Dissociations Between Reading Responses and Semantic Priming Effects in A Dyslexic Patient

We report a patient (Y.Y.) with senile dementia of the Alzheimer's type. The patient read aloud some words composed of two or three kanji characters with errors applying typical pronunciations of each character and defined them in keeping with the mispronunciation if the pronunciation represented another real word. The results of single-word semantic priming in a lexical decision task, however, suggested normal recognition processes for these kanji-words, despite the patient's reading errors. We consider her reading to represent surface dyslexia in Japanese. We discuss these dissociations between reading responses and priming effects in the context of dual-route models of human reading, and conclude that the “visual route” (direct access from orthography to semantics and phonology) was not completely disrupted, but partially preserved and functioning in automatic access.     

Surface dyslexia in semantic dementia: a comparison of the influence of consistency and regularity

This study addressed the question of exactly which aspects of spelling-sound consistency influence accuracy of reading aloud in surface dyslexic patients with semantic dementia. Oral reading data were obtained from twelve patients on three sets of words that varied in regularity (defined according to grapheme-phoneme correspondences) and consistency (defined according to the pronunciation of word body neighbours). The patients were less accurate for irregular/inconsistent words, which they commonly pronounced in line with sound-spelling regularities, as expected in surface dyslexia. They produced plausible but incorrect responses for some regular as well as many irregular words, suggesting that their reading performance was influenced by sound-spelling relationships not captured by grapheme-phoneme correspondences. On a set of items that varied consistency and regularity independently, the patients showed a large effect of regularity and a smaller but significant effect of consistency in reading aloud. In addition, there was a correlation between degree of semantic impairment and level of reading accuracy for inconsistent items. These findings are discussed in terms of two influential models of reading: the dual-route-cascaded model (Coltheart et al., 2001) and the triangle model (Plaut et al., 1996). It is argued that the triangle model provides a more straightforward account of the relationship between word comprehension and consistency effects in reading.     

The association between semantic dementia and surface dyslexia in Japanese

One theory about reading suggests that producing the correct pronunciations of written words, particularly less familiar words with an atypical spelling-sound relationship, relies in part on knowledge of the word's meaning. This hypothesis has been supported by reports of surface dyslexia in large case-series studies of English-speaking/reading patients with semantic dementia (SD), but would have increased credibility if it applied to other languages and writing systems as well. The hypothesis predicts that, of the two systems used to write Japanese, SD patients should be unimpaired at oral reading of kana because of its invariant relationship between orthography and phonology. By contrast, oral reading of kanji should be impaired in a graded fashion depending on the consistency characteristics of the kanji target words, with worst performance on words whose component characters take ‘minority’ (atypical) pronunciations, especially if the words are of lower frequency. Errors in kanji reading should primarily reflect assignment of more typical readings to the component characters in these atypical words. In the largest-ever-reported case series of Japanese patients with semantic dementia, we tested and confirmed this hypothesis.     

Developmental dissociations between lexical reading and comprehension: Evidence from two cases of hyperlexia

We report two cases of developmental hyperlexia - JY and AD - who performed at normal levels or above in converting print into speech, but who were very impaired in spoken and written word comprehension. Our investigations focussed on whether these cases displayed evidence for normal acquisition of lexical reading skills, as indexed by unimpaired performance for age in reading aloud a set of irregular words, despite poor acquisition of semantic knowledge of the same words. In both cases, this dissociation was evident. The pattern of results was also demonstrated at an item level: the two cases showed no significant differences in reading accuracy for irregular words which they could define than for those which they could not. The results provide further evidence for the existence of a direct-lexical route from orthography to phonology, which is not necessarily mediated by semantic knowledge.     

Deterioration of word meaning: Implications for reading

We investigated six patients with progressive focal dementia or progressive aphasia, who showed impairments in knowledge of word meaning ranging from moderate to very severe. In all cases, a test of oral word reading demonstrated preserved reading of words with regular spelling-to-sound correspondences (e.g. MINT), but impaired reading of words with atypical correspondences (e.g. PINT). The level of success on these “exception” words was significantly related to word frequency, and the most common error was the assignment of a more typical spelling-sound correspondence. Various explanations are considered for this common association between loss of word meaning and a surface alexic pattern of reading performance.     

