10 Language
Psychology 355
Introduction
Language
A. System by which sounds, symbols, and
gestures used for communication
B. Process
1. Language comes into brain through
visual and auditory systems
2. Motor system: Produces speech,
writing
3. Processing between sensory and
motor systems
Psychology 355
2
Specialized Language Areas
Aphasia
A. Partial/complete loss of language
abilities following brain damage
B. Latin Lingua: Thought the tongue
controlled language
C. 1770: Johann Gesner: aphasia is a form
of brain damage disconnecting ideas
from words
D. 1825: Jean-Baptist Bouillard: speech is
controlled by frontal lobes
E. 1861: Paul Brocca:
Cortical area in left3
Psychology 355
frontal lobe
Specialized Language Areas


I.
II.
Wada procedure: Anesthetize single
hemisphere (sodium amytal in left carotid
artery)
Left Hemisphere dominance
Broca’s area
Paul Broca in 1864: Region of dominant left
frontal lobe: Articulate speech, speech
production
Wernicke’s area
Karl Wernicke in 1874: Superior surface of
temporal lobe between auditory cortex and
angular gyrus: Lesions disrupt normal
speech but more so comprehension
Psychology 355
4
Specialized Language Areas
Broca’s Aphasia (motor, nonfluent aphasia)
1. Difficulty speaking, but understand
spoken/heard language
2. Paraphasic errors
3. Pause to search for words, repeat
“overlearned” things, difficulty
repeating words
Psychology 355
5
Specialized Language Areas
Wernicke’s aphasia
A. Speech fluent, comprehension poor
1. Strange mixture of clarity and
gibberish
2. undisturbed by sound of own or
other’s speech
3. Correct sounds, incorrect sequence
4. Incorrect word similar to correct word
5. Comprehension difficult to assess
6. Playing music, writing similar
Psychology 355
6
Specialized Language Areas
A.
B.
C.
D.
Broca’s area
Wernicke’s
area
Arcuate
Fasciculus
Angular gyrus
Wernicke-Geschwind Model
Psychology 355
7
Specialized Language Areas
A.
B.
C.
D.
Broca’s area
Wernicke’s area
Arcuate Fasciculus
Angular gyrus
Psychology 355
8
Specialized Language Areas
Conduction Aphasia
A.
B.
C.
D.
Lesion of fibers composing arcuate
fasciculus
Comparison with Broca’s aphasia,
Wernicke’s aphasia: Comprehension good,
speech fluent
Difficulty repeating words
Symptoms: Repetition substitutes/omits
words, paraphasic errors, cannot repeat
function, nonsense words, polysyllabic
words
Psychology 355
9
Specialized Language Areas
Aphasia in Bilinguals and the Deaf
A.
Aphasia in bilinguals- Language affected
depends on: Order, fluency, use of
language
B.
Sign language aphasias analagous to
speech aphasias  but can be produced
by lesions in slightly different locations
C.
Verbal and sign language recovered
together in one case indicating
overlapping regions used for both
D.
Evidence suggests some universality to
language processing in the brain
Psychology 355
10
Asymmetrical Language Processing
Split-Brain Studies
A. Roger Sperry (1950s)
B. Split-brain procedure
1. Sever axons making up the
corpus callosum
2. No major deficits ?
3. With proper experiments, animals
behaved as if they had 2 brains
Psychology 355
11
Asymmetrical Language Processing
Split-Brain Humans
Psychology 355
12
Asymmetrical Language Processing
Left Hemisphere Language
Dominance
A.
Right visual field,
repeated easily
B.
Left visual field,
difficulty verbalizing
C.
Image only in left
visual field, object in
left hand, unable to
describe
D.
Split-brain: Unable
to describe anything
to left of visual
fixation point
Psychology 355
13
Asymmetrical Language Processing
Language Functions of the Right Hemisphere
A. Functions of right hemisphere: Read
and understand numbers, letters, and
short words (nonverbal response)
B. Baynes, Gazzaniga, and colleagues:
Case of patient with right hemisphere
able to write, but not speak
C. Right hemisphere: Drawing, 3-D
puzzles, sound nuances
D. Prosidy
Psychology 355
14
Asymmetrical Language Processing
Anatomical Asymmetry and Language
A.
Left lateral (Sylvian) fissure
longer and less steep than right
B.
Geschwind and Levitsky:
Left planum temporal larger
than right in 65% cases
C.
Functional human asymmetry:
More than 90% humans
right-handed
D.
Animals: Equal numbers of
right-handers and left-handers,
or no dominance
Psychology 355
15
Language: Brain Stimulation
and Brain Imaging
A.
Old methods: Correlate language
deficits with postmortem analysis of
brain damage
B. Recent techniques
1. Electrical brain stimulation
2. Functional Imaging
Psychology 355
16
Brain Stimulation
A. Motor cortex: Immediate speech arrest
B. Broca’s area: Speech stopped after
strong stimulation,
C. speech hesitation
from weak stimulation
D. Posterior parietal lobe
near Sylvian fissure
and temporal lobe:
Word confusion and
speech arrest
E. Small parts of cortex:
naming, reading,
repeating facial
Psychology 355
movements
17
Brain Stimulation
N, naming difficulty with
intact speech (anomia);
A, arrested speech;
G, grammatical errors;
J, jargon (fluent speech with
frequent errors);
R, failure to read;
M, facial movement errors.
Psychology 355
18
Brain Imaging
fMRI:Record during
language tasks
A. Activated brain
areas consistent
with temporal and
parietal language
areas
B. More activity than
expected in
nondominant
hemisphere Psychology 355
Generate words
from a category
Silently repeat
a heard sentence
Listen to a story
19
Brain Imaging
PET:
Compare
Sensory
responses to
words vs.
Speech
production
Psychology 355
20
Language Acquisition
A.
Mechanism in infants
1. Syllable emphasis
2. Motherese
i.
B.
C.
Adults talk to infants; Speech
slower, exaggerated, vowel sounds
clearly articulated
Complexity: Foreign language
Dehaene-Lambertz: 3 month
infant, brain response to spoken
words similar to adults
Psychology 355
21
Concluding Remarks
I.
Language processing
A. Person repeats word read
II. Initial activity in visual cortex, then activity
in motor cortex corresponding to muscles
that move vocal apparatus
III. Multiple brain areas critical for language
IV. Language skills: Naming, articulation,
grammar usage, comprehension
V. Further brain imaging studies will reveal
more about language systems organization
Psychology 355
22
End of Presentation
Psychology 355