Cognition is the processing of information for the purpose of adapting an individual to its environment. Human cognition consists of five primary domains: memory, attention, language, orientation and perception. Each of these domains is localized within cortical regions of the brain. These cortical regions contribute information and activation to the hippocampus, which is responsible for short term or working memory.
Perception occupies the greatest percentage of the human brain. The occipital, parietal and temporal lobes are responsible for sight, touch and hearing, respectively. The parietal lobe is also responsible for maintaining locations of objects using data from the visual and auditory cortices. This is essential to orientation, although a number of sub-cortical structures also contribute to awareness of one own's position.
The temporal lobes are also active during sequenced events. Thus they are the location of language function and musical talent. In most individuals these particular functions of the temporal lobes are lateralized.
Attention is a more elusive function of the brain, not easily localized. In a sense every level of processing contributes to attention. The brain stem and some sub-cortical nuclei affect attention by altering the physiology of the body. If the heart rate is increased, more blood will enter the brain and improve its capabilities. Many neurons from the brain stem penetrate far into the cortex and excite or inhibit other processes. Tracing these individual pathways is time consuming and often of limited value.
Another contributor to attention in humans is the frontal lobe. It is interconnected with all parts of the brain in fairly regular patterns, allowing events in different modalities to be coordinated over time. The pre-frontal cortex is a further abstraction of this function, and is responsible for long-term planning and problem-solving. There have also been studies implicating these areas in affective mood disorders like depression.
Overall, the human brain is a well-orchestrated symphony of lower level processes cooperating to perform tasks essential to survival and success. Each domain of cognition is important to the overall proccess, and conditions that deprive a person of one or more function often destroy the individual. Such is the case with Alzheimer's Disease, autism, stroke and many others.
One must also consider the interaction of multiple cognitive entities within a society or culture to fully understand what it is to be human.