Questions Language sharply dissociates from spatial cognition in Williams syndrome. Sign language perception and production heavily relies on spatial abilities (much more than spoken language). Does spatial impairment correlate with linguistic impairment in sign language aphasia? Spatial cognition is heavily right-lateral whereas spoken language is heavily left-lateral. Is sign language as left-lateral as spoken language? What is the relationship between sign and gesture?
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Questions
Language sharply dissociates from spatial cognition inWilliams syndrome.
Sign language perception and production heavily relies onspatial abilities (much more than spoken language).
Does spatial impairment correlate with linguisticimpairment in sign language aphasia?
Spatial cognition is heavily right-lateral whereas spokenlanguage is heavily left-lateral.
Is sign language as left-lateral as spoken language? What is the relationship between sign and gesture?
Why does language “set up shop” whereit does?
Does modality affect the functional neuroanatomy oflanguage?
For example, the M350 localizes in the vicinity ofauditory cortex. Is that just an accident or is it becausethis activity indexes access to representations that areauditory?
Local vs. global hemispheric asymmetries in Deaf signers(Hickok et al. 1998. Brain Lang. 65:276-86)
12 LHD Signers 8 RHD Signers
Two drawing tasks:1. Copy line drawings (BDAE)2. Hierarchical figure task
MM M
M MMMM
M
Spatial cognition in aphasic signers
Trunk Lines
Toe Nails
Eye
Lip
Right Ear Left Ear
Tail
Leg Contour
Chimney
Chimney Line
Window Panes
BushesWindow Sills
Attic Window
Door Knob
Pathway
Double Line on Roof
A of M's
S of J's
G of K's
D of Y's
LHD LHDRHD RHDA. B.
Sign language phonology
Signs are made up of hand shapes
the locations around the body where signs are made
the movements of the hands and arms
orientation of the hands.
SUMMER
UGLY
DRY
A phonological similarity neighborhood in ASL- same hand shape, movement and orientation but differentlocation
ASL morphology
Example of derivational morphology: Adding a rolling movement to the sign “give” (and to most
ASL verb signs) changes the sign’s meaning to “givecontinuously.”
Signers can use different patterns to modify the verb tomean “give to all,” “give to each,” “give to each other”and many other variations.
ASL syntax
No fixed word order (like e.g., Finnish). Grammatical function (subject, object) encoded by
positions in space and direction of movement.
Sign language and iconicity Sign language has more iconicity than spoken language. For
example, many verbs denoting mental states are signed close to thehead.
However, the relationship between signs and their meanings are asconventional as the sound meaning pairs of spoken languages.
Different sign languages such as ASL and BSL mutuallyincomprehensible.
Sign language not “just a loose collection of pantomime-likegestures thrown together willy-nilly”
In fact ability to pantomime does not at all correlate with one’sability to sign…
Corina et al.: Dissociation between Linguistic and NonlinguisticGestural Systems: A Case for Compositionality (1992) Brain andLanguage.
As a result of stroke, WL has a largefrontotemporoparietal lesion in the left hemisphere.
Brodman’s areas 44 and 45 (Broca’s area) and subsequent whitematter tracts, including arcuate fasciculus, were damaged.
Most of middle and posterior area 22 (Wemicke’s area) was notinvolved in the lesion.
WL’s damage
WL does well on spatial cognition tasks. But WL’s signing is severely impaired. Two main types of errors:
Paraphasias (“mispronounciations”)
Substituting pantomime gestures for signs
“Point to the door and then point to the ceiling”
“Will a brick float on water?”Picture naming
WL shows a dissociation both between language and spatial cognition
and between sign and gesture
Lateralization
Hickok, et al. 1996, Nature, 381:699-702
13 LHD Deaf signers10 RHD Deaf signers
Administered a range of clinical aphasia assessment tests (ASLadapted)
Age of Sign Exposure
Onset Deafness Sex
Handed-ness
Age at Testing Lesion Size/Location Lesion Etiology
Left Lesioned:
LHD01 6 5 m r 81 lg/frontal-parietal Ischemic InfarctLHD02 5 5 f r 66 mod/inf parietal Ischemic InfarctLHD03 0 0 f r 37 lg/frontal Ischemic InfarctLHD04 6 1 f r 51 sm/inf-ant frontal Aneurism Rupture*LHD05 13 0 m r 45 lg/temp-par HematomaLHD06 0 0 m r 77 mod/frontal-temp-par Ischemic InfarctLHD07 0 0 m r 86 sm/sup frontal-parietal Ischemic InfarctLHD08 6 2 f r 64 mod/medial occ Ischemic InfarctLHD09 7 < 1 m r 29 mod/frontal-par Hematoma*LHD10 0 2 f r 79 mod/inf-post frontal Ischemic InfarctLHD11 9 < 1 f r 73 mod/frontal-par Ischemic InfarctLHD12 11 0 f r 79 lg/frontal-temp-par Ischemic InfarctLHD13 4 0 m r 71 mod/inf frontal-par Hematoma
