An Introduction to Psychology:
The Science of Mind and Behavior

What Does the Cerebral Cortex Do?

The cerebral cortex makes up about 75% of the human brain. It is made up of several layers of cells about 1/8th of an inch thick. This thin collection of cell layers, however, is very tightly folded, somewhat like a crumpled sheet of paper, so that a large amount of it takes up only a small amount of space. Activity in the cerebral cortex is essential for many of the qualities, skills, and abilities that make humans different from all other animals. In fact, if you lost your cerebral cortex, you would lose your self-awareness, your ability to respond with foresight and deliberation to the environment, your ability to relate your past and future to the present, and your ability to speak and understand language. Humans born without much of a cerebral cortex are capable of only the most basic reflexes and emotions (and they tend not to live very long). Humans who have damage to more limited parts of the cerebral cortex show problems with the skills and abilities associated with those parts. Greg, for example, had significant amounts of damage to important parts of his cerebral cortex — damage that made him seem to be a “hollowed-out” version of a human being: he lost much of his former personality, seemed to have little awareness of himself, and tended to treat others interchangeably. These deficits resulted in Greg’s inability to engage in normal human social interactions.

The cerebral cortex (and, in fact, most of the rest of the brain) is divided into two hemispheres (“half-spheres”), one on each side of the head. In the cerebral cortex, activity within each hemisphere is associated with different functions. This localization of different mental and behavioral functions within each hemisphere is referred to as laterality of functioning. For example, in most people, the abilities to use and understand language are associated with activity in the left hemisphere of the cerebral cortex. Because we are highly social animals, these abilities are essential for our survival and well-being. Humans who have lost both their hearing and vision (so that they no longer are able to communicate through normal means) will create very novel ways to express themselves through language. For example, people with Usher’s Syndrome — a disorder in which a person is born deaf and slowly becomes blind during adulthood — typically learn as children to communicate visually with sign language. As their vision disappears during adulthood, many change how they communicate with others: by placing their hands in the hands of others, they learn to sign by touch. As this example clearly shows, we humans are very strongly motivated to communicate. Because our survival depends on communication, it is not surprising that large parts of the cerebral cortex have been set aside for language.

Sensation and Perception
All animals rely very heavily on their senses — sight, hearing, touch, taste, and smell — when adapting themselves to their environments. Sensory information enters the body through sensory receptors in the eyes, ears, skin, bodily joints, tongue, and nose. This information then travels through the PNS, which sends most of it first into the spinal cord, where some processing of the sensory information begins, and then up into the brain, where more complex processing occurs. The most complex processing of sensory information occurs in the cerebral cortex, which is the part of the brain most responsible for our ability to consciously perceive the world around us. Sensation involves the activation of (a) sensory receptors by internal or external stimuli[∂], (b) the PNS leading away from these receptors, and (c) parts of the CNS involved in processing sensory information. Perception, on the other hand, involves the conscious, preconscious, or unconscious recognition (interpretation) of these internal or external stimuli — a recognition that is the end-product of the processing of sensory information during sensation.

The senses of sight, hearing, and touch are each associated primarily with activity in areas of the cerebral cortex referred to as "lobes." Each hemisphere of the cerebral cortex can be separated into four lobes: the frontal, parietal, occipital, and temporal lobes (see Figure 1). The frontal lobes are behind the eyes and forehead; the parietal lobes are on the top (back half) of the head; the occipital lobes are in the back of the head; and the temporal lobes are on the sides of the head around the ears. With respect to sensation and perception, the major functions of each of these lobes have been discovered since the 1800s with a variety of research methods: case studies of people with brain damage, experimental lesioning[∂] of brains in animals, electrical stimulation of brains in animals and humans, and so on. In the rest of this section, you will learn about the results of this research.

Figure 1. The Four Major Lobes in the Cerebral Cortex.
(The picture appears at this link.)

Study Questions

1. The cerebral cortex makes up about what proportion of the human brain?
2. Damage to the cerebral cortex causes what kinds of problems in humans?
3. What is meant by the term "laterality of functioning"?
4. In most people, which side of the cerebral cortex is most closely tied to verbal functions?
5. How does Usher's Syndrome illustrate the importance of verbal communication to humans?
6. How is sensation similar to perception?
7. How does sensation differ from perception?
8. What are the four major lobes of the brain and where are they located?
9. How have the sensory and other functions of the cerebral cortex been discovered by researchers?

What Do the Occipital Lobes Do?

When the occipital lobes in the back of the cortex are electrically stimulated, people generally see colors or flashes of light. This area is referred to as the primary visual cortex because of its association with perceiving visual information. If the visual cortex is damaged, the patient typically develops problems perceiving movement, color, form, and/or parts of the visual field (the totality of what can be seen when a person looks straight ahead). For example, Oliver Sacks (1995) described the case of a 65-year-old artist who was unable to see colors after a car accident had damaged his visual cortex. The man saw the world entirely in shades of black, white, and gray:

It was not just that colors were missing, but that what he did see had a distasteful, “dirty” look, the whites glaring, yet discolored and off-white, the blacks cavernous — everything wrong, unnatural, stained, and impure. ... He saw people’s flesh, his wife’s flesh, his own flesh, as an abhorrent grey; “flesh-colored” now appeared “rat-colored” to him. ... The “wrongness” of everything was disturbing, even disgusting, and applied to every circumstance of daily life. He found foods disgusting due to their greyish, dead appearance and had to close his eyes to eat. ... His own brown dog looked so strange to him now that he even considered getting a dalmation. (pp. 7-8)

Reading a case such as this, we begin to see how important color perception is for us in our everyday lives. In fact, compared to other animals, humans are among the best perceivers of color: we have large areas of our visual cortex devoted to this ability. It is interesting that the damage to this man’s visual cortex also was associated with an increase in his visual acuity — that is, the sharpness of his vision. As he put it, “I can see a worm wriggling a block away” (Sacks, 1995, p. 3).

