Language Organization
Classic model
Sensory perception--comprehension (WA)--Broca’s
(formulation, motor plan)--motor cortex (final
common pathway)
Language Organization
Classic model
Sensory perception--comprehension (WA)--Broca’s
(formulation, motor plan)--motor cortex (final
common pathway)
Classical conception of aphasia.
Paul Broca (1824-1880).
Mr.Leborgne =TanTan died 4/17/1861
Communication a la Societe
d’Anthropologie (1865)” Je vous ai
communique…….dix observations
d’aphemie dans lesquelles on a trouve
a l’autopsie des lesions diverses de la
3me circonvolution frontale…..Je
persiste a penser que l’aphemie
verbale, c’est a dire la perte de la
parole sans paralysie des organes de
l’articulation et sans destruction de
l’intelligence est liee aux lesions de la
3me circonvolution frontale. Ma
communication est relative a la
singuliere predilection de l’aphemie
pour l’hemisphere gauche du cerveau”
Mr. Leborgne died 4-17-1861
11am
at the age of 51.
MRI of Leborgne 4-151994
Voxel-based Lesion-Symptom
Mapping (VLSM): sample
maps
Fluency
Comprehension
Bates, Wilson, Saygin, Dick, Sereno, Knight & Dronkers, 2002
Disruption model of language function
“Broca’s Area”: PIFG
“Wernicke’s area”:
PT/IP
Reading Area:
Angular Gyrus
Basal Temporal
Language Area
Frontal regions
44 inf
44/6
9/6 Exners area
46
45
47
6 medial
Temporal regions
41/42
22
21/20
37
Parietal: 40 39
1
1
5
4
2
6
8
6
3
3
3
2
7
7
6
8
9
10
10
9
Basal Temporal Language Area
• Mills Naming Center; Nielson’s language
formulation center
• Involved in object naming
• Lesion: Pure anomic aphasia
• Category specificity in more anterior areas
• Believe pathways project ant/sup through insula
1
1
BTLA is difficult to image:
• Major artifacts; need to indicate where
you haven’t signal- false negative risk
• Object naming area: verb generation is
NOT a good activator of this region
Wernicke’s area(s)
• Inferior portion: middle temporal
gyrus/superior temporal sulcus
– Often bilateral activation
• Superior portion: superior temporal
gyrus/supramarginal gyrus
– Posterior/adjacent to TTG
2
2
3
3
Wernicke’s area(s)
• Critical for auditory language comprehension; word
recognition, sequencing phonemes
• Lesions: grammatic speech; multiple paraphasias;
• Superior lesions: phoneme selection deficits,
sequencing deficits; reading problems
• Activations often quite deep in sulci
• Output travels posterior and superior in arcuate
fasciculus
• Lesions of white matter tracts into and out of the
region can lead to serious deficits;These can be
quite distal to the cortical processing areas
• Object naming, word generation --poor activators
Arcuate fasciculus
http://da.biostr.washington.edu/da.html
Frontal language areas
5
4
6
6
9
10
10
9
8
6
Bookheimer 2003 Annual Rev. Neurosci.
Orbital frontal cortex: 47/45
• Arguments about its job: semantics;
verbal selection; selection generally
• Integration of (semantic) information
• Lesion/electrical stimulation: semantic
integration deficits: normal object
naming, grammatic speech; impaired
auditory responsive naming
4
“Broca’s” area: 44 and 45
• Superior to IFS/PCS border, inferior to sylvian
• Focal region; variable in precise location; some
language specificity
• Must exist!
• Lesions: grammatic output; naming; generation;
phoneme monitoring; syntax comprehension;
effortful speech; arrest or anomia with stimulation
6
A
B
Phonology in IFG
Table 1
Bookheimer,
Neuron 2002
ExamplesGelfand
of Syllableand
Stimuli
and Response Characteristics
for Sequencing Tasks
Task
Response
Yes
Match
Syllables
ruk-dup-nid
ruk-dup-nid
Reverse
Syllables
mip-saf-vam
vam-saf-mip
Delete
kiv-zot-fif
Syllables
kiv-fif
Task
No
Response
Yes
ruk-dup-nid
ruk-nid-dup
Match
Hums
mip-saf-vam
vam-mip-saf
Reverse
Hums
kiv-zot-fif
zot-fif
Delete
Hums
No
reverse
delete
match
Exner’s Area
• 6/8 in MFG/PMC
• Associated with pure agraphia
• Appears in many tasks
7
8
Longcamp et al NeuroImage 2003
Matsuo et al Neurosci Lett 2003
Exner’s area vs FEF
Phoneme to grapheme task; saccades
FEF
Exner’s
Stimulated region
Tumor
Stimulated region
Angular Gyrus
• Critical for reading
• Integrates auditory and visual
information
• Pathways from IT to AG, oCC-AG, AGSMG, all vulnerable
7
Reading phrases
Supplementary Speech Area
(Pre-SMA, Speech SMA)
• Important in initiating a motor speech plan
• When removed, get a complete arrest of speech;
lesions may reduce initiation or lead to a
“dwindling aphasia”; comprehension is normal
• Easily reorganizes to intact RH when the
callosum is intact- 1-3 weeks
10
Anterior Insula
• Very often bilaterally symmetric
• When lesioned bilaterally (and selectively):
pure apraxia of speech
• Lesions of area (nearby white matter, IFG,
striatum) lead to profound expressive aphasia
• Do not use to establish laterality; don’t
recommend to remove it either
5
Dorsolateral Pre-frontal Cortex
• Not a language area
• Will show activation, sometimes
unilateral, especially on generation tasks
• Lesions show reduced fluency;
stimulation often produces perseverations
• Don’t use for laterality; often removed in
surgery
8
Language 2
• Reading system and reading disorders
• Right hemisphere contributions to
language
– Prosody
– context
Reading System
• Major issue in reading: 1 or 2 pathways
• Call this the Dual Route model
• Was controversial before functional
imaging- now its pretty well accepted
• Based on differences in acquired alexia
errors
Types of Alexia
• Phonologica, literal or Surface
– Patients read in a letter-by-letter fashion
– They sound out each word
– Errors: they can read pronounceable
nonsense words “migbus”; cannot read
irregular words like “yacht”
– Damage likely to the visual recognition
system in the LH: cant recognize whole
words
Alexia cont.
