be overwritten using therapies like progressive de-sensitisation (see, play with lots of cuddly spiders, they aren’t so bad after all!). As we saw earlier, the hippocampus fills up with episodic memories every three months and memories have to be shipped out to cortex for more permanent storage. The cortex itself is use-dependent and over time, the details of knowledge will blur without use. Repeating the learning experience later helps to preserve the knowledge. Procedural learning, by contrast, is hard won. Skills take extensive practise to acquire but decline slowly and are readily retrained. Twenty years after you last tried it, you can still ride a bike, after a few wobbles.

Knowledge can be put into the brain, but does it always come out when you need it? Part of learning is establishing strategies for retrieving the knowledge in the right situations (like answering an exam question). Activating the appropriate knowledge in context is the job of the modulatory system (the prefrontal cortex). Learning activities that build stronger pathways between prefrontal cortex and the specialised structures in the rest of the brain improve access to knowledge – activities such as elaborating or organising knowledge, or explaining the ideas to yourself and others.

It’s complicated, isn’t it, and that’s just learning. If we think about teaching, well there are whole rafts of other aspects we have to consider. It’s not just about a teacher exposing a pupil’s brain to the situation where it can program itself. Sometimes, more complex concepts build on simpler concepts, so the teacher must lay a trail of breadcrumbs, an order in which situations must be presented to learn progressively more complex ideas.

There are physical factors, such as possible distractions of other pupils chatting, visual distractions of interesting things to see around the classroom. There are social factors: peer dynamics, working with social partners to learn through problem solving. There is the role of feedback and rewards from the teacher and their effect on pupil motivation – ultimately influencing the unconscious calculation each pupil makes: ‘how long and hard long should I work on this task, based on my estimation of whether I am likely to succeed?’ And there’s the role of emotions, such as the sense of belonging, which increases effort and decreases distracting thoughts of inadequacy or alienation.

What should we take from all this? Perhaps a new appreciation for teachers when they have to assess how well learning is taking place in the classroom. Inside the brain, learning is the most complicated process there is.