Information from each side of the visual field crosses over and activates the opposite side of the primary visual cortex (see Figure 2). In other words, the primary visual cortex in the left hemisphere is activated by stimuli in the right visual field, whereas the primary visual cortex in the right hemisphere is activated by stimuli in the left visual field. The reason why visual information crosses over in this way is unknown (and, as you will see below, the same thing is true for other kinds of sensory information, as well as for motor messages[∂] that result in the movement of the skeletal muscles[∂]).

Figure 2. The Crossing Over of Visual Information.

Study Questions

10. Where is the primary visual cortex located?
11. What kinds of information are processed by the primary visual cortex?
12. Which hemisphere of the primary visual cortex is activated by stimuli in the left visual field?
13. Which hemisphere of the primary visual cortex is activated by stimuli in the right visual field?
14. If the occipital lobes were destroyed, what would be the most likely result?

What Do the Parietal Lobes Do?

If surgeons electrically stimulate a strip of tissue running along the anterior (front) part of the parietal lobes (see Figure 3), people typically experience tingling or burning sensations of the skin. This area is referred to as the primary somatosensory cortex, and is associated with perceiving tactile (touch) stimuli. When sensory receptors in the skin are activated, people perceive touching, tingling, tickling, burning, or stinging sensations. As can be seen in Figure 3, the tactile receptors from each part of the body map onto specific areas of the cerebral cortex. For example, tactile receptors from the face map onto a particular part of the cortex — a part immediately adjacent to touch receptors from the thumb. The degree to which a part of the body is sensitive to touch depends upon:

(a) the number of tactile receptors in that part of the body;
(b) the amount of the somatosensory cortex that receives information from that part of the body.

Figure 3 shows that the most sensitive parts of our bodies, such as our hands and lips, take up a large amount of the somatosensory cortex; whereas the least sensitive parts of our bodies, such as our backs, take up a small amount of the somatosensory cortex. [FOR THE FUTURE: 19th-CENTURY PSYCHOPHYSICS STUDIES ON JNDs, ETC. Fechner, 1912/1860; Peirce & Jastrow, 1884; Wozniak, 1999a)

Figure 3. The Primary Somatosensory Cortex and the Parts of the Body From
Which Each Cortical Section Receives Sensory Input.
(The picture appears at this link.)

People who lose a limb (such as an arm or foot) through accidents, disease, or surgery often continue to perceive tactile sensations arising from that missing body part; and sometimes they experience perceptions of severe pain in the missing body part. This phenomenon is referred to as phantom-limb sensations (James, 1887; Ramachandran, ) DISCUSSED IN CLASS (genital-foot example in Figure 3)

Tactile information from each side of the body crosses over and activates the opposite side of the somatosensory cortex. In other words, the somatosensory cortex in the left hemisphere receives tactile sensations from the right side of the body, whereas the somatosensory cortex in the right hemisphere receives tactile sensations from the left side of the body. As with vision, the reason why this information crosses over is unknown.

If the somatosensory cortex is damaged, there typically is only a temporary loss of the sense of touch. The more permanent problem involves difficulties with properly interpreting tactile information. For example, people with damage to the somatosensory cortex often have problems identifying objects by touch, and also may become clumsy because of their difficulties with perceiving the objects they handle.

Areas around the somatosensory cortex are involved in perceiving several other kinds of bodily information. For example, when sensory receptors in the muscles and joints are activated, people sense the positions of these bodily parts and the stretching of limbs. Sometimes, when the somatosensory cortex in the right hemisphere is damaged, people seem not to perceive the left side of their bodies: they act as if the left side of their bodies — and even the left side of their environments — do not exist, a phenomenon referred to as "left-side neglect." For example, people may fail to dress that side of the body, may ignore anything in the environment on that side of the body, or may feel as if parts of the body on that side do not really belong to them. Oliver Sacks (1987) described one such case in a man who showed up at a neurology clinic because of a “lazy” left leg:

He had felt fine all day, and fallen asleep towards evening. When he woke up he felt fine too, until he moved in the bed. Then he found, as he put it, ‘someone’s leg’ in the bed — a severed human leg, a horrible thing! He was stunned, at first, with amazement and disgust — he had never experienced, never imagined, such an incredible thing. He felt the leg gingerly. It seemed perfectly formed, but ‘peculiar’ and cold. ... [H]e threw the damn thing out of the bed. But ... when he threw it out of bed, he somehow came after it — and now it was attached to him. ... He seized it with both hands, with extraordinary violence, and tried to tear it off his body, and, failing, punched it in an access of rage. (pp. 55-56)

Even at this point, the man did not realize that the leg was his own. When asked where his own left leg was, the man answered: “I don’t know. ... I have no idea. It’s disappeared. It’s gone. It’s nowhere to be found” (p. 57). When the somatosensory cortex in the left hemisphere is damaged, on the other hand, the resulting problems seem to be much more specific to the sense of touch. In general, the somatosensory cortex and associated areas of the parietal lobes seem to be important for sensing and orienting our bodies in space.

