3.3 Alexia and Amusia

What clinical feature defines the acquired disorder known as alexia?

The loss of the ability to read after brain damage or disease.

How does the onset of alexia differ from that of dyslexia?

Alexia is acquired after previous reading competence, while dyslexia is a developmental disorder.

Damage to which brain hemisphere is most commonly associated with alexia?

Left Hemisphere

In attentional alexia, what happens when a patient is presented with a full sentence?

Letters tend to migrate, with one word moving over others.

What is the primary underlying deficit in attentional alexia?

A deficit of attention that is not limited to orthographic material.

Neglect alexia is frequently associated with which neuropsychological condition?

Hemispatial neglect

Which brain region is typically affected in patients exhibiting left-sided neglect in reading?

The right parietal lobe (often via stroke)

Distinguish between subject-centered and object-centered neglect in neglect alexia.

Subject-centered involves omitting the left page side; object-centered involves omitting the left side of individual words.

What is the most frequent type of error produced by patients with neglect alexia?

Substitution errors

In neglect alexia, what happens to word length in the majority of substitution errors?

The length of the words remains generally intact.

Neglect alexia is thought to relate to an attentional deficit in the part of the reading system responsible for coding _____ and _____.

Abstract letters and position information

What defines 'pure alexia' regarding the patient's orthographic and semantic processing?

All aspects of the orthographic lexicon and semantic processing remain intact.

Why is pure alexia often called 'alexia without agraphia'?

Patients can write spontaneously or to dictation but cannot read what they have written.

What compensatory strategy do patients with pure alexia typically use to recognize words?

Reading letter by letter aloud to use their auditory system for recognition.

How does word length affect the reading speed of a patient with pure alexia?

Patients have greater difficulty and take longer with long words.

Where do neural impulses travel after leaving the striate cortex during the reading process?

To the visual association cortex and the angular gyrus.

According to neurological theory, which brain area is central to processing orthographic word forms?

The angular gyrus.

What is the functional result of a lesion to the angular gyrus itself?

Alexia with agraphia (both reading and writing are affected).

Which artery's territory is typically involved in the infarct that causes a disconnection to the angular gyrus?

The posterior cerebral artery.

In pure alexia, why is the patient alexic in both visual fields despite having an intact right calcarine cortex?

Visual input from the right cortex cannot access the left angular gyrus due to a disconnection.

A lesion of the _____, which connects the left secondary visual cortex to the angular gyrus, results in alexia for both hemifields.

Vertical occipital fasciculus.

What is the defining characteristic of surface alexia?

Difficulty reading irregular words while regular words and pseudowords are preserved.

What is a 'regularization error' in the context of surface alexia?

Pronouncing an irregular word according to the standard rules of spelling (e.g., 'island' as 'is-land').

Why do surface alexic patients often confuse homophones like 'would' and 'wood'?

They rely on the phonological code (sound) of the word to access meaning.

Which brain regions are typically involved in the lesions of surface alexia?

The left temporal lobe, temporoparietal cortex, and deep white/gray matter.

What is the primary impairment in phonological alexia?

A disconnection between orthographic units and phonological units, specifically affecting pseudoword reading.

Why is the reading of real words generally preserved in phonological alexia?

Orthographic units can still access semantic units to reach phonological output.

Which vascular event is often associated with phonological alexia?

A stroke in the territory of the middle cerebral artery.

Define semantic alexia.

The preserved ability to read aloud words or pseudowords coupled with a profound impairment in comprehension.

In which patient populations is semantic alexia most frequently observed?

Patients with Alzheimer's disease or semantic dementia.

What is the hallmark symptom of deep alexia?

The production of semantic paralexias.

Semantic Paralexia

A reading error where the produced word has the same meaning as the target but is phonologically/orthographically different.

Identify the type of semantic paralexia error: Reading 'arm' as 'leg'.

Coordinate

Identify the type of semantic paralexia error: Reading 'gun' as 'weapon'.

Superordinate

Identify the type of semantic paralexia error: Reading 'soft' as 'hard'.

Opposite

At what percentage of semantic paralexia errors is a patient diagnosed with deep alexia?

More than 5%

Describe the 'part-of-speech effect' commonly seen in deep alexia.

Nouns and adjectives are read better than verbs, which are read better than functors.

How does concreteness affect reading performance in deep alexia?

Concrete and imageable nouns are read better than abstract and nonimageable nouns.

Deep alexia results from a combined deficit in the direct orthography-to-phonology route and the _____.

Semantic reading route.

How can a clinician distinguish if a deep alexic's error occurs within the semantic system or subsequent to it?

By having the patient point to a picture corresponding to the word after they have read it aloud.

If a deep alexic patient produces a paralexia but points to the correct picture of the target word, where is the deficit located?

Subsequent to semantic processing (in the phonological output).

What was the goal of the treatment program described by de Partz (1986)?

To retrain the patient to read by using the phonological route.

Describe the phoneme-blending technique used in alexia rehabilitation.

Pairing each letter with a common word starting with that letter to force the production of the corresponding phoneme.

What is the 'whole-word approach' used to treat surface alexia?

Teaching patients to recognize irregular words as single units rather than through letter-sound correspondence.

How did Coltheart and Byng (1989) facilitate word recognition in surface alexia?

By pairing written words with mnemonic devices

What is the 'kinesthetic approach' for pure alexia patients who cannot recognize individual letters?

Tracing letters with the finger, head, or eyes to use body movement feedback for recognition.

In pure alexia, damage to the _____ prevents visual information from reaching the language centers in the left hemisphere.

Splenium of the corpus callosum.

Which type of alexia is characterized by a 'regularity effect'?

Surface alexia.

In phonological alexia, which specific type of stimuli is most difficult for the patient to read?

Pseudowords (non-words)

Which brain lobes are generally spared in surface alexia but involved in pure or deep alexia?

The occipital cortex (pure) and the frontal association cortex/Broca's area (deep).

The ability to write spontaneously while being unable to read is the hallmark of which condition?

Pure alexia (Alexia without agraphia).

What is the semantic paralexia error for 'doctor'—'physician' classified as?

Synonym

What is the semantic paralexia error for 'sleep'—'dream' classified as?

Associate.

Which type of neglect involves omitting the last segment (right side) of a printed word?

Right-sided neglect (though less common than left-sided neglect).

Friedman and Robinson (1991) grouped words by _____ to help surface alexia patients.

Pronunciation patterns (e.g., grouping all 'ow' words pronounced as /o/).

What type of stimuli are 'pseudohomophones' in the context of surface alexia?

Non-words that sound like real words, often incorrectly accepted as real by the patient.

Pure alexia patients can usually recognize words when they are _____, even if they cannot read them visually.

Orally spelled out by the examiner.

In the reading pathway, which structure serves as the first cortical destination for visual impulses?

The calcarine (striate) cortex of the occipital lobe.

Damage to the vertical occipital fasciculus typically results from an infarct in which arterial territory?

The posterior cerebral artery.

What does the term 'orthographic alexia' refer to?

Surface alexia.

In neglect alexia, what happens to the effect if the orientation of the words on the page is changed?

The effect (omission or substitution) often disappears.

How does pure alexia affect a patient's visual field?

It typically results in a right visual field defect (hemianopia).

Which alexia type is most clearly associated with the supramarginal gyrus?

Phonological alexia.

In deep alexia, how do functor word errors typically manifest?

Through functor word substitutions.

Why is the semantic route impaired in deep alexia?

Because of an inability to use the direct orthography-to-phonology route combined with a semantic system deficit.