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1 Prepared by Grant McLaren, Department of Psychology, Edinboro University of Pennsylvania FOUNDATIONS OF BEHAVIORAL NEUROSCIENCE 9 TH EDITION This multimedia product and its contents are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network, preparation of any derivative work, including the extraction, in whole or in part, of any images, any rental, lease or lending of the program Copyright © 2014 Pearson Education, Inc. All Rights Reserved

2 Chapter 13 Human Communication Copyright © 2014 Pearson Education, Inc. All Rights Reserved

3 Speech Production and Comprehension: Brain Mechanisms Lateralization Speech Production Speech Comprehension Aphasia in Deaf People Prosody: Rhythm, Tone, and Emphasis in Speech Recognition of People’s Voices Stuttering

4 Copyright © 2014 Pearson Education, Inc. All Rights Reserved Disorders of Reading and Writing Relation to Aphasia Pure Alexia Toward an Understanding of Reading Developmental Dyslexias Toward an Understanding of Writing

5 Human Communication Learning Objectives 1. Describe the use of subjects with brain damage in the study of language and explain the concept of lateralization. 2. Describe Broca's aphasia and the three major speech deficits that result from damage to Broca's area: agrammatism, anomia, and articulation difficulties. 3. Describe the symptoms of Wernicke's aphasia, pure word deafness, and transcortical sensory aphasia and explain how they are related. 4. Discuss the brain mechanisms that underlie our ability to understand the meanings of words and to express our own thoughts and perceptions in words. 5. Describe the symptoms of conduction aphasia and anomic aphasia and the brain damage that produces them. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

6 Human Communication Learning Objectives 6.Discuss research on aphasia in deaf people. 7Discuss research on the brain mechanisms of prosody—the use of rhythm and emphasis in speech—and stuttering. 8Describe pure alexia and explain why this disorder is caused by damage to two specific parts of the brain. 9.Describe whole-word and phonetic reading and discuss three acquired dyslexias: surface dyslexia, phonological dyslexia, and direct dyslexia. 10.Explain the relationship between speaking and writing and describe the symptoms of phonological dysgraphia, orthographic dysgraphia, and semantic (direct) dysgraphia. 11.Describe research on the neurological basis of developmental dyslexias. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

7 Speech Production and Comprehension: Brain Mechanisms Our knowledge of the physiology of language has been obtained primarily by observing the effects of brain lesions on people’s verbal behavior. aphasia Difficulty in producing or comprehending speech not produced by deafness or a simple motor deficit; caused by brain damage. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

8 Speech Production and Comprehension: Brain Mechanisms Lateralization Verbal behavior is a lateralized function; most language disturbances occur after damage to the left side of the brain, whether people are left-handed or right-handed. Right-hemisphere speech dominance is seen in only 4 percent of right-handed people, in 15 percent of ambidextrous people, and in 27 percent of left-handed people. The left hemisphere is dominant for speech in 90 percent of the population. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

9 Speech Production and Comprehension: Brain Mechanisms Speech Production Damage to a region of the inferior left frontal lobe (Broca’s area) disrupts the ability to speak: It causes Broca’s aphasia. This disorder is characterized by slow, laborious, and nonfluent speech. When trying to talk with patients who have Broca’s aphasia, most people find it hard to resist supplying the words the patients are obviously groping for. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

10 Speech Production and Comprehension: Brain Mechanisms Speech Production Although they often mispronounce words, the ones they manage to come out with are usually meaningful. The posterior part of the cerebral hemispheres has something to say, but the damage to the frontal lobe makes it difficult for the patients to express these thoughts. Broca’s aphasia A form of aphasia characterized by agrammatism, anomia, and extreme difficulty in speech articulation. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

11 Speech Production and Comprehension: Brain Mechanisms Speech Production function word A preposition, article, or other word that conveys little of the meaning of a sentence but is important in specifying its grammatical structure. content word A noun, verb, adjective, or adverb that conveys meaning. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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13 Speech Production and Comprehension: Brain Mechanisms Speech Production People with Broca’s aphasia can comprehend speech much better than they can produce it. In fact, some observers have said that their comprehension is unimpaired, but as we will see, this is not quite true. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

