The brain
The brain processes information and informs behaviour
One of the main purposes of the brain is to enable us to navigate the world. We can think about it as an information processing device (a bit like a computer). This means that through our senses (seeing, hearing, touch, smell and taste), we get information about the world around us. The brain then makes sense of this incoming information and responds through our behaviour.
So, for example, what happens if you see a spider? The visual information (the image of a spider) goes from your eyes to the area of your brain in charge of processing vision – the visual cortex. Your brain then sends signals to other parts of the brain, which interpret the information and recognise that this is an animal, more specifically a spider. Now that you know this information, you need to decide what to do next. Will you run away? Or will you take a step closer to examine what kind of spider it is? Perhaps you don’t like spiders, and so decide to run away. That is, in essence, what the brain does: it receives information, processes it in a meaningful way and then allows us to act upon it.
The brain is the most complex organ in the body. It has over 86 billion brain cells, called neurons, which work closely together to form different brain areas. These brain areas communicate with each other to exchange information, forming networks within the brain.
In OCD, networks known as the frontostriatal loops are thought to be especially important. Each person’s brain has several different frontostriatal loops. These connect brain areas in the so-called prefrontal cortex with areas deeper in the brain (for example the striatum) allowing for an exchange of information in a back and forth manner – therefore, a ‘loop’. The frontostriatal loops are very important in prioritising information, and in selecting between competing bits of information – essentially, they decide what is important, and what is not.
To help us to think about what they do, imagine a frontostriatal loop as a busy traffic junction – there are cars, bikes and pedestrians that need to be managed effectively for the traffic to move smoothly. Traffic light signals help to direct how the traffic flows. In the brain, the frontostriatal loops control the information flow – allowing certain information to go, while stopping others. It can even prioritise specific types of information, over others, effectively determining what reaches its destination quicker.
The frontostriatal loops control the information flow and thus make the call on how we respond in a certain situation: whether to approach or avoid something, what information to focus on, or whether to continue thinking about something or move on. These loops have a big impact on how we react. So, if we see a spider, our frontostriatal loops will help us to move closer or run away.
Within the frontostriatal loops, brain chemicals, called neurotransmitters are very important and can change how the loops work. Neurotransmitters act as messengers in the brain and allow brain cells to talk to each another. Different levels of neurotransmitters, like dopamine or serotonin, can change how we make decisions.
These frontostriatal loops also play an important role in OCD. We’ll explore more about these loops and OCD later on.
Diverse influences make each brain unique
Although all brains follow these general principles of information processing, it is important to note that each one of our brains is unique and processes things differently.
No two brains are exactly alike, and each person’s brain constantly changes throughout their lifetime. When we are born, our brain is only a fraction of its final size, and it will grow and become increasingly complex and sophisticated throughout childhood, adolescence, and into adulthood. In particular, the brain regions that are part of the frontostriatal loops are some of the last areas to fully develop, usually not until late adolescence. This may play a critical role in the emergence of conditions such as OCD. You can find out more about this in the next section.
The changes that our brain goes through are influenced by many different factors. One of these factors is our genes – the biological building blocks that we receive from our parents. Genes will, to some extent, determine how our brains are built. But they are not the only influence. We know that the environment also has a big impact on our brain – everything we see, experience and do throughout our life has an effect on our brain. For example, learning how to play the piano can affect the brain in both structure and function, in order to support the coordination of very detailed finger movements that are needed in piano playing. This means the brain is not a static organ, but a very dynamic one. It adjusts to demands and what it has been exposed to. This is known as plasticity – the brain’s ability to change. All influences on the brain, both internal (such as your genes or changes of your hormones and neurotransmitters), and external (such as learning new skills), have a substantial effect on the brain and how it works.
All of this means that each of our brains is unique. Researchers are currently looking into how differences in the way that our brains work can lead to OCD. In the same way that all of our brains are very different, the reasons underpinning OCD may also differ from person to person. We explore this in the next section.