Lobes of the Brain

Lobes of the Brain

The cerebral hemispheres have distinct fissures, which divide the brain into lobes. Each hemisphere has 4 lobes: Frontal, Temporal, Parietal, and Occipital. Each lobe may be divided, once again, into areas that serve very specific functions. It is important to understand that each lobe of the brain does not function alone. These are very complex relationships between the lobes of the brain and between the right and left hemispheres.

Frontal Lobe

The front part of the brain, involved in planning, judgement, reasoning, impulse control, organizing, problem solving, selective attention, personality and a variety of “higher cognitive functions”, including behaviour and emotions.

– The Prefrontal Cortex (front of the Frontal Lobe) is important to personality

– The posterior (back) of the Frontal Lobe serves to modify movements

Both lobes grow measurably between age10 and 12 (with girls’ growth spurt generally coming a little earlier than boys), and then shrink in the twenties as extraneous branches and pruned back into efficient, well-organised circuitry.  

Temporal Lobe

It may be considered that there are two temporal lobes, as one is located about ear-level in each hemisphere of the brain. It contains the primary auditory cortex and part of wernicke’s area. They allow a person to distinguish between different smells and sounds. They also help with new information and are believed responsible for short term memory. Medial parts of the temporal lobe are involved in aspects of memory and learning.

– Right Hemisphere lobe : mainly involved in visual memory (memory for pictures, faces)

– Left Hemisphere lobe : mainly involved in verbal memory (memory for words, names)

These area reach their gray matter peak about age 16, followed by a decade of pruning.

Parietal Lobe

It is associated with integrating sensory information, contains the spatial orientation system, and is involved in the comprehension of language. It maintains two slightly different functions depending on the right or left side of the area. Damage to the right side of parietal lobe can cause visual-spatial difficulties (the patient may have difficulty finding their way around new or even familiar places). Damage to the left side of the parietal lobe may disrupt a patient’s ability to understand spoken and/or written language.

• Primary somatosensory cortex

It is concerned with processing of proprioceptive and tactile stimuli

• Parietal Cortex

It controls aspects of spatial orientation and directing attention

Parietal lobe reach its Gray Matter peak at ages 10 (girls) and 12 (boys) before being pruned. These areas are immature until about the age 16.

• Wernicke’s Area

It is located partially in the parietal lobe (left hemisphere of 90% people). It is involved in recalling, recognizing, and interpreting words and other sounds in the process of using language. Damage to Wernicke’s Area affect a persons ability to string together a coherent sentence or even the loss of the ability to understand language.

Studies suggest the brains ability to link letter combinations with sound may not be fully developed until age 11.   

Occipital Lobe

A region in the back of the brain which processes visual sensations and information (images, shapes, colors). The Visual cortex resides here, and it where reading is made possible.

How our brains process eyesight ?

Each hemisphere of the brain interacts primarily with one half of the body, but for reasons that are unclear, the connections are crossed: the left side of the brain interacts with the right side of the body, and viceversa. Motor connections from the brain to the spinal cord, and the sensory connections from spinal cord the brain, both cross the the midline at brainstem levels. Visual input follows a more complex rule: the optic nerves from the two eyes come together at a point called the optic chiasm, and half of the fibers from each nerve split off to join the other. The result is that connections from the left half of the retina, in both eyes, go to the left side of the brain, whereas connections from the right half of the retina go to the right side of the brain. Because each half of the retina receives light coming from the opposite half of the visual field, the functional consequence is that visual input from the left side of the world goes to the right side of the brain, and vice versa. Thus, the right side of the brain receives somatosensory input from the left side of the body, and visual input from the left side of the visual field – an arrangement that presumably is helpful for visuomotor coordination.