How does an image of the world reach our consciousness, and how does it reach the deeper layers of the psyche? The rules that govern the “grey tissue between your ears” are explained by Dr Paweł Boguszewski, a researcher at the Nencki Institute of Experimental Biology.

It was evening. Lying on the couch in front of the television, Klara surfed channels mindlessly. Suddenly there appeared on the screen the face of a well-known politician, twisted into a grimace. The man was shouting something from a lectern, shaking his fist, threatening something. “What nonsense,” Klara murmured, disgusted, stabbing her thumb down on the remote to switch off the set.

This scene plays out every day in thousands of homes around the world. Nothing special. But for a neuroscientist these few seconds are a fascinating event, showing what a wonderful work of evolution the human mind is – along with the whole nervous system. Between the appearance of the threatening face on the screen and the set being switched off, extraordinary things happen in Klara’s nervous system, and most of all in her brain. Let’s try to look at each of these phenomena in order.

In complexity, strength

The mind is the most complicated system we know. It’s made up of about 86 billion neurons, cells that specialize in processing and transmitting information. They carry sensory impressions from the periphery of our bodies to the centre, perform complex analyses and comparisons, record information for future use and send commands to the muscles.

Each neuron is exceptional, changing under the influence of experience, and a complex machine in and of itself. Its characteristic attribute is a huge number of branches, of which the shorter ones (the dendrites) are used to receive