Warhead summary

Before we begin our tour of the brain, we need to understand an essential concept: the model.

All organisms, not just humans, benefit from having models. In basic terms, a model is a process describing how senses can be linked to actions. This helps the organism to achieve its goals, and stay alive. For example, a bird has a model of where to locate its invertebrate prey, allowing it to find food.

Human brains also use models to process data, and send commands. This happens in the very base of the brain: the brainstem. 

The lowest part of the brainstem is called the medulla. If the medulla dies, you die. That’s because it’s responsible for monitoring our life support systems, and sending messages to control things like breathing and heart rate. It uses models to keep us alive.

The brainstem also helps us to respond flexibly to situations – pain, for example. The capacity to feel pain is important – again, it helps us not to die. But there are some situations where it’s helpful to dial it down. During the Second World War, for instance, many injured soldiers claimed not to feel pain. Their brains were able to respond flexibly, protecting them from pain when it was helpful to do so.

Higher up in the brainstem is a group of cells that manufactures an important molecule: dopamine. Dopamine is often thought of as a “pleasure” chemical, something that makes us feel good, a reward. To some extent, that’s true. But as we look at another feature of the brain, we’ll see that the full picture is a bit more complicated.

As we mentioned earlier, our brains use models to process data, and send commands. When they do this, they also make predictions about the data they’re receiving. Sometimes, the predictions are wrong. The brain then uses these prediction errors to update its models – to learn, in other words.

What does this have to do with dopamine? Well, prediction errors affect our dopamine, which means they can have a huge impact on how we feel and react. Let’s look at another example to understand this effect in the context of war.

During the First World War, the German air raids on London were relatively small-scale attacks. However, they were also totally unexpected, resulting in prediction error, and a devastating psychological impact. When London was bombed again, during the Second World War, people had been warned. The attacks were “predictable,” to a certain extent. So even though they were destructive, they were less damaging on a psychological level.

Another example of prediction error can be seen in France’s response to the German Blitzkrieg, or “lightning war,” in 1940. The suddenness of the German attack – with a combination of tanks, airborne troops, and special forces – came as a total surprise. The French army was caught off guard, and quickly surrendered. There are reports of military leaders in tears, in a state of psychological breakdown.

According to the historian Ernest May, “The scale and suddenness of Germany’s victory has to be explained primarily, I believe, as a result of the surprise achieved.” Or, from a neuroscience perspective – the French army was defeated by prediction error.