ANOSOGNOSIA--"nosos" is a Greek word meaning "disease"; a- is a Latin prefix meaning "not" or "lack of": "gnosis" is a Greek word meaning "knowledge. " Thus, the term "anosognosia" is a syndrome in which a person seems unaware that he or she has a disorder. People who receive damage to the right hemisphere of the cerebral cortex sometimes show paralysis of the left side of the body, but seemingly have little or no direct awareness that they are paralyzed. For example, Antonio Damasio (1994), a neurologist, described an anosognosic woman under his care (referred to by her initials, DJ):

Whenever I asked my patient DJ about her left-side paralysis, which was complete, she wouls always begin by saying that her movements were entirely normal, perhaps that they had once been impaired but they no longer were. When I would ask her to move her left arm, she would search around for it and, after looking at the inert limb, ask whether I really wanted "it" to move "by itself." When I would say yes, please, she would then take visual notice of the lack of any motion in the arm, and tell me that "it doesn't seem to do much by itself." As a sign of cooperation, she would offer to have the good hand move the bad arm" "I can move it with my right hand." (p. 63)

This passage shows another troubling feature of her anosognosia. In addition to DJ's lack of awareness of her physical condition, she also expresses no concern when she notices that she can't move her left arm: she experiences no distress over what should be a distressing discovery. According to Damasio (1994), anosognosics in general, show little or no emotion when given the:

news that there was a major stroke, that the risk of further trouble in ... (p. 64)

Anosognosia is associated with damage in .... [SEE PAGES 65-66]

Study Questions

15. Where is the primary somatosensory cortex located?
16. What kinds of information are processed by the primary somatosensory cortex?
17. Which hemisphere of the primary somatosensory cortex is activated by tactile stimuli on the left side of the body?
18. Which hemisphere of the primary somatosensory cortex is activated by tactile stimuli on the right side of the body? On the left side of the body?
19. What determines how sensitive a part of the body will be to tactile sensations?
20. What are phantom-limb sensations?
21. How would you describe the main functions of the somatosensory cortex and related areas in the parietal lobes?
22. What is "left-side neglect" and what is its primary cause?

What Do the Temporal Lobes Do?

If parts of the temporal lobes in the cerebral cortex are electrically stimulateds, a person typically will hear sounds. This area is referred to as the auditory cortex, and is associated with perceiving auditory (sound) information. Unlike vision and touch, information from the sensory receptors in each ear does not cross over. Instead, sensory information received by each ear goes to both the left and right hemispheres. Nevertheless, sensory information from the right ear registers more rapidly in the left hemisphere, whereas sensory information from the left ear registers more rapidly in the right hemisphere.

The auditory hallucinations of people with schizophrenia most often consist of hearing voices of people who are not really there. These hallucinations are associated with abnormal activity in the auditory cortex and language areas linked to the auditory cortex (see below). People with epilepsy[∂] involving abnormal activity in the temporal lobes of the cerebral cortex sometimes hear sounds. For example, Sacks (1987) described such a case in an elderly woman:

One night, ... she dreamt vividly, nostalgically, of her childhood in Ireland, and especially of the songs they danced to and sang. When she woke up, the music was still going, very loud and clear. ‘I must still be dreaming,’ she thought, but this was not so. She got up, roused and puzzled. It was the middle of the night. Someone, she assumed, must have left a radio playing. But why was she the only person to be disturbed by it? She checked every radio she could find — they were all turned off. (p. 132)

She even had difficulty conversing with others because the songs were so loud. There was nothing wrong with her ears, nor was she mentally disordered. It seemed that something was wrong with her brain. When an EEG was taken, Sacks found abnormal amounts of electrical activity in her temporal lobes whenever she heard the music, but not at other times. These seizures had been caused by a small stroke she had suffered the night she began to hear the songs. Over the next several months, her hallucinations became less frequent and eventually disappeared.

What is the Importance of Interactions Among Sensory Areas?

Occipital-Parietal Interactions
RAMACHANDRAN
VISUAL-NAVIGATION PATHWAY (WHERE PATHWAY)

Occipital-Temporal Interactions
Activity in a pathway that leads from the occipital lobes to the temporal lobes is essential for processing visual information in such a way that we are able to recognize objects and places. This visual-recognition pathway, also referred to as the what pathway (Ramachandran & Blakeslee, 1998), is important for our ability to recognize faces. Damage to this pathway in the temporal lobes (especially in the right temporal lobe) may make it impossible for a person to recognize faces, including his or her own face in the mirror. This disorder is called prosopagnosia (also, "visual agnosia" or "face blindness"), and is defined as a severe impairment in the ability to recognize faces, In addition to face blindness, people with prosopagnosia may have trouble with recognizing places (such as a part of town in which they live) and other complex objects (such as the makes and models of cars). Unusual activity in the visual-recognition pathway, such as that caused by a tumor or epilepsy, may cause a person to experience very elaborate visual hallucinations.

