Wikipedia:WikiProject Dyslexia/Alexia resources


Alexia is a very complex topic. There are many forms of grouping, and many subtypes in each grouping. On going research continues to provide a greater understanding of the neurological issues which can cause Alexia, which can result in new subtypes, new Theoretical Models of Reading, and even new classifications.

So we need research resources to provide both in depth information and citations, for the what is accepted at this point in time and at all times in the future.

The starting place original Neuroanatomical classifications, To help define the various sub various sub variation which clinicians and researcher were seeing, the Psycholinguistic or cognitive Models of Reading were developed to provide better perspective of Alexia. There are two Psycholinguistic Alexia groups, the Central Alexia group and the Peripheral Alexia group, each of which have their own sub types of Alexia (see below)

Neuroanatomical classifications

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Alexia with Agraphia

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which is now known as Central Alexia or Central Dyslexia and as a result Psycholinguistic sub classifactions currently has 4 subtypes (see below)

From Aphasia, Alexia, and Oral Reading (2004)A Review by L. R. Cherney

Alexia with Agraphia (Parietal-temporal alexia) is characterized by impairments of both reading and writing, with the writing impairment usually equal in severity to the alexia. Patients display difficulty in comprehending written material that is read silently as well as in reading out loud. Reading of letters and words is impaired, and this difficulty extends to comprehension of numbers and musical notations. The problem with letter identification is not restricted to the visual modality; patients also have problems recognizing words when they are spelled aloud. Parietal-temporal alexia is often associated with a fluent paraphasic aphasia.

Alexia without Agraphia

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  • Referred to as Pure Alexia
  • Also known as Global dyslexia, letter-by-letter (LBL) dyslexia, spelling dyslexia, word-blindness, word-form dyslexia.

From Aphasia, Alexia, and Oral Reading (2004)A Review by L. R. Cherney

Alexia without agraphia (occipital alexia) is easily recognized because it is characterized by a disturbance of reading contrasted with relatively preserved writing skills. Patients typically cannot read what they have just finished writing. The difficulty with letter and word recognition is specific to the visual modality, and patients can spell out aloud and recognize words spelled to them by the examiner. Therefore, alexia without agraphia is also called pure alexia, pure word blindness, or agnosic alexia. Letter naming, although initially slow, improves with practice, and the patients often learn to read the individual letters of the word aloud and then decipher the words from their oral spelling.

Frontal Alexia

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  • also known as the "Third Alexia"

From Aphasia, Alexia, and Oral Reading (2004)A Review by L. R. Cherney

In patients with frontal alexia, reading comprehension is typically limited to a few single words, usually content words. Reading comprehension of function words such as prepositions and pronouns is impaired. In contrast to their ability to recognize some words, patients are unable to read the individual letters of the word. Spelling words out loud and comprehension of words that are spelled aloud is also poor. A severe agraphia accompanies the alexia, with writing characterized by poorly formed letters, omission of letters, and agrammatic sentences. Frontal alexia is typically associated with a nonfluent aphasia


Spatial Alexia

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The most recent subtype to be added to the Neuroanatomical group.

Theoretical Models of Reading

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There are quite a few models all of which are modified as research increases our understanding of the cognitive processes and how they interact when we perform the task of reading, or not in the case of Alexics, who prior to their form of brain damage were able to read.

A basic diagram which outlines most of the Psycholinguistic Model of normal reading

Diagram Outlining a Model of the Normal Reading Process
Vision
←— Perceptual Analysis
Letter Sound Converter Visual Word Store —→ Semantic Processor
—→ Phonological Processor ←—
Speech

Psycholinguistic - Central alexias

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  • Also known as Alexia with an Aphasia
  • 4 subtypes, the researchers prefer to call them dyslexias

Deep dyslexia

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Deep dyslexia

Diagram Outlining a Model of the Deep Dyslexia Reading Process
Vision
Perceptual Analysis —→
Semantic Processor
Phonological Processor ←—
Speech

Phonological dyslexia

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Diagram Outlining a Model of the Phonological Dyslexia Reading Process
Vision
Perceptual Analysis
Visual Word Store —→ Semantic Processor
Phonological Processor ←—
Speech

Semantic dyslexia

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Semantic dyslexia

Diagram Outlining a Model of the Semantic Dyslexia Reading Process
Vision
←— Perceptual Analysis
Letter Sound Converter Visual Word Store
—→ Phonological Processor
Speech

Surface dyslexia

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Diagram Outlining a Model of the Surface Dyslexia Reading Process
Vision
←— Perceptual Analysis
Letter Sound Converter
—→ Phonological Processor
Speech

Psycholinguistic - peripheral alexias

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Pure alexia

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Pure alexia

Neglect alexia

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Attentional alexia

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Hemianopia alexia

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which was until recently included as Attentional alexia.


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Aphasia

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Fluent aphasias

Nonfluent aphasias

"Pure" aphasias

Dementia

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main page article dementia

Stroke

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Resources

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The understanding of Alexia, acquired dyslexia, has radically progressed from the late 19th Century. It would probably be best to list resources such as books, research papers, etc. in chronological order by decade so that sources can be compared using the research based understanding of that particular time frame.

1960s

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  • Geschwind N (June 1965). "Disconnexion syndromes in animals and man. I". Brain. 88 (2): 237–94. PMID 5318481.
  • Geschwind N (September 1965). "Disconnexion syndromes in animals and man. II". Brain. 88 (3): 585–644. PMID 5318824.

1970s

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  • Benson DF (June 1977). "The third alexia". Arch. Neurol. 34 (6): 327–31. PMID 860935.
  • Marshall, John; Freda Newcombe (September 1973). "Patterns of paralexia: A psycholinguistic approach". Journal of Psycholinguistic Research. 2 (3): 175–199. doi:10.1007/BF01067101.

1980s

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1990s

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2000s

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2010s

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Medlink - Alexia (a summary)