Lobes of the Brain

Learning Objectives

  • Identify the location and function of the lobes of the brain

Forebrain Structures

The two hemispheres of the cerebral cortex are part of the forebrain (Figure 1), which is the largest part of the brain. The forebrain contains the cerebral cortex and a number of other structures that lie beneath the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system (collection of structures). The cerebral cortex, which is the outer surface of the brain, is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory. Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.

An illustration shows the position and size of the forebrain (the largest portion), midbrain (a small central portion), and hindbrain (a portion in the lower back part of the brain).

Figure 1. The brain and its parts can be divided into three main categories: the forebrain, midbrain, and hindbrain.

Lobes of the Brain

The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 2). The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for higher-level cognitive functioning; and Broca’s area, which is essential for language production.

An illustration shows the four lobes of the brain.

Figure 2. The lobes of the brain are shown.

People who suffer damage to Broca’s area have great difficulty producing language of any form. For example, Padma was an electrical engineer who was socially active and a caring, involved mother. About twenty years ago, she was in a car accident and suffered damage to her Broca’s area. She completely lost the ability to speak and form any kind of meaningful language. There is nothing wrong with her mouth or her vocal cords, but she is unable to produce words. She can follow directions but can’t respond verbally, and she can read but no longer write. She can do routine tasks like running to the market to buy milk, but she could not communicate verbally if a situation called for it.

Probably the most famous case of frontal lobe damage is that of a man by the name of Phineas Gage. On September 13, 1848, Gage (age 25) was working as a railroad foreman in Vermont. He and his crew were using an iron rod to tamp explosives down into a blasting hole to remove rock along the railway’s path. Unfortunately, the iron rod created a spark and caused the rod to explode out of the blasting hole, into Gage’s face, and through his skull (Figure 3). Although lying in a pool of his own blood with brain matter emerging from his head, Gage was conscious and able to get up, walk, and speak. But in the months following his accident, people noticed that his personality had changed. Many of his friends described him as no longer being himself. Before the accident, it was said that Gage was a well-mannered, soft-spoken man, but he began to behave in odd and inappropriate ways after the accident. Such changes in personality would be consistent with loss of impulse control—a frontal lobe function.

Beyond the damage to the frontal lobe itself, subsequent investigations into the rod’s path also identified probable damage to pathways between the frontal lobe and other brain structures, including the limbic system. With connections between the planning functions of the frontal lobe and the emotional processes of the limbic system severed, Gage had difficulty controlling his emotional impulses.

However, there is some evidence suggesting that the dramatic changes in Gage’s personality were exaggerated and embellished. Gage’s case occurred in the midst of a 19th century debate over localization—regarding whether certain areas of the brain are associated with particular functions. On the basis of extremely limited information about Gage, the extent of his injury, and his life before and after the accident, scientists tended to find support for their own views, on whichever side of the debate they fell (Macmillan, 1999).

Image (a) is a photograph of Phineas Gage holding a metal rod. Image (b) is an illustration of a skull with a metal rod passing through it from the cheek area to the top of the skull.

Figure 3. (a) Phineas Gage holds the iron rod that penetrated his skull in an 1848 railroad construction accident. (b) Gage’s prefrontal cortex was severely damaged in the left hemisphere. The rod entered Gage’s face on the left side, passed behind his eye, and exited through the top of his skull, before landing about 80 feet away. (credit a: modification of work by Jack and Beverly Wilgus)

Link to learning

Watch this entertaining clip about Phineas Gage to learn more about his accident and injury.

A diagram shows the organization in the somatosensory cortex, with functions for these parts in this proximal sequential order: toes, ankles, knees, hips, trunk, shoulders, elbows, wrists, hands, fingers, thumbs, neck, eyebrows and eyelids, eyeballs, face, lips, jaw, tongue, salivation, chewing, and swallowing.

Figure 4. Spatial relationships in the body are mirrored in the organization of the somatosensory cortex.

The brain’s parietal lobe is located immediately behind the frontal lobe, and is involved in processing information from the body’s senses. It contains the somatosensory cortex, which is essential for processing sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex (Figure 4). For example, the portion of the cortex that processes sensory information from the hand is adjacent to the portion that processes information from the wrist.

An illustration shows the locations of Broca’s and Wernicke’s areas.

Figure 5. Damage to either Broca’s area or Wernicke’s area can result in language deficits. The types of deficits are very different, however, depending on which area is affected.

The temporal lobe is located on the side of the head (temporal means “near the temples”), and is associated with hearing, memory, emotion, and some aspects of language. The auditory cortex, the main area responsible for processing auditory information, is located within the temporal lobe. Wernicke’s area, important for speech comprehension, is also located here. Whereas individuals with damage to Broca’s area have difficulty producing language, those with damage to Wernicke’s area can produce sensible language, but they are unable to understand it (Figure 5).

The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information. The occipital cortex is organized retinotopically, which means there is a close relationship between the position of an object in a person’s visual field and the position of that object’s representation on the cortex. You will learn much more about how visual information is processed in the occipital lobe when you study sensation and perception.

Food for Thought

Consider the following advice from Joseph LeDoux, a professor of  neuroscience and psychology at New York University, as you learn about the specific parts of the brain:

Be suspicious of any statement that says a brain area is a center responsible for some function. The notion of functions being products of brain areas or centers is left over from the days when most evidence about brain function was based on the effects of brain lesions localized to specific areas. Today, we think of functions as products of systems rather than of areas. Neurons in areas contribute because they are part of a system. The amygdala, for example, contributes to threat detection because it is part of a threat detection system. And just because the amygdala contributes to threat detection does not mean that threat detection is the only function to which it contributes. Amygdala neurons, for example, are also components of systems that process the significance of stimuli related to eating, drinking, sex, and addictive drugs.

Glossary

auditory cortex: strip of cortex in the temporal lobe that is responsible for processing auditory information
Broca’s area: region in the left hemisphere that is essential for language production
cerebral cortex: surface of the brain that is associated with our highest mental capabilities
forebrain: largest part of the brain, containing the cerebral cortex, the thalamus, and the limbic system, among other structures
frontal lobe: part of the cerebral cortex involved in reasoning, motor control, emotion, and language; contains motor cortex
motor cortex: strip of cortex involved in planning and coordinating movement
occipital lobe: part of the cerebral cortex associated with visual processing; contains the primary visual cortex
parietal lobe: part of the cerebral cortex involved in processing various sensory and perceptual information; contains the primary somatosensory cortex
prefrontal cortex: area in the frontal lobe responsible for higher-level cognitive functioning

somatosensory cortex: essential for processing sensory information from across the body, such as touch, temperature, and pain
sulcus (plural: sulci): depressions or grooves in the cerebral cortex
temporal lobe: part of cerebral cortex associated with hearing, memory, emotion, and some aspects of language; contains primary auditory cortex
Wernicke’s area: important for speech comprehension