Right Lesioned:
RHD01 12 0 f r 71 lg/front-temp-par Ischemic InfarctRHD02 9 5 m r 82 mod/temp-par Ischemic InfarctRHD03 5 0 m r 60 lg/front-temp-par Ischemic InfarctRHD04 0 0 f r 61 mod/sup front-par Tumor* RHD05 0 n/a f r 38 mod/sup par-occ Hematoma*RHD06 0 0 m r 74 lg/front-temp-par Ischemic InfarctRHD07 11 2 f r 78 mod/frontal-par Ischemic InfarctRHD08 7 <1 m r 74 lg/frontal-temp-par Ischemic InfarctRHD09 6 3 f r 83 mod/temp-par Ischemic InfarctRHD10 0 0 f r 78 mod/temp-par-occ Ischemic Infarct
* = surgical intervention
CorticalSubcortical
Left Hemisphere Damage (n=13) Right Hemisphere Damage (n=8)
Superimposed Lesions
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
MELODIC LINE
PHRASE LENGTH
ARTICULATORY AGILITY
GRAMMATICAL FORM
PARAPHASIA INRUNNING SIGN
SIGN FINDING
SIGN COMPREHENSION
1 2 3 4 5 6 7
Absent
1 sign
always impairedor impossible
none available
present in everyutterance
fluent withoutinformation
Absent(z = -2) (z = -1.5) (z = -1) (z = -.5) (z = 0) (z = +.5) (z = +1)
Normal
limited toshort phrases and
stereotyped expressions
runs throughentire sentence
4 signs 7 signs
normal only infamiliar signsand phrases
never impaired
limited to simpledeclaratives and
stereotypes
normal range
once per minute ofconversation
absent
information proportionalto fluency
exclusivelycontent signs
RATING SCALE PROFILE OF SIGN CHARACTERISTICS
Normal
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
Absent limited toshort phrases and
stereotyped expressions
runs throughentire sentence
MELODIC LINE
PHRASE LENGTH
ARTICULATORY AGILITY
GRAMMATICAL FORM
PARAPHASIA INRUNNING SIGN
SIGN FINDING
SIGN COMPREHENSION
1 2 3 4 5 6 7
Absent
1 sign
always impairedor impossible
none available
present in everyutterance
fluent withoutinformation
Absent(z = -2) (z = -1.5) (z = -1) (z = -.5) (z = 0) (z = +.5)(z = +1)
Normal
limited toshort phrases and
stereotyped expressions
runs throughentire sentence
4 signs 7 signs
normal only infamiliar signsand phrases
never impaired
limited to simpledeclaratives and
stereotypes
normal range
once per minute ofconversation
absent
information proportionalto fluency
exclusivelycontent signs
RATING SCALE PROFILE OF SIGN CHARACTERISTICS
Right Hemisphere Damaged (n=7)
MELODIC LINE
PHRASE LENGTH
ARTICULATORY AGILITY
GRAMMATICAL FORM
PARAPHASIA INRUNNING SIGN
SIGN FINDING
SIGN COMPREHENSION
1 2 3 4 5 6 7
Absent
1 sign
always impairedor impossible
none available
present in everyutterance
fluent withoutinformation
Absent(z = -2) (z = -1.5) (z = -1) (z = -.5) (z = 0) (z = +.5)(z = +1)
Normal
limited toshort phrases and
stereotyped expressions
runs throughentire sentence
4 signs 7 signs
normal only infamiliar signsand phrases
never impaired
limited to simpledeclaratives and
stereotypes
normal range
once per minute ofconversation
absent
information proportionalto fluency
exclusivelycontent signs
RATING SCALE PROFILE OF SIGN CHARACTERISTICS
Left Hemisphere Damaged (n=10)
11 LHD Deaf signers 8 RHD Deaf signers
Three ASL comprehension measures1. Single sign-to-picture matching (BDAE)2. Simple commands (one clause, one step)3. Complex commands (multi-clause/-step)“touch all the circles except the yellow circle” “put the blackcircle on top of the red square”
Analysis looked at1. Left vs. right hemisphere damage2. Temporal lobe lesioned vs. spared
temporal lobeinvolved
temporal lobespared
0
.2
.4
.6
.8
1
RHDLHD
Prop
ortio
n Co
rrect
Single signs Simple sentences
0
.2
.4
.6
.8
1
RHDLHD
Prop
ortio
n Co
rrect
0
.2
.4
.6
.8
1
RHDLHD
Prop
ortio
n Co
rrect
Complex sentences Lexical access and the comprehensionof simple sentences depends on the lefttemporal lobe.
Comprehension of complex sentencesstill left-dominant and termporal-dominant, but overall more bilateral.
RHD has been associated with discourse-level deficitsin hearing patients.
The same appears to hold in the Deaf signingpopulation
How stable is the left lateralization of signs?E.g., does it matter which hand you’re signing with?
Does it matter which hand you’re signing with?Answer: No.
The neuroanatomy of sign largely consistent with the neuroanatomyof spoken languages, although research is still conducted at arelatively coarse level, i.e., investigating language laterality ingeneral as opposed to the neural bases of specific operations.
Even though the physical properties of signs and spoken words arevery different, what seems to matter for the brain is that they bothencode a form-meaning relationship that then gets “fed” into thecomputational system of language.