Preserved ability to read aloud kanji idioms in left handed alexia]

We report a 69-year-old left-handed man, who developed alexia after a right medial occipito-temporal lobe infarction. On admission to the rehabilitation department two months after the onset, neurological examination showed left hemianopia, left hemiparesis, decreased deep sensation on the left side, and alexia. A brain MRI demonstrated infarcts in the right medial occipito-temporal lobe and the splenium of the corpus callosum. Detailed neuropsychological examination was performed two months after the onset. The patient was alert and cooperative. His speech was fluent with some word-finding difficulty. Comprehension for spoken materials, repetition, and naming abilities were all preserved. Systematic examination for reading revealed that reading aloud was disturbed in both kanji and kana words. Reading comprehension was significantly better for kanji words than kana words. First, we examined the effects of number of characters in a word. The number of characters in a word didn't affect his reading performance. Second, his performance on reading aloud of usual kanji words was compared with that of kanji words representing idioms. A kanji idiom is different from usual kanji words, in which pronunciation of each character is selected from several options. Reading aloud kanji idioms was significantly better than usual kanji words. In addition, reaction time to complete reading a word was much shorter for kanji idioms than usual kanji. An analysis of qualitative features of errors revealed that most errors in kanji idiom reading were semantically similar to the correct answers, while many errors in usual kanji word reading were classified into "don't know" responses. These findings suggested that a kanji idiom was tightly connected to its pronunciation, which resulted in his much better performance for kanji idiom reading. Overlearning of a unique relationship between a kanji idiom and its pronunciation might modify neuronal organization for reading.     

Progressive Anomia with Preserved Oral Spelling and Automatic Speech

We report a patient, Newton, with a progressive classical anomia resulting from focal degeneration of the left hemisphere. In naming tasks Newton spelt aloud picture names that he could not retrieve, indicating a dissociation between orthography and phonology. Unusually, his writing and letter-pointing performance were impaired and spelling was achieved only through alphabet recitation. A study of automatic speech tasks demonstrated strikingly preserved naming performance on automatic compared to nominative tasks. We argue that automatic tasks provide phonological cues that facilitate phonological activation. With progression of disease Newton has shown increasing difficulty reading and repeating words, which we interpret in terms of a progressive elevation in the threshold for activation of phonology. Phonological cueing of picture names has yielded superior naming than word reading and even repetition, a finding consistent with the notion that task characteristics influence likelihood of phonological activation and naming success, but contrary to the notion that there exist separate task-specific output systems. We conclude that Newton exhibits a unique pattern of deficits, which have theoretical relevance for the debate on the relationship between phonology and orthography, the role of automatic speech and the relationship between naming, reading and repetition.     

Progressive anomia with preserved oral spelling and automatic speech

We report a patient, Newton, with a progressive classical anomia resulting from focal degeneration of the left hemisphere. In naming tasks Newton spelt aloud picture names that he could not retrieve, indicating a dissociation between orthography and phonology. Unusually, his writing and letter-pointing performance were impaired and spelling was achieved only through alphabet recitation. A study of automatic speech tasks demonstrated strikingly preserved naming performance on automatic compared to nominative tasks. We argue that automatic tasks provide phonological cues that facilitate phonological activation. With progression of disease Newton has shown increasing difficulty reading and repeating words, which we interpret in terms of a progressive elevation in the threshold for activation of phonology. Phonological cueing of picture names has yielded superior naming than word reading and even repetition, a finding consistent with the notion that task characteristics influence likelihood of phonological activation and naming success, but contrary to the notion that there exist separate task-specific output systems. We conclude that Newton exhibits a unique pattern of deficits, which have theoretical relevance for the debate on the relationship between phonology and orthography, the role of automatic speech and the relationship between naming, reading and repetition.     

Progressive aphasia and surface Alexia in Japanese

Abstract

We report the reading performance of a patient, NK, with selective left-temporal atrophy and progressive aphasia. NK showed surface alexlc reading with the following pattern: flawless oral reading of kana words; a deficit in reading of two-character kanji words that was particularly severe for lower frequency words with an unpredictable correspondence between the component characters and their pronunciations; a predominance of kanji-word reading errors In which characters were assigned pronunciations appropriate to other words containing these characters. These features were predicted and are interpreted on the basis of (a) recent studies of patients with progressive aphasia in English, (b) recent analyses of surface alexia in terms of an interaction between word frequency and neighbourhood-based consistency of spelling-sound correspondences, and (c) characteristics of the Japanese kana and kanji writing systems.     

A functional magnetic resonance imaging study of the tradeoff between semantics and phonology in reading aloud

Using functional magnetic resonance imaging, we explored the role of semantics in mediating orthographic-to-phonological processing in reading aloud, focusing on the interaction of imageability with spelling-to-sound consistency for low-frequency words. Behaviorally, high-imageable words attenuate the standard latency and accuracy disadvantage for low-frequency inconsistent words relative to their consistent counterparts. Neurobiologically, high-imageable words reduced consistency-related activation in the inferior frontal gyrus but increased posterior activation in the angular and middle temporal gyri, representing a possible neural signature of the tradeoff between semantics and phonology in reading aloud. We discuss implications for neurobiological models of reading in terms of understanding the interplay among areas associated with component processes and suggest that the results constitute an important step toward integrating neurobiological and computational models of reading.     

