Chapter 8 Prevalence and Theories of Aphasias

Question 1

Aphasia defined (Brookshire, 2003)

Answer 1

A disorder characterized by impaired comprehension and production of language, usually caused by pathology affecting the language-competent half of the brain

Question 2

Prevalence of aphasias

Answer 2

• -Over one million survivors of strokes will have aphasia
• -Women patients with aphasia outnumber all men with aphasia
• -Broca’s aphasia is more common in younger patients and Wernicke’s is more common in older patients

Question 3

Localizationalists’ theory

Answer 3

Believe different parts of the brain specialize in different functions, Broca and Wernicke strengthened this theory with their discoveries of areas of the brain that were damaged and that caused speech and language deficits

Question 4

Cerebral dominance

Answer 4

Localizationists believed the left hemisphere was dominant for speech and language but this was found not to be true because children with insults to the left side of the brain are cable of developing normal language

Question 5

85%

Answer 5

% of adults that are left hemisphere dominant for language

Question 6

Left handers

Answer 6

Have less severe aphasia and recover better

Question 7

Holistic theory

Answer 7

Believe brain functions as an integrated unit and a lesion in one area affects function in many areas (opposite of localizationists’)

Question 8

Connectionist theory

Answer 8

Believe the region surrounding the perisylvian area in the left hemisphere is important for language but don’t limit themselves to just one area (used currently as the best model)

Question 9

Comprehension of speech using connectionist model

Answer 9

• Auditory message is received by ear, travels through ear to brain stem to primary auditory cortex in each hemisphere.
• The info from the auditory cortex in the right hemisphere is sent to Wernicke’s area via the posterior corpus callosum.
• Info from left hemisphere goes to Wernicke’s via association fibers.
• Wernicke’s area receives the info and sorts through its semantic store of info to select word meanings for the words, then it looks up syntactic rules to determine the syntactic relationship among words, then determines an overall meaning of the message.

Question 10

Comprehension of Printed Materials using connectionist model

Answer 10

-Visual info sent to primary visual cortex which encodes the info in a way that Wernicke’s area can understand and sends the info to Wernicke’s area.
-The info from the right hemisphere is sent to the left hemisphere via the posterior corpus callosum.
-Info from left hemisphere goes to Wernicke’s via association fibers.)
Wernicke’s area processes the info in the same way it processes auditory info.

Question 11

Spontaneous speech using connectionist model

Answer 11

-Wernicke’s area retrieves from its lexicon the words needed for the message and using correct syntax, semantic and phonological rules. Then it constructs a sentence.
-Wernicke’s sends the sentence through the arcuate fasciculus to Broca’s area.
Broca’s area puts the code into an action plan and sends than plan to the primary motor cortex.
-Primary motor cortex sends it via the pyramidal tract to the cranial nerves-which causes speech muscles to move.

Question 12

Repetition using connectionist model

Important test because it tests the entire language circuit.*

Answer 12

-Person is asked to repeat a word, etc.
Auditory info travels to the primary auditory cortex, where this incoming message is perceived and translated into a code that Wernicke’s knows.
-This coded message is sent to Wernicke’s.
-Wernicke’s area interprets this info then codes the sentence again into correct semantics, syntax, phonology and sends it to Broca’s area via arcuate fasiculus.
Broca’s area recodes it into a plan for the primary motor cortex and sends it on to speech muscles.

Question 13

Writing using connectionist model

Answer 13

• Wernicke’s area forms a message with appropriate semantics, and syntax, selects letters to spell and sends it through the arcuate fasiculus to premotor cortex for the hand and arm.
• After the plan is set up in the premotor cortex, that info is sent to the primary motor cortex and from there on through to the hand and arm via corticospinal tract to execute.
• Note that it goes to the premotor cortex before going to the primary motor cortex.