Transcript Slide 1
Language
Ref: Banich pp. 361-364
Broca's Aphasia: Typical Features
• Slowed, effortful speech, with many pauses
• Poor articulation
• Speech may be telegraphic
• Comprehension largely preserved
Wernicke's Aphasia: Typical Features
• Fluent, well articulated speech, function words
• May sound “empty” of content
• Word substitution errors:
phonemic paraphasias
semantic paraphasias
neologisms
e.g. castle -> "cacksel"
e.g. camel -> "horse"
e.g. queen -> "robbli”
• Comprehension impaired
Classical Model of Language
• Broca's area = production ("articulatory images" of words)
• Wernicke's area = comprehension ("auditory images")
• Info is transmitted between the two:
Two Problems with Classical Model
1.
Predicted Patterns Never "Absolute“
2.
Symptoms can dissociate
• e.g. Wernicke's aphasia:
neologisms vs. semantic paraphasias
Current View of Language
•
Linguistics and Cognitive Psychology:
language seen as a complex hierarchical system.
•
Can describe language at a number of levels:
1. Phonological: what are the basic phonemes (sound
units) used to build words?
2. Syntactic: what are the rules for combining words
into sentences?
3. Semantic: what are the meanings of words, and how
does meaning change when words are combined in
sentences?
Current View of Language
• By this view, speech production and comprehension not
unitary processes, but involve multiple components.
For example:
• Production = syntactic planning, word selection, retrieval
of phonemes, articulatory programming
• Comprehension = auditory processing, access to word
meanings, syntactic processing.
Current View of Language
• For many individuals, syndromes don’t work
• Therefore, some researchers now prefer the terms
Fluent and Nonfluent Aphasia:
Nonfluent aphasia:
• Anterior damage (usually)
• Covers Broca’s aphasia, as well as P’s with just one
or two features
Fluent aphasia:
• Posterior damage (usually)
• Covers Wernicke’s aphasia, as well as P’s with just
one or two features
Some Language Components
All of these can become selectively impaired:
Anterior (around Broca’s area):
• Articulation of speech
• Understanding syntactic relationships
Posterior (around Wernicke’s area):
• Retrieval of phonemes for production
• Selection of words for production
• Access to semantic info about words
Some Language Components
All of these can become selectively impaired:
Anterior (around Broca’s area):
• Articulation of speech
• Understanding syntactic relationships
Posterior (around Wernicke’s area):
• Retrieval of phonemes for production
• Selection of words for production
• Access to semantic info about words
i. Articulation of speech
Function of this Component:
• Generation of motor programs
or articulating words
Location:
• Overlaps with Broca’s area
Effects of Damage:
• Speech is halting, effortful
• Words may sound distorted
• P knows the sounds in words, but can't articulate
ii. Retrieval of phonemes
Function of this Component:
• Retrieval of stored info. about
the sounds that make up words
Location:
• Posterior: close to (partially
overlapping?) Wernicke’s area
Effects of Damage:
• P can articulate well
• BUT don't know which sounds to articulate
• Phonemic paraphasias in all speech situations…..
ii. Retrieval of phonemes (cont.)
Examples of phonemic paraphasias:
um.. tornet, no that's not right.. t.. turry-.. no.. turkey.. no... oh
gosh.. tur-.. turk-... turking..
that's wrong what's the end
part?.. um.. I can't remember...
other examples: castle -> cacksel
apron -> aben
refrigerator -> redjerfredjer
iii. Access to semantic info
Function of this Component:
• Accessing word meanings
• Involved in both production and comprehension
Location:
• Posterior -> temporal lobe, some
overlap with Wernicke’s area
Effects of Damage:
• P can’t define words
• Can’t match a word to its meaning
• Semantic paraphasias in speech...
iii. Access to semantic info (cont.)
a. Poor word definition:
bed: "Bed, bed, I don't
know what that is"
swan: "Swan, that
sounds familiar, I'm
sure I once knew it“
b. Failure at word-picture
matching:
Which is a picture of a newspaper?
iii. Access to semantic info (cont.)
c. Semantic paraphasias in speech and naming:
That’s some kind of animal, isn’t
it. A seal, is it?
other examples:
camel -> horse
son -> daughter
walking -> running
Anterior vs. posterior language areas
The general rule:
• Anterior = output
• Posterior = input
• This is broken here!
e.g. phoneme retrieval - posterior region, but affects output
more examples in later lectures…
• How do we explain this?
Anterior vs. posterior areas (cont.)
Posterior language regions (LH) are involved in:
Storage/retrieval of familiar, well-learned relationships
e.g. phoneme sequences of common words
meanings of common words
Anterior regions are involved in:
Generation of new combinations
e.g. sentences (novel combinations of words)
articulation (must be done afresh each time)
More about anterior/posterior differences in upcoming lectures…