aarhus 2010-09-10 complexity brain - aarhus universitet · peter].’*ref>>nref& [oyr...
TRANSCRIPT
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Syntac-c complexity and the brain
Workshop on Aphasia and Syntac-c Movement Aarhus, Sept. 10, 2010
Ken Ramshøj Christensen Dept. of Language, Literatuer & Cultur, AU
MINDLab, Center for Func-onelly Integra-ve Neuroscience (CFIN), AUH
hPp://www.hum.au.dk/engelsk/engkrc/ [email protected]
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Broca’s aphasia / Agramma-sm
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Produc-on deficits in agramma-sm • Non-‐fluent, effor\ul speech
• Inability to organize words into gramma-cal sentences
• Improper use or non-‐use of gramma-cal words and morphemes, – C, P, Aux, Tns, Agr…
• Defec-ve ability to assemble phonemes into words (also in Wernicke’s aphasics) – but no non-‐words.
• Impaired ability to repeat sentences they hear. – Even the ones they fully
understand, much to their own surprise and dismay.
• NOTE: Word order is intact
(Pinker 1994: 47)
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Comprehension deficits • Many aspects of comprehension are not impaired (cf. Grodzinsky 2000:4)
• No problems with simple sentences without movement or with universal quan-fiers (Saddy 1995) – Ac-ve (intact): The girl kissed the boy – Passive (impaired): The boy was kissed by the girl – Passive (intact): Every/the boy was kissed by every/the girl
• No impairment to the part of LEX that interfaces with SYNTAX – Able to detect viola-ons of subcategoriza-on
• She ate the cake/*rock/*from
– Able to detect viola-ons of argument structure • She bought a book, *She bought, She bought him a book • *She slept a book, She slept, *She slept him a book,
• No problems with certain types of binding (coreference) (Grodzinsky et al. 1993) – Corefence (intact): Is Mama Bear touching herself? – No coref. (impaired): Is Mama Bear touching her? – With quan-fier (intact): Is every bear herself / her?
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Comprehension deficits • Problems with seman-cally reversible sentences with movement.
• The Trace-‐DeleDon Hypothesis (Grodzinsky 2000): In agramma-sm, traces in θ-‐posi-ons (structural posi-ons to which θ-‐roles are assigned) are deleted from the syntac-c representa-ons.
– (Except if ∀ is present, Saddy 1995)
• The Default Strategy: Referen-al NPs with no θ-‐role are assigned one by default, by linear considera-ons (NP1=AGENT).
Example Reversible Movement Impaired The woman drove the car No No No The car was driven _ by the woman No Yes No The woman kissed the man Yes No No The man was kissed _ by the woman Yes Yes Yes
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Produc-on deficits in agramma-sm (cont.)
• Determined by +/-‐zero-‐morphology – Omission if the bare V/N-‐stem is a real and well-‐formed word [+zero-‐morph]
• English, Japanese – Subs-tu-on if omission results in nonwords [-‐zero-‐morph]
• Russian, Hebrew, Italian
• Furthermore, it is determined by the structural posi-on: Tns > Agr
• Certain types of embedded clauses (Friedmann 2001) – Finite [+Tns] (impaired): I think [(that) she is lazy].
Someone [who annoys people] is not popular.
– Nonfinite [-‐Tns] (OK): I consider [her lazy / to be lazy]. Someone [annoying people] is not popular
Stem Tns Agr
(Ich) kauf -‐ -‐e PRES-‐1ST.SG
(Du) kauf -‐ -‐st PRES-‐2ST.SG
(Ich) kauf -‐t -‐e PAST-‐1ST.SG
(Du) kauf -‐t -‐est PAST-‐2ST.SG
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Produc-on deficits in agramma-sm (cont.)
Neg’
CP
C’
NegP
Neg° …
TP
T’
Wh-‐word Topic Subj
V-‐fin Conj
NegaCon
(Subj)
T° [Tense]
• The Tree-‐Pruning Hypothesis (TPH) (Friedmann & Grodzinsky 1997; Friedmann 2001) – Agramma-c aphasic pa-ents produce trees that are intact up to T° and pruned
from this node and up. – In less severe cases TP is also intact while CP is impaired.
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Complexity and training in agramma-sm
• The Complexity Account of Treatment Efficacy (CATE) – (Thompson & Shapiro 2007)
– “Training complex structures results in generaliza-on to less complex structures when untreated structures encompass processes relevant to (i.e., are in a subset rela-on to) treated ones”
• …but not vice versa
Kompleksitetstyper
# proposi-ons
# embeddings
(Non)-‐canonical word order
Distance btw. crucial elements
Structural posi-on (high > low)
Complexity & word order
1 Wh-‐move. (“forfelt”/Spec-‐CP) (Rela-ve, wh-‐ques-on, Topic, …)
2 NP-‐move. (Subj/Spec-‐TP) (Raising, Passive)
Com-‐plex
Sim-‐plex
Wh-‐ move
NP-‐ move
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Complexity and training in agramma-sm
• Training the (right type of) complex structure rather than the simplex type is faster and more efficient than vice versa.
• It also works with Specific Language Impairment (SLI) (Levy & Friedmann 2009)
OBJ-‐relaCve I know song
[that she is singing __].
OBJ-‐cleV It is the song
[that she is singing __].
OBJ-‐quesCon What is she singing __?
Raising Peter appears
[__ to ignore the problem].
Passive The problem is ignored (by Peter).
