This post is also available in Dutch.
Calling someone on the phone is simple and fast, but at the same time many different complex communication processes are quickly going on in your brain.
It’s Wednesday afternoon and your phone is ringing. You check the screen and see it’s your mother. You decide to pick up. You chat for about 30 minutes about your past week before saying goodbye and agreeing to talk again next week. Nothing special, right? But your brain has been incredibly busy during this half hour!
It started when you answered the phone. While this may seem trivial, it’s actually quite a feat that your brain was able to register the sound and connect it to the phone you saw. While the brain area for hearing is at the side of your head, roughly at the height of your ears, the brain area responsible for seeing is actually at the back of your head (so we really do have eyes in the back of our heads). That means the two areas need to communicate in order to combine visual and auditory information.
How do brain areas communicate?
This communication happens via nerve fibres that we call white matter tracts or axons. White matter in the brain compares to a highway, along which many types of information can be transported from one area to another at high speed. Similar to highways, connections come together at multiple points and can cross each other.
This transfer of information through the brain is incredibly fast. You don’t even notice how different streams of information originating from different locations are combined. These speeds are made possible by a thin layer of fatty tissue covering the axons in the brain called myelin. Myelin protects the axons from damage and keeps the signals in different axons apart. Moreover, without myelin a signal would be transported at 2 meters per second, while with myelin this becomes an impressive 100 meters per second. Mind you, that’s 360 km or 223.7 miles an hour! Because of this speedy information transfer, in the situation above you are able to combine the information that enters through your eyes and ears in about 100 milliseconds.
Retrieving information from memory
Communication between different brain areas is important to process different types of information from your environment, but that is not the whole story. In some situations, we also need to access information that has been stored in our brain at some earlier point in time. Imagine your mother asks about a meeting you had at work last week: your brain will immediately start retrieving this information to enable you to answer this question. There are two important areas in the brain involved in this process: the hippocampus and the neocortex, which consists of the top layer of our cerebrum and is a few millimeters thick. The hippocampus is located behind your ears, but deeper within your brain. It is regarded as the retrieval center of the memory system. The hippocampus is activated by things that happen to or around you and will subsequently get to work retrieving the correct piece of information from the neocortex. This information can then be used to give your mother an appropriate answer.
When you are making a simple phone call, the connections in our brain are working at full speed to process all the information coming from outside of your brain. But your brain is also working hard to retrieve relevant information stored within your brain. Think about that the next time you pick up your phone!
Marlies Hiemstra has graduated from the Master in Cognitive Neuroscience at the Donders Institute and likes to share all the extraordinary things she learned about the brain during her studies.