CAPGRAS' DELUSION: DISCUSSED IN CLASS

Temporal-Parietal Interactions
Activity at the boundary between the temporal and parietal lobes affects a number of important mental functions. One of the most important involves the use and comprehension of language, especially the comprehension of nouns and verbs. This function involves activity in Wernicke's Area (named after the neurologist, Karl Wernicke, who first described it in 1873), which is located at the boundary between the two lobes in the left hemisphere of most people (see Figure 4). People with damage to language areas in the brain suffer from aphasia, which is a severe impairment in the production and/or comprehension of language. Aphasia is much more than simply having difficulties with speaking due to problems in moving the muscles of the mouth and tongue. Instead, aphasia involves severe deficits in the ability to use language in some or all of its forms. There are different types of aphasia, each of which is characterized by a different set of language difficulties.

Figure 4. Two Language Areas in the Left Hemisphere of the Cerebral Cortex.
(from Kandel, Schwartz, & Jessell, 1995, p. 642)

When Wernicke's Area is damaged, people experience language difficulties referred to as Wernicke's aphasia. Gardner (1974) described such a patient, whom he called "Philip Gorgan." Philip, who was 72 years old when interviewed by Gardner, had suffered a stroke that damaged a part of the left hemisphere that included Wenicke's Area. Philip had no trouble expressing himself in language, such as in speech; but what he said often made little sense. For example, in response to Gardner's question about why he had been brought to the hospital, Philip stated:

Boy, I’m sweating. I’m awful nervous, you know, once in a while I get caught up, I can’t mention the tarripoi, a month ago, quite a little, I’ve done a lot well, I impose a lot, while, on the other hand, you know what I mean, I have to run around, look it over, trebbin and all that sort of stuff. (p. 68)

Philip’s speech involved and explosion of words that was very difficult to interrupt. Just as Gardner was about to ask another question, Philip said:

Oh sure, go ahead, any old think you want. If I could I would. Oh, I’m taking the word the wrong way to say, all of the barbers here whenever they stop you it’s going around and around, if you know what I mean, that is tying and tying for repucer, repuceration, well, we were trying the best that we could while another time it was with the beds over there the same thing. (p. 68)

Philip’s speech sounds almost as if he was suffering from a severe psychosis[∂], but he is not. Damage to Wernicke's Area makes it difficult for him to speak coherently. People suffering from Wernicke’s aphasia tend to have two major language impairments.

Eeh, oh malaty? Eeeh, favility? Abelabla tay kare. Abelabl tay to po stay here. ... Aberdar yeste day. ... and then abedeyes dee, aaah, yes dee, ye ship, yeste day es dalababela. Abla desee, abla detoasy, abla ley e porephee, tee arabek. Abla get sik? (Springer & Deutsch, 1993, p. 151)

In general, people with Wernicke's aphasia seem to confuse the different sounds that make up words — a problem that may result in a sort of “word salad” in which their words are tossed together in no particular order. For example, they might say something such as, “Groceries at the store some go and there went Ron,” when they meant to say, “We went to the store to get some groceries and saw Ron there.” Although many of the correct words are contained in the sentence, they are so jumbled that, without more information, a listener cannot know what is being communicated.

People with Wernicke's aphasia also show anosognosia: they seem to be unaware (completely or to varying degrees) that they are not making sense or are communicating poorly.

Difficulty Finding the Correct Word
People with Wernicke's aphasia often have a reduced ability to name objects, which is called anomia. For example, if you show people with Wernicke’s aphasia a picture of an object, such as a slipper, they may be able to describe what it is for (“it goes on a foot”) but be unable to name it. If you tell them that it is a slipper, they will be able to repeat the word ("yes, it's a slipper, slipper") but, when shown the picture a minute later, again will be unable to name it. It doesn’t matter how often you repeat this procedure: they are unable to retrieve the name of the object. When they can't find the correct word, people with Wernicke's aphasia sometimes produce neologisms (newly coined words or expressions), such as "repuceration" and "tarripoi."

Study Questions

23. In which lobes of the cerebral cortex are sounds initially processed?
24. When schizophrenics claim to hear voices, are they actually hearing voices? (Please explain your answer.)
25. Could the hallucinated voices heard by schizophrenics be so loud that the patients would have trouble hearing what someone was saying to them?
26. What is the name of the disorder in which a person is able to see but is unable to recognize faces?
27. Which area (and which hemisphere) in the brain is damaged in a person who can see but not recognize faces?
28. Does a person who can write but cannot speak have aphasia? Why or why not?
29. What are the main symptoms of Wernicke's aphasia?
30. Which part of the brain is damaged in a person with Wernicke's aphasia?
31. Do people with Wernicke's aphasia have trouble with being understood by others or with understanding other people?
32. How much awareness do people with Wernicke's aphasia have regarding their language impairment?
33. Do people with anomia forget what objects are used for?
34. If you tell people with anomia the name of an object and they repeat the name several times, will they then remember the name the next time they are shown the object?