The impact of semantic memory impairment on spelling: evidence from semantic dementia

We assessed spelling and reading abilities in 14 patients with semantic dementia (with varying degrees of semantic impairment) and 24 matched controls, using spelling-to-dictation and single-word reading tests which manipulated regularity of the correspondences between spelling and sound, and word frequency. All of the patients exhibited spelling and reading deficits, except at the very earliest stages of disease. Longitudinal study of seven of the patients revealed further deterioration in spelling, reading, and semantic memory. The performance of both subject groups on both spelling and reading was affected by regularity and word frequency, but these effects were substantially larger for the patients. Spelling of words with exceptional (or more precisely, unpredictable) sound-to-spelling correspondences was most impaired, and the majority of errors were phonologically plausible renderings of the target words. Reading of low frequency words with exceptional spelling-to-sound correspondences was also significantly impaired. The spelling and reading deficits were correlated with, and in our interpretation are attributed to, the semantic impairment.     

An fMRI study with written Chinese

Event-related functional magnetic resonance imaging (ER-fMRI) was used to investigate how the human brain processes phonology and transforms a word's visual form (orthography) into phonological form during reading in logographic Chinese, a writing system that differs markedly from alphabetic languages. We found that reading aloud of irregular words produced larger MR signal intensity changes over extensive regions involving left infero-middle frontal cortex, left motor cortex, right infero-frontal gyri, bilateral anterior superior temporal areas, and anterior cingulate cortex. Right superior parietal lobule, the cuneus in bilateral visual cortex, and thalamus participated in the processing of irregular, but not regular, words. These findings were discussed in comparison to neuroimaging findings from alphabetic languages, as well as in relation to models of reading.     

Writing Kanji without semantics in a case with probable Alzheimer's disease]

We examined a patient (NM) with probable Alzheimer's disease who showed phonologically plausible errors in kanji (logogram) writing. In semantic tasks, she showed no deficits in pointing or naming but had difficulty in more complex tasks such as proverb comprehension. In reading aloud of kanji words, she could read most kanji words correctly and showed little phonologically plausible reading errors. She performed poorly in lexical decision and on-reading of one-letter kanji (Sino-Japanese pronunciation derived from the Chinese language at the time of borrowing). Writing to dictation demonstrated no mistakes in kana letters and words, but many errors in kanji, which were phonologically equivalent but semantically inappropriate. To explore the relationship between the writing errors in kanji words and comprehension of the word meanings, we selected 33 words that she made phonologically plausible writing errors. We gave her the following five tasks using these words; 1) to ask meanings of the words, 2) to dictate the words, 3) to dictate sentences including these words, 4) to discriminate appropriate target words from distracters including her own erroneous responses, and 5) to write these words again. She showed no consistent errors in these tasks. In some occasions, she could write correct kanji words without understanding word meanings. She also showed phonologically plausible writing errors in spite of describing correct word meanings. In Japanese, word meaning deficits like Gogi aphasia were thought to cause phonologically plausible writing errors. As the impairments of word meanings in NM are comparatively mild, the underpinning of her kanji agraphias might be different from that of phonologically plausible errors in Gogi aphasia. It would be suggested that she frequently wrote phonologically equivalent errors because of her lexical deficits in spite that her phonological processing was preserved. Furthermore, she would not necessarily use the semantics (word meanings) of kanji words during dictation.     

Treatment of single word oral reading in an individual with deep dyslexia

Background: Deep dyslexia is an acquired reading disorder in which the lexical and nonlexical reading routes are impaired, resulting in poor nonword reading, semantic errors in oral reading, visual-perceptual errors in oral reading, poor reading of functors, and imageability effects. There is evidence that individuals combine information from the lexical (semantic system) and the non-lexical routes to read words aloud. This evidence shows that partial phonological and semantic information combined at the level of the phonological output lexicon reduces semantic errors in reading aloud and increases the ability to produce the correct words. Aims: The aim of the present study was to use a phonologically based oral reading treatment to treat impaired single word oral reading in an individual with deep dyslexia. We hypothesised that phonologically based treatment would improve oral reading of real words, decreasing the amount of semantic errors. Methods & Procedures: The Wilson Reading System was used in therapy. This phonics-based programme focuses on the use of grapheme-phoneme correspondences, blending, and phonological awareness. A multiple-baseline design was used to evaluate the treatment effects in a single individual with deep dyslexia. Outcomes & Results: Following treatment at the single word level, the individual showed a significant improvement in single word oral reading for the targeted syllabic structure and in nonword reading. There was also a significant reduction in semantic errors in oral reading. One month post-treatment, the individual maintained treatment gains. Conclusions: Results support the hypothesis that the partial use of phonological information, combined with semantic information, results in improved accuracy of oral reading. This suggests that treatment of oral reading in people with deep dyslexia may benefit from attention to the non-lexical (phonological) component of reading in addition to the lexical/semantic component.     