• Alexia type 2: visual, semantic alexia
–
–
–
–
Can read whole words
Can read irregulars like yacht and pharoah
Cannot read nonsense words
Strong frequency effect- more likely to read common than
uncommon words; better at concrete nouns
– Make visual or regularization errors: lit = light; groal=goal,
etc.
– Apparently have damage to phonological to orthographic
conversion system or to phonological system
Rarer alexias
• Global alexia: affects all reading. AG lesions or WM
exiting visual cortex in LH
• Deep dyslexia: associated with large LH lesionscharacterized by global dyslexia with:
–
–
–
–
–
Visual errors: gird=“girl”
Derivational errors: architecture= architect
Semantic errors: orchestra=symphony
Superior at reading concrete nouns
Suggested to represent some primitive RH whole word
recognition capabilities
Rarer alexias, cont.
• Alexia without agraphia or occipital alexia:
– Most other acquired alexics have impaired writing similar to
reading
– Alexia without agraphia associated with 2 lesions: one in the
left occipital cortex and one in the posterior callosum
– Disruption of visual information into the LH reading system.
Usually accompanied by a field or quadrant cut
– Can write, but cant read what they write
Developmental dyslexia
• Most are similar to the surface alexic
– Difficulty with auditory processing
– Poor at grapheme to phoneme conversion
– Lousy at reading nonwords
– Slow readers; often learn by whole-word
approach
• Rarer, there are visual types and often
some with general language difficulties
Anatomy of Reading
Inferior Frontal
Gyrus
Supramarginal Gyrus (40)
Angular Gyrus (39)
Superior Temporal
Gyrus (posterior)42,41;22
Temporal/Occipital
Junction 21/20/37
Dual Routes
• Inferior Route:
– Occipital V1-V2-V3-IT-insula/44/47
• Superior Route
– V1-V2- AG-ST- IFG 44/6
• Interaction through AG
• Writing: includes SMG and Exner’s
area (46/6 anterior to M1 hand)
Right hemisphere
contributions to language
• Some evidence that early right brain lesions can be
more detrimental to language development than LH
lesions
• LH may process more rapid information. RH may
maintain a context and provide emotional cues to
global meaning
• Some evidence that the ear itself is tuned for more
rapid auditory information in LH or infants (Sininger
2004 Science).
Prosody Paradigm
• Selective attention/stimulus matched
paradigm
• For the 2 prosody conditions:
– “Do the sentences sound alike”
regardless of literal meaning
• For the SC condition:
– “Do the sentences mean the same thing”
regardless of the sound
Affective prosody vs. others
Linguistic vs. Affective
Linguistic Prosody- Left
Affective Prosody- Right
Making Sense of Conversation
(R. Caplan and M. Dapretto, 2003)
• Logical Reasoning
– Q: Do you like having fun?
– A: Yes, because it makes me happy.
• Illogical
– Q: Do you like having fun?
– A: No, because it makes me happy.
•On-topic
–Q: Do you believe in angels?
–A: Yeh, I have my own special angel
•Off-topic (LA)
–Q: Do you believe in angels?
–A: Yeh, I like to go to camp
Reasoning vs Topic
Normal Adults
Topic vs Reasoning in Normal Adults
Reorganized language in early
lesions
• Can see individual patterns using fMRI
• Appears to follow a principle of minimal
energetics: only move what is essential
to move
Initiates speech on the right; language is on the left
Auditory Naming Task
Patient: LH tumor; R handed, R
Brain Speech, Wada confirmed
Rasmussen’s Disease, age
12
Right
Left
Six months post left
hemispherectomy
Right hemisphere
contributions to language
• Sentence level: Topic maintenance vs
logical reasoning
• Understanding metaphor, purpose or
intent of speaker
1
1
5
4
2
6
8
6
3
3
3
2
7
7
6
8
9
10
10
9