14 Speech Production and Comprehension: Brain Mechanisms Speech Production Broca (1861) suggested that this form of aphasia is produced by a lesion of the frontal association cortex, just anterior to the face region of the primary motor cortex. Subsequent research proved him to be essentially correct, and we now call the region Broca’s area. (See Figure 13.2.) Broca’s area A region of frontal cortex, located just rostral to the base of the left primary motor cortex, that is necessary for normal speech production. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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16 Speech Production and Comprehension: Brain Mechanisms Speech Production agrammatism One of the usual symptoms of Broca's aphasia; a difficulty in comprehending or properly employing grammatical devices, such as verb endings and word order. anomia Difficulty in finding (remembering) the appropriate word to describe an object, action, or attribute; one of the symptoms of aphasia. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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18 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Comprehension of speech obviously begins in the auditory system, which detects and analyzes sounds. But recognizing words is one thing; comprehending them— understanding their meaning—is another. Wernicke’s area A region of auditory association cortex on the left temporal lobe of humans, which is important in the comprehension of words and the production of meaningful speech. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

19 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Recognizing a spoken word is a complex perceptual task that relies on memories of sequences of sounds. This task appears to be accomplished by neural circuits in the superior temporal gyrus of the left hemisphere, a region that has come to be known as Wernicke’s area. (Refer to Figure 13.2.) Wernicke’s aphasia A form of aphasia characterized by poor speech comprehension and fluent but meaningless speech. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

20 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Description The primary characteristics of Wernicke’s aphasia are poor speech comprehension and production of meaningless speech. Unlike Broca’s aphasia, Wernicke’s aphasia is fluent and unlabored; the person does not strain to articulate words and does not appear to be searching for them. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

21 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Because the superior temporal gyrus is a region of auditory association cortex and because a comprehension deficit is so prominent in Wernicke’s aphasia, this disorder has been characterized as a receptive aphasia. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

22 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis The abilities that are disrupted include recognition of spoken words, comprehension of the meaning of words, and the ability to convert thoughts into words. Let us consider each of these abilities in turn. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

23 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis pure word deafness The ability to hear, to speak, and (usually) to read and write without being able to comprehend the meaning of speech; caused by damage to Wernicke’s area or disruption of auditory input to this region. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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25 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Sharp, Scott, and Wise (2004) found that deficits in speech comprehension were produced by lesions of the superior temporal lobe that damaged the region that is activated when people hear intelligible speech. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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27 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Figure 13.5 shows a computer-generated depiction of the overlap of lesions of patients with brain damage that interfered with speech perception. Compare the regions of greatest overlap, shown in yellow and green, in Figure 13.5 with the region shown in Figure 13.4. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

28 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Apparently, two types of brain injury can cause pure word deafness: disruption of auditory input to the superior temporal cortex or damage to the superior temporal cortex itself (Poeppel, 2001; Stefanatos, Gershkoff, and Madigan, 2005). Either type of damage disturbs the analysis of the sounds of words and hence prevents people from recognizing other people’s speech. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

29 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Our brains contain circuits of mirror neurons—neurons activated either when we perform an action or see another person performing particular grasping, holding, or manipulating movements or when we perform these movements ourselves (Gallese et al., 1996; Rizzolatti et al. 2001). Feedback from these neurons may help us to understand the intent of the actions of others. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

30 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis Several investigators have suggested that feedback from subvocal articulation (very slight movements of the muscles involved in speech that do not actually cause obvious movement) facilitate speech recognition. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

31 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Wernicke’s Aphasia: Analysis As Figure 13.6 shows, in all three conditions, regions of the brain involved with lip movements (green) and tongue movements (red) were activated. (See Figure 13.6.) Thus, speaking, watching other people speak, thinking about speaking, and listening to speech sounds all activate brain regions involved in language, which suggests that circuits of mirror neurons play a role in speech comprehension. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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33 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Comprehension: Transcortical Sensory Aphasia: Failure to comprehend the meaning of words and the inability to express thoughts in meaningful speech—appear to be produced by damage that extends beyond Wernicke’s area into the region that surrounds the posterior part of the lateral fissure, near the junction of the temporal, occipital, and parietal lobes. For want of a better term, I will refer to this region as the posterior language area. (See Figure 13.7. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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35 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Comprehension: Transcortical Sensory Aphasia: Damage to the posterior language area alone, which isolates Wernicke’s area from the rest of the posterior language area, produces a disorder known as transcortical sensory aphasia. (See Figure 13.7.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