A letter-by-letter reader who could not read nonwords

Letter-by-letter reading is a neuropsychological syndrome characterized by oral reading which seems to be mediated by explicit naming of constituent letters of the printed string. Thus reading time rises abnormally as a function of the length of the items to-be-read. This syndrome is generally interpreted as indicating a disconnection within the normal reading system prior to the activation of the visual and phonological lexical access routes. The patient retains a subsidiary strategy of spelling words by naming their constituent letters and uses this strategy for planning their pronunciation. If this interpretation is correct then reading aloud in letter-by-letter reading should not be affected by the features of the letter string which are stored lexically as the functional disconnection is postulated to occur prior to this stage. In this paper we report the case of a letter-by-letter reader who shows some signs which are puzzling in terms of current interpretations of the syndrome. They can be summarized as follows: (1) The patient reads words better than he reads nonwords; (2) Concrete words are processed more holistically while abstract words are processed more letter-by-letter; (3) Lexical decisions can be made far more rapidly than words can be read aloud. These three signs are very difficult to account for if reading is accomplished solely through a non-lexical reversed spelling strategy. Our experimental investigations of this patient are reported and alternative models assuming strategic control over the reading mechanism are discussed.     

A patient with aphasia using the nonsemantic lexical route for Kanji reading

We report a patient with aphasia, caused by cerebral hemorrhage, who probably used the nonsemantic lexical route when reading words aloud. To investigate the mechanisms underlying her reading dysfunction, we analyzed her reading abilities using the Dual-Route Cascaded Model. Language tests resulted in low correct percentages for both reading comprehension and reading nonwords aloud, suggesting problems in the semantic system and the nonlexical route. Conversely, the patient showed high scores on the reading words aloud task. Although she failed to understand many inconsistent-atypical words in the reading comprehension test, she correctly read most words aloud, suggesting that she used the nonsemantic lexical route. In addition, the lexical reading route was analyzed in detail by using inconsistent-atypical Kanji words as stimuli. Finally, we analyzed her reading dysfunction compared with previous cases.     

Brain mechanisms for reading: the role of the superior temporal gyrus in word and pseudoword naming

The purpose of this study was to test the neurological validity of a dual-route model of reading by asking patients, who were undergoing electrocortical stimulation mapping, to read words with irregular print-to-sound correspondences and pseudowords. Brain activation profiles were also obtained from these patients during an auditory and a visual word recognition task using whole-head magnetic source imaging. We demonstrated that reading is subserved by at least two brain mechanisms that are anatomically dissociable. One mechanism subserves assembled phonology and depends on the activity of the posterior part of the left superior temporal gyrus (STGp), whereas the second is responsible for addressed phonology and does not necessarily involve this region. The contribution of STGp to reading appears to be based on its specialization for phonological analysis operations, involved in the processing of both spoken and written language.     

The interaction between semantic and the nonsemantic systems in reading: Evidence from Chinese

We report a Chinese-speaking patient WJX with left temporal lobe ischemic damage resulting in dementia. Similar to English speaking patients with this pathology, WJX showed impaired semantic system functioning together with a well preserved ability to read aloud Chinese characters including characters with unpredictable mappings between orthography and phonology-so called irregular characters. The summation hypothesis [Hillis, A. E., & Caramazza, A. (1991). Mechanisms for accessing lexical representations for output-evidence from a category-specific semantic deficit. Brain and Language, 40, 106-144; Hillis, A. E., & Caramazza, A. (1995). Converging evidence for the interaction of semantic and sublexical phonological information in accessing lexical representations for spoken output. Cognitive Neuropsychology, 12, 187-227] proposes that the good reading performance can be explained by the integration of a semantic route of reading and a nonsemantic route. Most Chinese characters contain components that can give a clue to the pronunciation (phonetic radical) and the meaning (semantic radical) of the character. We compared his comprehension and oral reading performance by varying the consistency of phonetic radicals and the transparency of semantic radicals. We observed an interaction between WJX's character comprehension and the consistency of the phonetic radical on reading performance; however, the transparency of semantic radicals had no effect on performance. We argue that this case report provides converging evidence for the principles of the summation hypothesis for reading.