What Do the Frontal Lobes Do?

The frontal lobes are aptly named because they are located at the front of the cerebral cortex just behind the eyes and forhead. The frontal lobes make up a large part of the cerebral cortex in human brains (about 20% or more). It has been known since the 18oos that the frontal lobes are important for voluntary movements of bodily muscles. But not much more was known about the functions of the frontal lobes for over a century. For one thing, many intellectual functions were observed to remain relatively intact even after extensive damage to the frontal lobes. For example, people who have experienced strokes[∂] causing significant damage to the frontal lobes often continue to receive average to above-average scores on intelligence tests. Furthermore, people who had prefrontal lobotomies — an operation (no longer performed) that destroyed connections between parts of the frontal lobes and the rest of the brain — often functioned adequately in many ways. In summarizing the effects of frontal-lobe damage, Howard Gardner (1974) stated that the “frontal-lobe patient”:

may completely fool the unsuspecting psychologist or the physician, who may conclude on the basis of high scores and appropriate answers that he is dealing with a competent individual. That is because the frontal-lobe patient superficially retains the major cognitive, intellectual, and sensory capacities tapped by psychological tests. His deficiencies inhere [exist] in those very judgmental capacities to plan ahead, to assess the consequences of actions, to evaluate alternatives, to conceive of a situation in multiple ways, to detect subtle social and emotional cues, which are the keynotes of the highest human functions, indeed those which, according to [the Russian neurologist, A. R.] Luria, “make a person human.” (p. 433)

In other words, damage to the frontal lobes results in important, though often subtle, cognitive, emotional, and/or behaviuoral changes that often are reflected in personality changes. It may be difficult for one who doesn't know the patient well to state precisely what is wrong. For those who knew the patient both before and after frontal-lobe injuries, the patient may appear less motivated, more impulsive, and less able to organize his or her thoughts. In this part of Section 2-2, you will learn more about the three major functions of the frontal lobes:

Initiating Movement
There is a strip of cells at the back of the frontal lobes that, when electrically stimulated, produces movements of the skeletal muscles — the muscles attached to the skeleton of the body. This area is referred to as the primary motor cortex, and is associated with moving the skeletal muscles. As can be seen in Figure 5, the movement of each part of the body is controlled by activity in specific areas of the motor cortex. For example, movement of the tongue is controlled by a part of the motor cortex that is located near movement of the lips; and movement of the neck is controlled by a part of the motor cortex that is located near movement of the eyes and eyelids. The degree to which a part of the body is able to be moved in highly complex and coordinated sequences of behaviors is dependent upon the amount of the motor cortex reserved for the movement of that body part. For example, our thumbs and fingers are able to engage in many highly coordinated movements; and, as you can see in Figure 5, a large part of the motor cortex controls movements of the hands and fingers. The muscles on our backs, however, are not capable of performing anything but simple movements; and Figure 5 shows that little of the motor cortex is set aside for moving these muscles.

Figure 5. The Primary Motor Cortex and the Bodily Areas
Affected By Activity in Each Part.
(The picture appears at this link.)

As with vision and touch, the neural pathways controlling movement cross over, which means that movements on the left side of the body are controlled by activity on the right side of the primary motor cortex, whereas movements on the right side of the body are controlled by activity on the left side of the primary motor cortex. Paralysis occurs when any part of the primary motor cortex is damaged. When this occurs, paralysis develops on the side of the body opposite to the damage.

Language Production
The frontal lobes are essential for complex information processing using input from many other areas of the brain. Clinical research suggests that, once sensory information has been received and recognized in the sensory areas of the cortex, the processed information is sent to the frontal lobes, which organizes and processes it further. One example of this is seen in the mental processing that occurs in Broca's Area (see Figure 4). Broca’s area is in the left frontal lobe of most people, and is involved in comprehending and producing language, whether spoken or written. When Broca’s area is damaged, people experience language difficulties called Broca's aphasia (named after the neurologist who first described it in 1861, Paul Broca). People with Broca’s aphasia also typically have paralysis on the right side of the body. This is because Broca’s area is located next to the left motor cortex in most people. Thus, when Broca’s area is damaged, the motor cortex also often receives some damage, thereby producing paralysis on the opposite side of the body (often involving the right arm and hand).

Gardner (1974) described a patient with Broca's aphasia, whom he called "David Ford." David was in his late 30s when interviewed by Gardner, and had been a radio operator in the Coast Guard until he suffered a stroke that put an end to his career. After the stroke, David experienced much difficulty producing written and spoken language. When he was able to produce words, he did so in a halting manner and made many mistakes. These problems are evident in Gardner's description of his initial interview with David soon after he entered the hospital:

