14. human communication

4 kinds of verbal behaviors

• talking

• understanding speech

• writing

• reading

are verbal behaviors lateralized?

yes

verbal behavior left hemisphere is dominant for

language

Wada test

determines hemispheric dominance for VERBAL communication (injection of intracarotid sodium amobarbital)

what does the right hemisphere do?

plays a role in the expression and recognition of emotion and in processing tone of voice

aphasia

disturbance in speech

2 kinds of aphasia

• production - “expressive aphasia”

• comprehension - “receptive aphasia”

what is aphasia NOT the result of?

• lack of motivation

• sensory/motor deficit (e.g., paralysis)

in most ppl, what can aphasia result from?

dmg to the left hemisphere

Broca’s area

controls speech

Broca’s aphasia (cause, characteristics)

results from dmg to the inferior left frontal lobe

slow, laborious speech

• spoken words have meaning (are intelligible)

• person can comprehend the speech of others, as long as it isn’t too long or sequential

what kind of words do those w Broca’s aphasia have trouble with? what kinds of words are they better w?

difficulty w FUNCTION WORDS - relational words like a, the, in, about

better w CONTENT WORDS - nouns, verbs, adjectives, adverbs

3 primary speech difficulties in Broca’s aphasia

• agrammatism

• anomia

• difficulty w word articulation

agrammatism

difficulty in using grammar rules (e.g., -ed)

anomia

difficulty in finding appropriate words

periaqueductal area

species-typical behavior, associated w vocal output

lesion in periaqueductal gray area

produces no “ribbits” (mutism), also causes mutism in humans too

Wernicke’s area + location

responsible for language comprehension

superior left temporal gyrus

word salad

produce string of words that don’t make any sense together, symptom of Wernicke’s aphasia

Wernicke’s aphasia + 2 primary symptoms

word recognition is disrupted

• poor speech comprehension

• fluent, but meaningless speech - word salad

what kind of deficits are involved in Wernicke’s aphasia?

receptive deficits

pure word deafness

disruption of inputs to Wernicke’s area results in an inability to understand speech

left superior temporal

processes the sequence of sounds (i.e., word recognition)

are those w Wernicke’s aphasia aware of their deficits?

no, so they experience no frustration

what can those w Wernicke’s area identify?

sounds and animals, prosody (emotional content)

transcortical sensory aphasia + location, symptoms

damage to posterior language area

surrounds Wernicke’s area

• person CAN repeat statements, but does not comprehend the statements - echolalia

• cannot follow simple directions

in order to speak, signals go from…

association areas → posterior language area → Wernicke’s area → Broca’s area

difference btwn Wernicke’s area and PLA

Wernicke’s area is for RECOGNITION of words, PLA is for COMPREHENSION of words

note that Wernicke’s aphasia is caused by damage to both regions

arcuate fasciculus

connects Wernicke’s area w Broca’s area, carries info abt word sounds

damage to fasciculus produces…

conduction aphasia

conduction aphasia symptoms

• fluent, meaningful speech

• good word comprehension

• DIFFICULTY IN REPEATING WORDS (can never repeat non-words), especially complex sentences

example of someone w conduction aphasia having trouble w complex sentence repetition

experimenter: "the auto’s leaking gas tank soiled the roadway”

patient: “the car’s tank leaked and made a mess on the street”

the arcuate fasciculus conducts …, not …

sounds, meanings

prosody

refers to variations in rhythm, pitch, and cadence that communicate info

2 things prosody is severely disrupted by

• damage to right hemisphere

• damage to Broca’s area

receptive aphasia

can’t understand the prosody/emotion of words

prosody reception occurs purely in what brain area?

right cerebral

pure alexia (alexia without agraphia)

the inability to read — can’t see from RVF, can’t read from LVF

what produces pure alexia? what conditions cause thsi damage?what symptom does this produce?

damage to the left visual cortex AND the posterior end of the corpus callosum (splenium)

left posterior cerebral artery stroke or hemorrhage

person can write, but cannot read what they wrote

flow of info during reading

retina → striate cortex → extrastriate → corpus callosum → ipsilateral extrastriate → Wernicke’s area → Broca’s area

damage to only left visual cortex

anopsia in right visual field

damage to only splenium

alexia in left visual field but not right visual field

reading involves 2 processes

• recognition of the entire word (whole-word approach)

• sounding out the word, letter by letter (phonetic approach)

dyslexia

faulty reading

acquired dyslexia

brain dmg causes ppl who previously could read to not read

2 kinds of acquired dyslexias

• phonological dyslexia

• surface dyslexia

phonological dyslexia + cause

person can read using the whole-word method, but cannot sound out words (CAN understand words)

usually left frontal lobe dmg, but may extend back to Wernicke’s

what words can those w phonological dyslexia read?

can read only words that they are familiar with or one letter at a time

surface dyslexia + cause

deficit in whole-word reading (can sound words out and understand them)

left lateral/inferior temporal lesion

what brain area processes words?

fusiform face area (expertise area), SPECIFICALLY the visual word form area (VWFA)

what kind of words can those w surface dyslexia read?

words that have the same sound as spelling, but not good with other words (ex: will pronounce sew as sue)

agraphia

any type of disability involving writing (not due to perceptual or motor deficits)

2 major types of agraphia

• phonological dysgraphia

• orthographic dysgraphia

phonological dysgraphia + cause

unable to sound out words to write them

damage to Broca’s area

orthographic dysgraphia + cause

can only write words by sounding them out

damage to left visual word-form area

what specifically can those w phonological dysgraphia write and can’t write?

• CAN write familiar words (easy - dog, hard - busy)

• CANNOT write pronounceable nonwords (e.g., glab, chint)

what specifically can those w orthographic dysgraphia write and can’t write?

• CAN write ‘easy’ words like “dog” or “tree”

• CANNOT write words in which phonology does not equal spelling

  • busy = bizzy, half = haff