The temporal lobes are on the sides of the cerebral cortex (see Figure 1 in Section 4-3). If a particular area of each temporal lobe is electrically stimulated, a person typically will hear sounds. This area is referred to as the auditory cortex and is associated with the perception of 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 as well as in language areas in the left side of the cerebral cortex (Bentaleb, Beauregard, Liddle, & Stip, 2002). Oliver Sacks (1987) described the case of an elderly woman who experienced unique auditory hallucinations when a small stroke caused abnormal activity in her auditory cortex:

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 stated that she could hear the music, but not at other times. Over the next several months, her hallucinations became less frequent and eventually disappeared, which suggests that the abnormal activity in her temporal lobes had ceased.

Wernicke's Area

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. Most people have language functions associated with activity in the left hemispheres of their cerebral cortex (see Section 3-8). People with damage to language areas suffer from aphasia, which is a severe impairment in the production and/or comprehension of language. There are different types of aphasia, each of which is characterized by a different set of language difficulties caused by abnormal activity — or loss of activity when an area is completely destroyed — in various areas of (typically) the left side of the cerebral cortex. 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 and/or comprehend language in some or all of its forms (that is, in writing, speaking, the use of sign language, etc.).

Figure 1. Two language areas in the left hemisphere of the cerebral cortex
(from Kandel, Schwartz, & Jessell, 1995, p. 642)

One of the language areas in the left hemisphere is called Wernicke's Area, named after the neurologist, Karl Wernicke, who first described it in 1873. It is located at the border between the temporal and parietal lobes (see Figure 1; we'll talk about Broca's Area in Section 4-7). When Wernicke's Area is damaged and severe language impairments occur, people are said to have Wernicke's aphasia. Gardner (1974) described an elderly patient with Wernicke's aphasia, whom he called "Philip Gorgan." Philip suffered a stroke in Wenicke's Area and, while he had no trouble expressing himself in language, such as in speech, 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 an 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 was not. Damage to Wernicke's Area made it difficult for him to speak coherently. People suffering from Wernicke’s aphasia tend to have two major language impairments:

• difficulty comprehending words, especially nouns and verbs;
• difficulty finding the correct noun when naming objects.

Difficulty comprehending words. Although people with Wernicke’s aphasia tend to have little trouble speaking or writing, what they say or write makes little sense; and they also have difficulty making sense of what others say to them. In severe cases, they may become incoherent but seemingly are unaware that their language is severely impaired. Thus, people with Wernicke's aphasia show anosognosia (see Section 4-5): they seem to be unaware, to varying degrees, that they are making little or no sense. For example, in response to the question, “how did you get sick?”, a patient with Wernicke's aphasia answered:

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)

This patient seemed to be unaware that he was making up most of his words.

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 the person is trying to communicate.

Difficulty finding the correct word. The impairments described in the previous two paragraphs probably are due to a language difficulty experienced by people with damage to Wernicke's Area called anomia — a reduced ability to name objects. If you show people with Wernicke’s aphasia a picture of a slipper, for example, 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"), which suggests that they have the word stored in memory 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 recall 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,""tarripoi," "favility," and "abelabla" in the quotations above.

Study Questions for Section 4-6

1. In which lobes of the cerebral cortex are sounds initially processed?
2. When schizophrenics hear voices, are they actually hearing voices? (Please explain your answer.)
3. Does a person who can write but cannot speak have aphasia? Why or why not?
4. What are the main symptoms of Wernicke's aphasia?
5. Which part of the brain is damaged in a person with Wernicke's aphasia?
6. Do people with Wernicke's aphasia have trouble with being understood by others or with understanding other people (or both)?
7. How much awareness do people with Wernicke's aphasia have regarding their language impairment?
8. Do people with anomia forget what objects are used for?
9. 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? Why or why not?

Go to Quiz 4-6 questions

Go to Readings Section 4-7