FUNCTION OF THE CEREBRAL LOBES
Topic: Nervous System A&P
Next Unit: Other Structures of the Brain
12 minute read
The concept of dividing the cerebrum into "lobes" is used to divide the brain into rough areas based on general function. Each lobe consists of an area of superficial cerebral cortex (gray matter) and its underlying cerebral white matter. The four lobes are the
- temporal and
- occipital lobes.
There are two of each, one for both the left and right sides of the body.
The frontal lobes lie immediately behind the forehead and include areas that regulate:
- personality, and
- voluntary movement.
The frontal lobes are located at the front of each cerebral hemisphere and are separated from the parietal lobes posteriorly by a space between the tissues called the central sulcus, and from the temporal lobes laterally by a deep fold called the lateral sulcus.
The precentral gyrus forms the posterior aspect of the frontal lobes and contains the primary motor cortex, which is responsible for controlling voluntary movements of specific body parts.
The more anterior segments of the frontal lobes are associated with:
- short-term memory tasks,
- planning, and
- motivation due to their dopamine-sensitive neurons.
The frontal cortex also contains "Broca's area" which are neurons that control the muscles necessary to produce speech.
The parietal lobes of the brain lie posterior and inferior to the frontal lobes. Their neurons focus on the reception and correlation of sensory stimuli. The parietal lobes integrate sensory information from the various sensations.
Proprioception (body position), mechanoreception (sense of touch), and nociception (pain) are some of the less commonly known senses. The parietal lobes also sense taste (the smell is at the frontal lobe).
This lobe is heavily connected to the thalamus, which is the main relay for all sensory information. The parietal lobes are also crucial for understanding written and spoken language.
Damage to the LEFT parietal lobe can disrupt a person's ability to understand spoken or written language.
Damage to EITHER parietal lobe can cause deficits in visual-spatial awareness--ability to find their way around.
The parietal lobes are separated
- from the frontal lobes by the central sulcus,
- from the occipital lobes by the parieto-occipital sulcus, and
- from the temporal lobes by the lateral sulcus.
The temporal lobes are located laterally on either side of the brain. They are known for their role in the
- formation and recall of memories; are
- critical in the association of emotions; and create the ability to
- recognize, decode, and produce language (in close association with the parietal lobes).
As with the other lobes, there are specific areas allocated to each of the above functions.
HIPPOCAMPUS: an inferomedial area primarily responsible for the formation of new memories.
WERNEKIE'S AREA: the "speech recognition area" of the brain, generally located on the side opposite the dominant hand, at the border of the temporal and parietal lobes. This holds the neurons required to understand and recognize speech.
The occipital lobes of the brain are the most posterior portion of the cerebrum, separated
- from the parietal lobes anteriorly by the parieto-occipital sulcus and
- connected directly to the temporal lobes laterally. T
The occipital lobes are divided into several different visual areas, each which have unique functions:
The primary visual cortex is the main processing center in the brain for raw visual input. Specifically, the occipital lobes process the information sent to them from the thalamus, after the thalamus receives input from the retinas. Once at the occipital lobes, the raw data is turned into "images," which are then sent to the temporal and parietal lobes. There the images are recognized, stored, and reacted to.
NOTE: For each of the senses, there is a receptive area, e.g., the visual cortex in the occipital lobe, the auditory cortex in the temporal lobe, etc., and an associative area in the respective lobe, where the data/info is interpreted and put into perspective for applying to moment-to-moment life. For purposes of illustration, a person with damage to the associative visual cortex but not to the primary cortex would be able to see a comb with excellent acuity--maybe even announce its name, "comb," but be unable to know what to do with it or how it works.
The occipital lobes can be divided into the ventral stream and the dorsal stream.
- The ventral stream allows for the processing of object recognition--"the WHAT pathway"; and
- the dorsal stream allows for the ability to recognize the position of the object in 3D space and the understanding of the situation the object being viewed is in--"the HOW pathway."