Overview of cerebral function

[Merna]

The cerebrum is divided by a longitudinal fissure into 2 hemispheres, each containing 6 discrete lobes:

Frontal
Parietal
Temporal
Occipital
Insula
Limbic

The frontal, temporal, parietal, and occipital lobes cover the brain’s surface (see figure Lobes of the brain); the insula is hidden under the Sylvian fissure. The limbic lobe (limbic system) is a C-shaped area on the most medial edge of each cerebral hemisphere; it includes some parts of the adjacent lobes.
Although specific functions are attributed to each lobe, most activities require coordination of multiple areas in both hemispheres. For example, although the occipital lobe is essential to visual processing, parts of the parietal, temporal, and frontal lobes on both sides also process complex visual stimuli.
Brain function is extensively lateralized. Visual, tactile, and motor activities of the left side of the body are directed predominantly by the right hemisphere and vice versa. Certain complex functions involve both hemispheres but are directed predominantly by one (cerebral dominance). For example, the left hemisphere is typically dominant for language, and the right is dominant for spatial attention.
The cerebral cortex (see figure Areas of the brain) contains

The primary sensory areas
The primary motor cortex
Multiple association areas, including unimodal and heteromodal association areas

The primary sensory areas receive somesthetic, auditory, visual, and gustatory stimuli from the thalamus, which receives stimuli from specialized sensory organs and peripheral receptors. Olfactory pathways bypass the thalamus and go directly to specialized areas of the cortex. Sensory stimuli are further processed in association areas that relate to one or more senses.
The primary motor cortex generates volitional body movements; motor association areas help plan and execute complex motor activity.
Each unimodal association area is adjacent to its corresponding primary sensory area and processes information from that area at a higher level than the primary sensory area.
Heteromodal association areas are not restricted to any single motor or sensory function but receive convergent information from multiple sensory and motor areas of the brain. Heteromodal association areas in the frontal, temporal, and parietal lobes integrate sensory data, motor feedback, and other information with instinctual and acquired memories. This integration facilitates learning and creates thought, expression, and behavior.