2.3 To link lesions of the temporal lobe to language, memory and emotion disorders

Question 1

Language disorders

Standard language function

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Answer 1

Depends on the complex interactions of sensory intergration and symbolic association, motor skills, learned syntatical patterns, and verbal memory.

Question 2

Aphasia

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Answer 2

Language disorder apparent in speech, in writing (agraphia) or in reading (alexia) produced by injury to brain areas specialised for these functions.

Question 3

Disorders of comprehension

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Answer 3

1. Poor auditory comprehension
2. Poor visual comprehension

Question 4

Disorders of production

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Answer 4

1. Poor articulation
2. Word-finding deficit (anomia)
3. Unintended words or phrases (paraphasia)
4. Loss of grammar and syntax
5. Inability to repeat aurally presented material
6. Low verbal fluency
7. Inability to write (agraphia)
8. Loss of tone in voice (aprosodia)

Question 5

3 categories of aphasia

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Answer 5

1. Fluent aphasia: fluent speech but difficulties either in auditory verbal comprehension or in the repetition of words, phrases, or sentences spoken by others.
2. Nonfluent aphasia: difficulties in articulating but relatively good auditory verbal comprehension.
3. Pure aphasias: selective impairments in reading, writing, or recognizing words in the absence of ther language disorders.

Question 6

Fluent aphasias

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Answer 6

Are impairment related mostly to language input or reception. The impression of a listerner who did not speak the language of a fluent aphasic would be that the subject was speaking easily and correctly.

Question 7

Syndromes of fluent aphasia

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Answer 7

• Wernicke’s aphasia (sensory aphasia)= inability to comprehend words. Word salad. Three characteristics:

1. Classifying sounds
2. Producing speech
3. Writing

• Transcortical aphasia (isolation syndrome): cannot speak spontaneously –> could be because words don’t arouse associations
• Conduction aphasia: cannot repeat words. –> disconnection between perceptual word image and the motor system producing the words.
• Anomic aphasia: difficulty finding the names of objects. –> result from damage throughout the temporal cortex.

Question 8

Nonfluent aphasia

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Answer 8

Broca’s aphasia.

Person understands speech but had to labour to produce it.

Person speaks in short phrases, interspersed with pauses, makes sound errors, makes repetitive errors in grammar etc.

Question 9

Nonfluent aphasia

Transcortical motor aphasia

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Answer 9

Repitition is good, but sponteneous production of speech is laboured.

Question 10

Nonfluent aphasia

Global aphasias

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Answer 10

Speech is laboured and comprehension is poor.

Question 11

Pure aphasias

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Answer 11

1. Alexia: inability to read
2. Agraphia: inability to write
3. Word deafness: cannot hear or repeat words.

Question 12

Nonfluent aphasia, 5 symptoms

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Answer 12

1. Apraxia of speech (difficulty in producing sequences of speech sounds) –> comes from damage to insula.
2. Impairment in sentence comprehension: associated with damage to the dorsal bank of the superior temporal gyrus and in the middle temporal gyrus.
3. Recurring utterances, stems from damage to the acuate fisciculus
4. Impairment in articulation of sound, associated with damage to ventral frontal cortex.
5. Impairment in working memory for sentences, is associated with damage to ventral frontal cortex.

Question 13

Fluent aphasia: What kind of damage mostly?

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Answer 13

Most of the core difficulties, especially the lack of speech comprehension, come from damage to the medial temporal lobe and underlying white matter.

Damage in this area destroys local language regions and cuts off most of the occipital, temporal, and parietal regions from the core language region.

These pat’s appaer to have impairment in the “iconic” memory for sounds, but are not impaired in comprehension.

Question 14

Subcortical language components

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Answer 14

• Language deficits most likely derive from subtle damage to the neocortex.
• Thalamus is thought to influence language function by activating the cortex. When thalamus is damaged, a variety of speech and language disturbances have been found in association with lesions of the left ventrolateral thalamus or the pulvinar nucleus or both.

Question 15

Right-hemisphere contributions to language

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Answer 15

Has little or no speech, but good auditory conprehension of language, including both nouns and verbs.

Some reading ability but little writing ability.

It has little understanding of grammatical rules and sentence structures (synactic processing).

Question 16

Left hemispherectomy

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Answer 16

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It produces severe deficits in speech but leaves surprisingly good auditory comprehension.

Reading ability is limited, and writing is usually absent.

It appears to result in language abilities reminiscent of those achieved by the right hemisphere of commissurotomy patients. So the right hemisphere has language comprehension and the left hermisphere’s contribution to language is syntax.

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Question 17

Neuro assessment

Aphasia test batteries contain:

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Answer 17

Varied subtests that systematically explore the subject’s language capabilities.

They typically include tests of:
1. Auditory and visual comprehension
2. Oral and written expression
3. Conversational speech

Question 18

Model building

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Answer 18

Is the most objective approach to studying reading. Reading models are used to test reading-disabled people, both as a way of defining the impairment and as a way of testing the model’s utility.

Question 19

Model-building approach

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Answer 19

Reading= composed by a number of independent skills or subsystems, one or another of which may not be functioning in an impaired reader.

The modelling approach thus differs from classical neurological approaches in two ways:
1. The latter define dyslexia according to whether it arises in conjunction with other disorders, such as dysgraphia or dysphasia
2. The primary intent is to correlate the impairment with the locus (locatie) of brain damage.