How the Brain Works

The brain sorts among all impressions

The brain is constantly subjected to impressions and impulses from sight, hearing, taste, smell, and feeling. If all this information were to be processed, the brain’s energy conversion would not suffice. To cope with the inflow of information, there are various built-in filters, which define what information passes up to the cerebral cortex and consciousness and which information is stopped along the way. There is a collection of nerve cells in the brain stem, which when activated keeps the cortex alert and “awake” for impressions. Another filtering function is found in the thalamus, which consists of nerve cells deep inside each cerebral hemisphere where the information from our senses passes to advance to the cerebral cortex. The basal ganglia, which is a control system for e.g. movements, but also for mental functions, are also considered to have filter functions. A signal substance that is considered important in filter functions is dopamine.

In the event of damage to the nervous system, the filter systems are affected. They become less efficient and thus more information will reach up to higher brain areas. The person is then disturbed more by sound and light.