There are billions of neurons in the brain, and they have little gaps between them called synapses. The electrical signals travel across the gap from one cell to another. The brain gets signals from other parts of the body through nerve impulses – sensations like hot/cold, pain – and other information from our senses. Those trigger neurons to fire and make us associate those sensations with things that we’ve experienced before.
Scientists can do experiments called functional Magnetic Resonance Imaging where people’s brains can be studied as they focus on specific tasks. The technique measures bloodflow to different areas of the brain – if you’re using an area in a thought, it needs more blood. This means that scientists can work out what parts of the brain light up (become active) when we’re faced with specific information like an image of a friend, something we find disgusting or something we really like. The goal of this work is to answer the question how do we think.