I asked Mr. Ford about his work before he entered the hospital.
“I’m a sig. . . no . . . man . . . uh, well, . . . again.” These words were emitted slowly, and with great effort. The sounds were not clearly articulated; each syllable was uttered harshly, explosively, in a throaty voice. With practice, it was possible to understand him, but at first I encountered considerable difficulty in this.
“Let me help you,” I interjected. “You were a signal . . .”
“A sig-nal man . . . right,” Ford completed my phrase triumphantly.
“Were you in the Coast Guard?”
“No, er, yes, yes . . . ship . . . Massachu . . . chusetts . . . Coastguard . . . years.” He raised his hands twice, indicating the number “nineteen.”
“Oh, you were in the Coast Guard for nineteen years.”
“Oh . . . boy . . . right . . .,” he replied.
“Why are you in the hospital, Mr Ford?”
Ford looked at me a bit strangely, as if to say, Isn’t it patently obvious? He pointed to his paralyzed arm and said, “Arm no good,” then to his mouth and said, “Speech . . . can’t say . . . talk, you see.”
“What happened to make you lose your speech?”
“Head, fall, Jesus Christ, me no good, str, str . . . oh Jesus . . . stroke.”
“I see. Could you tell me, Mr. Ford, what you’ve been doing in the hospital?”
“Yes, sure. Me go, er, uh, P.T. none o’cot, speech . . . two times . . . read . . . wr . . . ripe, er, rike, er, write . . . practice . . . get-ting better.”
“And have you been going home on weekends?”
“Why, yes . . . Thursday, er, er, er, no, er, Friday . . . Bar-ba-ra . . . wife . . . and, oh, car . . . drive . . . purnpike . . . you know . . . rest and . . . tee-vee.”
“Are you able to understand everything on television?”
“oh, yes, yes . . . well . . . al-most.” Ford grinned a bit. (pp. 60-61)

It is obvious that David had a great deal of trouble expressing himself in this conversation. Furthermore, unlike people with Wernicke's aphasia, people with Broca’s aphasia realize that they are having difficulty expressing themselves, and often become distressed about this, as did David in the passage quoted above. People suffering from Broca's ’s aphasia tend to have two major language impairments:

Difficulty Comprehending Words
People with Broca's aphasia often have difficulty comprehending "grammatical words" — words other than nouns and verbs that allow us to construct meaningful sentences (Geschwind, 1974; Goodglass & Geschwind, 1976). These include classes of words such as:

People with Broca’s aphasia often omit and seem not to understand ”grammatical words.” Thus, they have great difficulty understanding a sentence such as:“The ball was hit by Zoltran into the left-field bleachers.” The words most likely to be understood by a Broca’s patient would be, “... ball ... hit ... Zoltran ... left-field bleachers.” This is because a person with Broca’s aphasia understands primarily nouns and action verbs. On the other hand, if the sentence had been structured differently so that there were fewer grammatical words, Broca’s patients probably would have little difficulty understanding its meaning. For example, if the sentence had been, “Zoltran hit the ball into the left-field bleachers,” a Broca’s patient probably would have heard something like, ”Tom hit ... ball ... left-field bleachers,” an utterance that is more easily understood than the previous one.

Portions of the brain other than Broca's and Wernicke's Areas are also involved language use and comprehension. In fact, people who have damage only to Broca’s area or only to Wernicke’s area generally do not show fully the difficulties described above. In other words, the full explanation for each of these two aphasias still is not known. In addition, there are other types of aphasia. These other aphasias seem to be associated with damage to other portions of the brain — portions that are not always in the cerebral cortex. Thus, language use and comprehension seems to be associated with activity in many different areas of the brain spread throughout the cortex, limbic system, and brain stem. Because our understanding of language and brain activity is still very primitive, there is a great deal of controversy among researchers concerning the neural explanations of language.

Study Questions

35. The frontal lobes make up about how much of the cerebral cortex?
36. Why had it been so difficult until relatively recently to understand the major functions of the frontal lobes?
37. What are the three major functions of the frontal lobes?
38. Which part of the frontal lobes controls movement of the skeletal muscles?
39. What happens if the primary motor cortex in the right hemisphere is damaged?
40. According to Figure 5, if the part of the motor cortex that controls movements of the eyeball and eyelid is damaged, what other movements might a person have difficulty performing?
41. What does Broca's Area do?
42. How is Broca's aphasia similar to Wernicke's aphasia?
43. How does Broca's aphasia differ from Wernicke's aphasia?
44. How might difficulties in comprehending grammatical words cause the reduced ability of Broca's patients to produce language?
45. If a person has no damage to either Broca's or Wernicke's Areas, can that person still have aphasia? Why or why not?

Working Memory
In order to quickly multiply the following numbers, 4 x 5 x 6, in "your head," you need to do a number of things virtually simultaneously:

• hold the information in mind for at least several seconds;
• give meaning to the information by comparing it to other (relevant) information already stored in memory — memories for numbers, arithmetical symbols, and arithmetical procedures;
• process the information step-by-step according to the arithmetical procedures retrieved from memory;
• monitor and evaluate your progress towards the solution;
• change strategies if you conclude that your progress is inadequate;
• hold in mind the end-product at each step of the procedure while continuing on to the next step;
• and, finally, put the end-products of various steps together at the end to construct the problem's solution.

Although the problem may appear simple, its solution requires you to perform a series of complex mental processes that involve "working memory" (Baddeley & Hitch, 1974). Working memory is a a part of memory that comprises a set of mental structures and processes involved in organizing and integrating sensory and other information. You will learn much more about working memory in Section 4; but for now, let's examine how activity in the frontal lobes is important for the processing of information in working memory.

