PSYC59H3 Chapter Notes - Chapter 3: Acquired Brain Injury, Akinetic Mutism, Carl Wernicke
CHAPTER 03: CLASSIC APHASIA SYNDROMES
INTRO
- APHASIA: An acquired language deficit due to brain injury
o gives us insights to how language is implemented in the brain
o inability to produce, comprehend or repeat language that results from an acquired brain
injury
o does’t ilude laguage distuaes that hae ogeital auses
o excludes these neurological conditions:
▪ hearing problems
▪ articulatory deficits
▪ akinetic mutism
▪ confusional or psychotic states
o only includes linguistic impairments
HISTORICAL BACKGROUND
- scientific investigation for aphasia start in mid-19th century
o marc dax; described association between aphasia and disease of left hemisphere
o paul broca: left hemisphere is dominant for language
o Carl Wernicke: documented new type of aphasia and correctly predicted existence of
several others
o Ludig Lihthei: elaoated eike’s ideas
- By 20th century all major aphasia syndromes were identified
o Identified through soldiers with head injuries
- Most valuable was the advent of MRI
o Localized aphasia
HOW SHOULD DIFFERENT TYPES OF APHASIA BE CLASSIFIED
- Syndromes: a set of symptoms that tend to co-occur statistically
- never was a complete consensus about how the various kinds of aphasia should be categorized
- shea’s hae ee poided though
o differences between schemes reflect different perspectives regarding which criteria
should be used to characterize the syndromes and how fine-grained those syndromes
should be
- localizationist model of the neural architecture of language
o oa’s aphasia = damage to motor center subserving spoken language production
o eike’s aphasia = daage to audito ete = stoes soud iages of ods
o conduction aphasia = interruption of path that projects from auditory centre to motor
centre
o transcortical motor aphasia – interruption of the pathway that projects from the
concept center
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o mixed transcortical aphasia = interruption of both paths connecting auditory and motor
centers with the concept center
o global aphasia = damage to most of the system
- limitations that confront the classification system
o many of the criteria that are used to distinguish between the various syndromes involve
entire modalities or channels of spoken language use production, comprehension and
repetition
▪ this criteria is general
• example: saying repetition is a symptom may serve as a Eurocentric bias
since word order and syntactic constituent structure play important
roles in the grammatical systems of indo-european langauges but not
for non-indo-european languages
o each syndrome depends on specific symptom s being either present or absent, but the
reality is that impairments of various aspects of language production, comprehension
and repetition are matters of degree than all or nothing phenomena
o each syndrome is defined as a collection of symptoms that ypically co-occur but not
every symptom must always be satisfied in order for the overall diagnosis to be given
o each syndrome involves a close connection between a set of behavioral symptoms and
damage toa certain brain region or network of regions but these deficit-lesion
correlations are no means straightforward
o syndromes are not stable over time, especially during the acute phase of recovery,
during the first three months after lesion onset
- GOODGLASS (1993): familiar syndromes of aphasia are the result of modal tendencies for the
functional organization of language in adult human brains
o Hard-wired neural networks that support auditory perception and motor control impose
anatomical constraint on hwo language circuits can be developed and these constraints
cause most brains to gravitate towards certain computational configurations for
language while still allowing a wide range of individual variation
BROCA’S APHASIA
- Leborgne and Lelong ( just read that part pg 76)
- PRODUCTION:
o NONFLUENT: speech that is slow, effortful and halting
▪ Average number of words and average length of words is decreased
o APRAXIA OF SPEECH: speech production disorder that involves an impairment of
articulatory planning mechanisms
o Can be comprised at lower level of sending specific motor commans to the muscles of
vocal apparatus
▪ DYSARTHIA: characterized by disruptions of speed, strength, range, timing or
accuracy of articulatory movements; speech production disorder that involves
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an impairment of motor control over the muscles constituting the vocal
apparatus
o To communicate they fall back on a few formulaic or idiomatic expressions that they can
still produce in a fluent manner
▪ Sometimes called stereotypes
▪ May retain the ability to recite overlearned sequences like days of the week
▪ Utterances are organized into small groupings of one to three words that are
produced effortfully and laboriously
▪ Expressions have minimal syntactic complexity and they consist of content
words with general meanins
▪ Patients are better at accessing nouns than verbs but noun retrieval is impaired
to some degree and often to a great degree
o Most salient feature: patients have difficulty producing grammatical morphemes
▪ These morphemes have schematic meanings and their main role is to contribute
to grammatical structures of sentences
• CLOSED CLASS ELEMENTS: grammatical morphemes like prepositions,
conjunctions and affixes; form a small sset that changes slowly over
history
• OPEN CLASS ELEMENTS: content words like nouns, verbs and
adjectives; form a large set that is easily expanded or contracted
o In speech of these patients, one sees a dissociation between disrupted closed class
grammatical morphemes and less impaired production of open class content words
▪ Together with reduced syntactic complexity, this aspect of the syndrome is
called AGRAMMATISM: deficit involving reduced syntactic complexity and
impaired production of closed class elements
• Can be manifested in different ways that depend on various
grammatical properties of the patients language
o Patients speech is sparse, effortful, slow, syntactically simplified and rhythmically
punctuated by many pauses and false starts
o Moe noun than verbs and adhectives and a paucity of closed-class grammatical
morphemes
- COMPREHENSION:
o Relatively intact understanding of conversation
o Abnormal auditory comprehension
o Has difficulties when asked to point to several different named objects in a specific
sequence
o Has trouble with complex sentences
o Have trouble processing grammatical info not only during speech production but also
during auditory comprehension
- REPETITION:
o Usually better than spontaneous speech, but still abnormal
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Document Summary
By 20th century all major aphasia syndromes were identified. Most valuable was the advent of mri: localized aphasia. How should different types of aphasia be classified. Syndromes: a set of symptoms that tend to co-occur statistically. Leborgne and lelong ( just read that part pg 76) 1874: described a new type of language disturbance that he called sensory aphasia but was the(cid:374) (cid:272)alled wernicke" apha ia. Main symptoms: fluent but semantically incoherent and often phonologically distorted speech production, severely impaired auditory comprehension, defective repetition and unawareness of errors. Lesions in posterior superior and/or middle temporal gyri of the left hemisphere. Production: fluent: speech that flows at a normal rate, sometimes hyperfluent = speak at a normal rate or a faster than normal rate, when their output is excessive, the phenomenon is called logorrhea or press of. Comprehension: patients exhibit impaired understanding of spoken language which is why wernicke himself originally called the syndrome sensory apahasia.