36 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Comprehension: Transcortical Sensory Aphasia: transcortical sensory aphasia A speech disorder in which a person has difficulty comprehending speech and producing meaningful spontaneous speech but can repeat speech; caused by damage to the region of the brain posterior to Wernicke's area. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

37 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Comprehension: Transcortical Sensory Aphasia: The difference between transcortical sensory aphasia and Wernicke’s aphasia is that patients with transcortical sensory aphasia can repeat what other people say to them; therefore, they can recognize words. However, they cannot comprehend the meaning of what they hear and repeat; nor can they produce meaningful speech of their own. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

38 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension What is Meaning? Wernicke’s area is involved in the analysis of speech sounds and thus in the recognition of words. Damage to the posterior language area does not disrupt people’s ability to recognize words, but it does disrupt their ability to understand words or to produce meaningful speech of their own. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

39 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension What is Meaning? Presumably, Wernicke’s area is connected—through the posterior language area—with the neural circuits that contain these memories. (See Figure 13.8.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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41 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension What is Meaning? Functional imaging studies confirm these observations. Nichelli et al. (1995) found that judging the moral of Aesop’s fables (as opposed to judging more superficial aspects of the stories) activated regions of the right hemisphere. Sotillo et al. (2005) found that a task that required comprehension of metaphors such as “green lung of the city” (that is, a park) activated the right superior temporal cortex. (See Figure 13.9.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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43 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Repetition: Conduction Aphasia People with transcortical sensory aphasia can repeat what they hear which suggests that there is a direct connection between Wernicke’s area and Broca’s area—and there is: the arcuate fasciculus (“arch-shaped bundle”). arcuate fasciculus A bundle of axons that connects Wernicke's area with Broca's area; damage causes conduction aphasia. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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45 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Repetition: Conduction Aphasia conduction aphasia An aphasia characterized by inability to repeat words that are heard but the ability to speak normally and comprehend the speech of others. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

46 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Repetition: Conduction Aphasia The symptoms that are seen in transcortical sensory aphasia and conduction aphasia lead to the conclusion that there are pathways connecting the speech mechanisms of the temporal lobe with those of the frontal lobe. The direct pathway through the arcuate fasciculus simply conveys speech sounds from Wernicke’s area to Broca’s area. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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48 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Repetition: Conduction Aphasia The anterior segment connects Broca’s area with the inferior parietal cortex, and the posterior segment connects Wernicke’s area with the inferior parietal cortex. Damage to the direct pathway would be expected to produce conduction aphasia, whereas damage to the indirect pathway would be expected to spare the ability to repeat speech but would impair comprehension. (See Figure 13.12.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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50 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Memory of Words: Anomic Aphasia circumlocution A strategy by which people with anomia find alternative ways to say something when they are unable to think of the most appropriate word. Anomic aphasia is different from Wernicke’s aphasia. People with anomic aphasia can understand what other people say, and what they say makes perfect sense, even if they often choose roundabout ways to say it. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

51 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Memory of Words: Anomic Aphasia Several functional imaging studies have confirmed the importance of Broca’s area and the region surrounding it in the production of verbs. For example, Hauk, Johnsrued, and Pulvermüller (2004) had subjects read verbs that related to movements of different parts of the body. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

52 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Memory of Words: Anomic Aphasia For example, bite, slap, and kick involve movements of the face, arm, and leg, respectively. The investigators found that when the subjects read a verb, they saw activation in the regions of the motor cortex that controlled the relevant part of the body. (See Figure 13.13.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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54 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Aphasia in Deaf People Mirror neurons become active when we see or perform particular grasping, holding, or manipulating movements. Some of these neurons are found in Broca’s area. Presumably, these neurons play an important role in learning to mimic another people’s hand movements. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