Working memory, in essence, is essential for a function that we may refer to as problem-solving. Problem-solving ability depends strongly on frontal-lobe activity. In particular, activity in the frontal lobes allows individuals to:

(a) attend to small amounts of information for short periods of time (a function that, as you will learn in Section 4, requires a component of working memory called the "short-term store");
(b) organize and coordinate the set of mental processes that will "work on" this information (a function that, as you will learn in Section 4, is called the "central executive").

The fact that most other areas of the brain send processed information via neural pathways to the frontal lobes is fundamentally important for the problem-solving activities that occur in working memory. In order to understand better the nature of these problem-solving activities, let’s consider an imaginary situation discussed by Kolb and Whishaw (2003):

At the last moment you have invited friends for dinner. Since you have nothing to serve, you must go shopping after you leave work at 5:00 p.m. Before leaving, you prepare a list of items to buy. You are working under a time constraint because you must return home before your guests arrive and you need time to prepare. Since the items you need are not all at the same store, you must make an efficient plan of travel. You also must not be distracted by stores selling items you do not need (such as shoes) or by extended chats with store clerks or friends that you might encounter. (p. 395)

Although such a situation might be somewhat stressful for most of us, we probably would have little trouble completing the necessary tasks successfully. In order to accomplish the goal, we would be able to hold all the necessary information in mind, plan the necessary actions, get back to the tasks after being distracted by various events around us, and so on. People with frontal-lobe damage, on the other hand, would be less able to deal effectively with this situation because they would be unable to problem-solve effectively. Effective problem-solving requires that we:

• Develop several alternative plans to accomplish the goal.
• Compare and contrast these plans in order to evaluate them.
• Choose what seems to be the best plan given the circumstances.
• Implement the plan.
• Ignore irrelevant events (such as a colorful sign in a store window).
• Keep track of already completed tasks.
• Evaluate our progress towards achievement of the ultimate goal.
• Modify the plan when problems are encountered.

Frontal-Lobe Damage
When the frontal lobes are damaged, people become less able to use what they already know to solve problems primarily because of one major cognitive deficit: they are less able to attend long enough to the information contained in a problem needed to solve it. In other words, even when "frontal-lobe patients" begin to work on a problem, irrelevant details and events distract them; and these distractions cause them to quickly lose the essential information from their working memories. Because of this deficit, the behavior of frontal-lobe patients tends to be controlled more by external events than by their internal decisions and internalized knowledge of the world (their short-term and long-term memories; see Section 4).

This is very similar to what happens in preschool children, who also have a great deal of difficulty attending to tasks because their attention constantly is distracted by things going on around them. The similarity of preschool children to frontal-lobe patients when engaged in problem-solving activities is due to the fact that the childrens' frontal lobes are still developing and the patients' frontal lobes are no longer working like those of normal adults. This shows that, without fully functioning frontal lobes, our working memories are severely impaired:

People whose [working] memory is defective become dependent upon environmental cues to determine their behavior. That is, behavior is not under the control of internalized knowledge but is controlled directly by external [events]. One effect of this condition is that people with frontal lobe injuries have difficulty inhibiting behavior directed to external stimuli. (Kolb & Whishaw, 2003, p. 397).

By responding to unimportant and irrelevant environmental events, frontal-lobe patients typically forget what they were trying to do. In fact, we all experience similar problems (to a more limited degree) every day when we are about to do something but then get distracted briefly by some irrelevant event. If the distraction continues long enough or our frontal lobes are not working at optimal levels (perhaps because of fatigue or intoxication), we find that we can’t remember what we were just about to do.

Related to this problem with maintaining important information in working memory is the difficulty that frontal-lobe patients often have with inhibiting maladaptive or socially inappropriate behaviors. In general, people with frontal-lobe damage tend to act impulsively and/or to show highly emotional behaviors. A famous case illustrating this problem is that of Phineas Gage, who, during the late 1840s, was a foreman in charge of a group of men building a railroad. In 1848, a large portion of his left frontal lobe (and, perhaps, part of his right frontal lobe) was destroyed by a metal rod that was driven through his left cheekbone and out the top of his skull by an explosion (see Harlow, 1848, for a description of the accident and the resulting damage). Before the accident, Gage was of normal intelligence, industrious, and very conscientious. After the accident, a complete change in his personality was observed. According to Harlow (1868):

Gage was fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires, at times pertinaciously obstinate, yet capricious and vacillating, devising many plans of future operations, which are no sooner arranged than they are abandoned in turn for others appearing more feasible. A child in his intellectual capacity and manifestations, he has the animal passions of a strong man. Previous to his injury, although untrained in the schools, he possessed a well-balanced mind, and was looked upon by those who knew him as a shrewd, smart businessman, very energetic and persistent in executing all his plans of operation. In this regard his mind was radically changed, so decidedly that his friends and acquaintances said he was 'no longer Gage'.

Thus, it seemed that the damage to Gage's frontal lobes caused him to lose his inhibitions and to act on any impulse or emotion he felt at the moment.

