The cerebrum is the largest part of the brain. It is in the front part of the brain. It contains about 15 billion cells, and is the latest brain structure to have evolved.
The cerebrum takes in data from sight and other sense organs, and 'makes sense' of it (interprets it). It controls consciousness and action (voluntary muscular activity). It plans, thinks, judges, and organises speech and information. These are the so-called 'higher mental functions'.
The cerebrum is divided into two cerebral hemispheres. These two cerebral hemispheres are connected by three bands of nerve fibres, or commissures, which connect the two halves. The outer layers of the cerebrum are made up of the grey matter, and is called the cerebral cortex. The inner layers are made up of the white matter (nerve fibres), and the basal ganglia.
In the cerebrum, there are specific regions for each kind of stimulus and its response. For example, occipital lobe is the region for visual reception, temporal lobe for auditory reception, and parietal lobe for touch, smell, temperature and conscious association. The frontal lobe takes action, based on sensory input and other factors.