55 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Aphasia in Deaf People Indeed, they might have been involved in the development of hand gestures used for communication in our ancestors, and they undoubtedly are used by deaf people when they communicate by sign language. A functional imaging study by Iacoboni et al. (1999) found that Broca’s area was activated when people observed and imitated finger movements. (See Figure 13.14.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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57 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Aphasia in Deaf People Several studies have found a linkage between speech and hand movements, which supports the suggestion that the spoken language of present-day humans evolved from hand gestures. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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59 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Aphasia in Deaf People As you might imagine, when a hearing person is asked to look at a pair of drawings and say whether the names of the items they show rhyme, functional imaging shows increased activation in the region of Broca’s area because the person “says” the two words subvocally. And if we ask deaf people who are able to talk to perform this task, the same region is activated (MacSweeney et al., 2008b). (See Figure 13.16.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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61 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Prosody: Rhythm, Tone, and Emphasis in Speech Our speech has a regular rhythm and cadence; we give some words stress (that is, we pronounce them louder), and we vary the pitch of our voice to indicate phrasing and to distinguish between assertions and questions. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

62 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Prosody: Rhythm, Tone, and Emphasis in Speech In addition, we can impart information about our emotional state through the rhythm, emphasis, and tone of our speech. These rhythmic, emphatic, and melodic aspects of speech are referred to as prosody. prosody The use of changes in intonation and emphasis to convey meaning in speech besides that specified by the particular words; an important means of communication of emotion. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

63 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Prosody: Rhythm, Tone, and Emphasis in Speech Evidence from studies of normal people and patients with brain lesions suggests that prosody is a special function of the right hemisphere. This function is undoubtedly related to the more general role of this hemisphere in musical skills and the expression and recognition of emotions: Production of prosody is rather like singing, and prosody often serves as a vehicle for conveying emotion. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

64 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Prosody: Rhythm, Tone, and Emphasis in Speech As you can see in Figure 13.17, the meaningful components of speech primarily activated the left hemisphere (blue and green regions), whereas the prosodic components primarily activated the right hemisphere (orange and yellow regions). (See Figure 13.17.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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66 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Recognition of People’s Voices People learn at an early age to recognize the voices of particular individuals. Even newborn infants can recognize the voices of their parents, which they apparently learned while they were still in their mother’s uterus (Ockleford et al., 1988). Some people with localized brain damage have great difficulty recognizing voices—a disorder known as phonagnosia. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

67 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Recognition of People’s Voices Most cases of phonagnosia are caused by brain damage. Recognition of a particular voice is independent of the recognition of words and their meanings. Some people have lost the ability to understand words but can still recognize voices, while others display the opposite deficits (Belin, Fecteau, and Bédard, 2004). Copyright © 2014 Pearson Education, Inc. All Rights Reserved

68 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Recognition of People’s Voices Functional imaging studies have implicated the right anterior superior temporal cortex in voice recognition. For example, von Kriegstein et al. (2003) found that this region was activated by a task that required subjects to recognize particular voices but not particular words. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

69 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Stuttering Stuttering is a speech disorder characterized by frequent pauses, prolongations of sounds, or repetitions of sounds, syllables, or words that disrupt the normal flow of speech. Stuttering, which appears to be influenced by genetic factors, affects approximately 1 percent of the population and is three times more prevalent in men than in women (Brown et al., 2005; Fisher, 2010). Copyright © 2014 Pearson Education, Inc. All Rights Reserved

70 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Stuttering Stuttering is not a result of abnormalities in the neural circuits that contain the motor programs for speech. For example, stuttering is reduced or eliminated when a person reads aloud with another speaker, sings, or reads in cadence with a rhythmic stimulus. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

71 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Stuttering Neumann et al. (2005) provide further evidence that the apparently abnormal auditory feedback in stutterers is reflected in decreased activation of their temporal cortex. The authors used fMRI to measure the regional brain activation of stutterers reading sentences aloud during two sessions, one before and one after a successful twelve-week course of fluency shaping therapy. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

72 Speech Production and Comprehension: Brain Mechanisms Speech Comprehension Stuttering Figure 13.18 shows that after the therapy, the activation of the temporal lobe—a region that both Brown et al. (2005) found to show decreased activation—was increased. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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75 Disorders of Reading and Writing Pure Alexia Dejerine (1892) described a remarkable syndrome, which we now call pure alexia, or sometimes pure word blindness or alexia without agraphia. His patient had a lesion in the visual cortex of the left occipital lobe and the posterior end of the corpus callosum. The patient could still write, although he had lost the ability to read. pure alexia Loss of the ability to read without loss of the ability to write; produced by brain damage. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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77 Disorders of Reading and Writing Pure Alexia The flow of visual information for a person with this brain damage enables that person to read words aloud. Information from the left side of the visual field is transmitted to the right striate cortex (primary visual cortex) and then to regions of right visual association cortex. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