Some people with frontal-lobe damage, however, lose the motivation to engage in much complex behavior. Unlike Phineas Gage, these people become withdrawn, indifferent, and passive. This change to a more apathetic personality was demonstrated in a case study of a 46-year-old salesman whose left frontal lobe was removed after a traffic accident. Although several months after the surgery, he showed above-average intelligence, could move most of his right side easily, demonstrated no aphasia, and had normal memory, he exhibited a major change in personality:

Prior to the accident, the patient had been garrulous [talkative], enjoyed people, had many friends and talked freely. He was active in community affairs, including Little League, church activities, men’s clubs, and so forth. It was stated by one acquaintance that the patient had a true charisma, “whenever he entered a room there was a change in the atmosphere, everything became more animated, happy and friendly.” Following the head injury, he was quiet and remote. He would speak when spoken to and made sensible replies but would then lapse into silence. He made no friends on the ward, spent most of his time sitting alone smoking. He was frequently incontinent of urine, occasionally of stool. He remained unconcerned about either and was frequently found soaking wet, calmly sitting and smoking. ... He was totally unconcerned about his wife and children. Formerly a warm and loving father, he did not seem to care about his family. Eventually the family ceased visiting because of his indifference and unconcern. (Blumer & Benson, 1975; quoted in Kolb & Wishaw, 2003, p. 415)

It seems that whether someone becomes apathetic and withdrawn or active and impulsive depends partly upon which portions of the frontal lobes are damaged. These case studies show, however, that personality, especially how one interacts with others, depends upon the functioning of the frontal lobes.

FROM DAMASIO, 1994: Elliot showed no problems intellectual functioning; and scored in the normal ranges for the scales of the MMPI. His damage was to the ventromedial region of the prefrontal cortex as well as to.... (see pp. 38-39 for description of the damage)

Elliot was able to recount the tragedy of his life with a detachment that was out of step with the magnitude of the events. He was always controlled, always describing scenes as a dispassionate, uninvolved spectator. Nowhere was there a sense of his own suffering.... Elliot was far more mellow in his emotional display now than he had been before his illness. He seemed to approach life on the same neutral note. I never saw a tinge of emotion in my many hours of conversation with him: no sadness, no impatience, no frustration with my incessant and repetitious questioning.... [At home and in other daily situations, Elliot] tended not to display anger, and on the rare occasions when he did, the outburst was swift; in no time he would be his usual new self, calm and without grudges. (pp. 44-45)

Children and Adolescents
As suggested in the description of preschool children above, many of the problems associated with frontal-lobe damage — difficulty with holding an idea in mind, being easily distracted, acting impulsively, being unable to plan actions effectively, being unable to work towards a goal — young children are, in essence if not in fact, “frontal-lobe patients” because it takes several years after birth for the frontal lobes to develop to a point where children are able to regulate well their thoughts, behaviors, and emotions. Children less than five years of age have highly underdeveloped frontal lobes and, thus, they tend to show many of the intellectual and personality characteristics of frontal-lobe patients. They often have trouble holding information in mind for very long (for example, they may forget something you told them five seconds ago) and, because of this, using their internalized knowledge of the world to guide their actions. But there is evidence that the frontal lobes continue to develop into adolescence and, perhaps, into young adulthood (until about 18-20 years of age). Thus, some of the difficulties that teenagers experience in understanding the consequences of their actions, as well as some of their impulsive and risk-taking behaviors, may be the result of underdeveloped frontal lobes.

In general, children less than two years of age are unable to form and use “mental representations” adequately. A mental representation is any mental image of, or thought about, an external event. For example, if you are asked how you put on your jeans and are not allowed to act it out, you will have to go through a series of mental representations before you can answer the question. Mental representations are one important form of “internalized knowledge.” If we want to perform any action in the world, the use of mental representations to plan the action beforehand is essential. For example, when someone asks you for directions, you mentally go through a "cognitive map," which is a mental representation of the layout of the streets and roads in your area. Babies and toddlers under two years show their difficulties with mental representations when they are unable to recognize themselves in a mirror (they have not yet formed a mental representation of their own faces), to use much language (they have not yet formed mental representations of most words), and to engage in “pretend play” (they have not yet formed mental representations of the required roles and objects). Beginning at about two years of age, their frontal lobes have developed sufficiently to allow them to form many more kinds of mental representations. These changes in their frontal lobes are associated with the emergence of all kinds of abilities and skills: they can easily recognize themselves in mirrors, their use of language explodes, and they begin to engage in a great deal of pretend play.

PREFRONTAL LOBOTOMIES; PSYCHOPATHY

Study Questions

46. What is working memory?
47. How is working memory related to problem-solving abilities?
48. In what specific ways does damage to the frontal lobes impair working memory and problem-solving?
49. What does it mean to say that frontal-lobe patients have difficulty using their internalized knowledge?
50. Why are frontal-lobe patients so easily distracted?
51. What personality changes occurred in Phineas Gage after he received frontal-lobe damage?
52. What are the two main types of personality changes seen in people with damage to the frontal lobes?
53. In what ways are young children similar to frontal-lobe patients? Why do they show these similarities?
54. What are mental representations and how are they related to frontal-lobe activity?
55. How are mental representations important for problem-solving?
56. By what age does the ability to mentally represent the world develop sufficiently to allow children to develop complex language skills and to engage in pretend play?
57. With respect to what we know about the development of the frontal lobes, why might teenagers engage in more impulsive and risky behaviors, on average, than adults?