78 Disorders of Reading and Writing Pure Alexia From there, the information crosses the posterior corpus callosum and is transmitted to a region of the left visual association cortex known as the visual word-form area VWFA), where it is analyzed further. The information is then transmitted to speech mechanisms located in the left frontal lobe. Thus, the person can read the words aloud. (See Figure 13.20a.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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80 Disorders of Reading and Writing Pure Alexia The second diagram shows Dejerine’s patient. Notice how the additional lesion of the corpus callosum prevents visual information concerning written text from reaching the VWFA in the left hemisphere. Because this brain region is essential for the ability to recognize words, the patient cannot read. (See Figure 13.20b.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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82 Disorders of Reading and Writing Pure Alexia Mao-Draayer and Panitch (2004) reported the case of a man with multiple sclerosis who displayed the symptoms of pure alexia after sustaining a lesion that damaged both the subcortical white matter of the left occipital lobe and the posterior corpus callosum. As you can see in Figure 13.21, the lesions are in precisely the locations that Dejerine predicted would cause this syndrome, except that the white matter that serves the left primary visual cortex is damaged, not the cortex itself. (See Figure 13.21.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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84 Disorders of Reading and Writing Toward an Understanding of Reading Reading involves at least two different processes: direct recognition of the word as a whole and sounding it out letter by letter. whole-word reading Reading by recognizing a word as a whole; “sight reading.” phonetic reading Reading by decoding the phonetic significance of letter strings; “sound reading.” Copyright © 2014 Pearson Education, Inc. All Rights Reserved

85 Disorders of Reading and Writing Toward an Understanding of Reading Figure 13.22 illustrates some elements of the reading processes. The diagram is an oversimplification of a very complex process, but it helps to organize some of the facts that investigators have obtained. If we see an unfamiliar word or a pronounceable nonword, we must try to read it phonetically. (See Figure 13.22.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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87 Disorders of Reading and Writing Toward an Understanding of Reading Investigators have reported several types of acquired dyslexias, and I will describe three of them in this section: surface dyslexia, phonological dyslexia, and direct dyslexia. surface dyslexia A reading disorder in which a person can read words phonetically but has difficulty reading irregularly spelled words by the whole-word method. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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89 Disorders of Reading and Writing Toward an Understanding of Reading phonological dyslexia A reading disorder in which a person can read familiar words but has difficulty reading unfamiliar words or pronounceable nonwords. direct dyslexia A language disorder caused by brain damage in which the person can read words aloud without understanding them. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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91 Disorders of Reading and Writing Toward an Understanding of Reading Evidence from lesion and functional imaging studies with readers of English, Chinese, and Japanese suggest that the process of whole-word reading follows the ventral stream of the visual system to a region of the fusiform gyrus, located at the base of the temporal lobe. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

92 Disorders of Reading and Writing Toward an Understanding of Reading For example, functional imaging studies by Thuy et al. (2004) and Liu et al. (2008) found that the reading of kanji words or Chinese characters (whole-word reading) activated the left fusiform gyrus. This region has come to be known as the visual word-form area (VWFA). Copyright © 2014 Pearson Education, Inc. All Rights Reserved

93 Disorders of Reading and Writing Toward an Understanding of Reading Once words are identified—by either means—their meaning must be accessed, which means that the two pathways converge on regions of the brain involved in recognition of word meaning, grammatical structure, and semantics. (See Figure 13.25.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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95 Disorders of Reading and Writing Toward an Understanding of Reading The fusiform face area of the right hemisphere has the ability to quickly recognize unique configurations of people’s eyes, noses, lips, and other features of their faces even when the differences between two people’s faces are very similar. For example, parents and close friends of identical twins can see at a glance which twin they are looking at. Similarly, the VWFA of the left hemisphere can recognize a word even if it closely resembles another one. (See Figure 13.26.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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97 Disorders of Reading and Writing Toward an Understanding of Reading Vinckier and his colleagues had adult readers look at the following stimuli: 1) strings of false fonts (nonsensical letterlike symbols) 2) strings of infrequent letters 3) strings that contained infrequent bigrams 4) strings that contained frequent bigrams 5) strings that contained frequent quadrigrams 6) real words (See Figure 13.27 for examples of these stimuli.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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99 Disorders of Reading and Writing Toward an Understanding of Reading Functional imaging showed that some brain regions were activated by all of the visual stimuli, including letter-like symbols, some were activated by letters but not symbols, and so on, up to regions that were activated by real words. The most selective region included the left anterior fusiform cortex (the VWFA), which was activated only by actual words. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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101 Disorders of Reading and Writing Toward an Understanding of Reading Many studies have found that damage to the VWFA produces surface dyslexia—that is, impairment of whole-word reading. A study by Gaillard et al. (2006) combined fMRI and lesion evidence from a single subject that provides evidence that the left fusiform cortex does, indeed, contain this region. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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103 Disorders of Reading and Writing Toward an Understanding of Reading Szwed et al. (2009) note that the most important cues to object recognition (which is the primary task of the visual system) are those that remain relatively constant even when we view objects from different angles. The most reliable of these cues are the ways that lines meet at vertices, forming junctions with particular shapes, such as L, T, and X. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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105 Disorders of Reading and Writing Toward an Understanding of Reading Figure 13.30 shows a drawing and a word with the vertices missing. Can you figure out what they are? (See Figure 13.30.) Now turn the page and look at the same drawing and word with its midsegments missing instead. I think you will find them easier to recognize. (See Figure 13.31.) I found it easier to recognize the drawing and word with the intact vertices (as I suspect you did)—and so did the subjects in the study by Szwed et al. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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107 Disorders of Reading and Writing Toward an Understanding of Reading Recognizing a spoken word is different from understanding it. For example, patients with transcortical sensory aphasia can repeat what is said to them even though they show no signs of understanding what they hear or say. The same is true for reading. direct dyslexia A language disorder caused by brain damage in which the person can read words aloud without understanding them. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

108 Disorders of Reading and Writing Developmental Dyslexias Some children have great difficulty learning to read and never become fluent readers, even though they are otherwise intelligent. Specific language learning disorders, called developmental dyslexias, tend to occur in families, a finding that suggests a genetic (and hence biological) component. developmental dyslexia A reading difficulty in a person of normal intelligence and perceptual ability; of genetic origin or caused by prenatal or perinatal factors. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

109 Disorders of Reading and Writing Toward and Understanding of Writing Writing depends on knowledge of the words that are to be written, along with the proper grammatical structure of the sentences they are to form. Therefore, if a patient is unable to express himself or herself by speech, we should not be surprised to see a writing disturbance (dysgraphia) as well. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

110 Disorders of Reading and Writing Toward and Understanding of Writing In addition, most cases of dyslexia are accompanied by dysgraphia. Longcamp et al. (2005) found that simply looking at alphabetical characters activated the premotor cortex: on the left side in right- handed people and on the right side in left-handed people. (See Figure 13.32.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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112 Disorders of Reading and Writing Toward and Understanding of Writing phonological dysgraphia A writing disorder in which the person cannot sound out words and write them phonetically. People with this disorder are unable to sound out words and write them phonetically. Thus, they cannot write unfamiliar words or pronounceable nonwords, such as the ones I presented in the section on reading. They can, however, visually imagine familiar words and then write them. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

113 Disorders of Reading and Writing Toward and Understanding of Writing Phonological dysgraphia appears to be caused by damage to regions of the brain involved in phonological processing and articulation. Damage to Broca’s area, the ventral precentral gyrus, and the insula cause this disorder, and phonological spelling tasks activate these regions (Omura et al., 2004; Henry et al., 2007). Copyright © 2014 Pearson Education, Inc. All Rights Reserved

114 Disorders of Reading and Writing Orthographic Dysgraphia Orthographic dysgraphia is just the opposite of phonological dysgraphia: It is a disorder of visually based writing. People with orthographic dysgraphia can only sound words out; thus, they can spell regular words such as care or tree, and they can write pronounceable nonsense words. However, they have difficulty spelling irregular words such as half or busy (Beauvois and Dérouesné, 1981); they may write haff or bizzy. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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