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Nega-on
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Polarity and entailment
• Affirma-ve/Posi-ve (POS) involves more general seman-c ‘structure’ than Nega-ve (NEG):
– POS is upward-‐entailing • (from subset to superset / from specific to general)
– NEG is downward entailing • (from superset to subset / from general to specific)
POSITIVE NEGATIVE
I would like to buy some apples. I would not like to buy some apples.
UP I would like to buy some fruit. I would not like to buy some fruit.
DOWN I would like to buy some Granny Smith. I would not like to buy some Granny Smith.
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Polarity and structure
• NEG involves more syntac-c structure than POS (Haegeman 1995, Christensen 2005)
AdvP not
Neg°
NegP
Neg’
VP join the club
I° will
I’ DP he
IP Cº because
CP
VP join the club
I° will
I’ DP he
IP C° because
CP
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Polarity and structure • Nega-ve islands (Ross 1984, Cinque 1990):
It’s amazing that you are (not) more clever than me already.
It’s amazing how clever you are ___ already. *It’s amazing how clever you are not ___ already. *It’s amazing how clever you aren’t ___ already.
• The Germanic what-‐for split (Vikner 1995:22)
POSITIVE NEGATIVE
Hvad for studerende har du inviteret ____? What for students have you invited? “Which students have you invited?”
Hvad for studerende har du ikke inviteret ____? What for students have you not invited? “Which students haven’t you invited?”
(?)Hvad har du inviteret ____ for studerende? What have you invited for students?
*Hvad har du ikke inviteret ____ for studerende? What have you not invited for students?
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Polarity and interpreta-on
• NEG is more difficult than POS (Carpenter & Just 1975, Carpenter et al. 1999, Chase & Clark 1972, Hasegawa et al. 2002)
– Requires more response -me – Induces more errors
• NEG is ini-ally interpreted as POS (Hasson & Glucksberg 2006; see also Carpenter & Just 1975, Chase & Clark 1972)
– Both POS and NEG prime POS-‐related words up to ~1000 ms.
My lawyer was a shark POS-‐related: Vicious My lawyer wasn’t a shark POS-‐related: Vicious NEG-‐related: Gentle
NEG = NEG [POS]
POS POS
NEG NEG
SOA = 0-‐1000 ms.
POS POS
NEG NEG
SOA > 0-‐1000 ms.
SOA = S-mulus Onset Asynchrony
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Polarity and interpreta-on • The two-‐step model (Kaup et al. 2006)
– A door that is not open is, eventually, mentally closed • Sentence-‐to-‐picture matching. Read S SOA Name Pict [Match/Mismatch] • A�er 750 ms: Match effect (RT x Match) for AFF but not NEG a�er 750 ms. • A�er 1500 ms: Match effect for NEG but not AFF.
Nega-ve sentence: The door is not open
Representa-on 1: Negated state of affairs
Representa-on 2: Actual state of affairs
Affirma-ve sentence: The door is open
Representa-on 1: Actual state of affairs
SOA (Time)
0 ms 750 ms 1500 ms
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fMRI and polarity • NEG: Increased syntac-c complexity
– increased ac-va-on in le� premotor cortex (BA 6) (also found by Hasegawa et al. 2002) – BA 6 is involved in (non-‐motor) rule-‐based computa-on (Hanakawa et al. 2002) – Note: No effect in Broca’s area.
• AFF: Entailment from sub-‐ to superset – Increased ac-va-on in right SMG (inf. Par., BA 40) – SMG is involved in lexical retrieval and (high level hierarchical) mul-modal associa-on (Fuster
2003)
Neg > Pos Pos > Neg Pos > Neg
(Christensen 2009, J Neurolinguis-cs, 21.2) 16
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AFF > NEG • AFF is default
– NEG is ini-ally interpreted as AFF – NEG is more difficult – NEG has more syntac-c structure
• Arguably, certain brain areas has a default level of ac-va-on (e.g. Raichle et al. 2001) – ‘Ac-ve’ tasks induce decreased local
ac-va-on as the “default mode” is temporally suspended.
• AFF > NEG shows “default mode” ac-va-on. – Anterior cingulate cortex (ACC)
Raichle et al. (2001: 681)
CP
TP
NegP
VP
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Syntac-c movement
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Cyclic deriva-on and structure-‐to-‐meaning mapping
The proposi-on: Pragma-c/Discourse related info (Illocu-onary Force, Topic, Focus)
Subject-‐Predicate (”Nexus”), Tense, Aspect, Voice, Polarity
The predica-on: Thema-c-‐structure, “Who did what to whom”
Copy/Move
CP
IP
VP
Copy/Move
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ARTIC
LEIN
PRESS
Table 1Summary of other fMRI studies
Targetdomain
Movement contrast Activation clusters
IFG/ant. ins VPrCG (BA6) Heschl’s(BA41/42)
pSTG Dorsal PrFG(BA6/8)
Ant. cing.(BA24/32)
CP Obj. rel4emb. decl. L — — L+R — —(Ben-Shachar et al., 2003)Wh4yes/no L L — L+R — —(Ben-Shachar et al., 2004)Topic4subj. Initial L L L L+R — —(Ben-Shachar et al., 2004)Topic4 re-serial. L L — L X X(Dogil et al., 2002)‘‘Long’’4‘‘short subj.’’ (scramblingabove subj.)
L+R — — L+R — —
(Fiebach et al., 2005)Subj–IO4IO–Subj (scrambling abovesubj.)
L+R — — — — —
(Grewe et al., 2005)Double obj. scrambling L — — — — —(Grewe et al., 2005)‘‘Easy’’4‘‘difficult’’ (scrambling abovesubj.)
L+R L — L — X
(Roder et al., 2002)
IP ‘‘Long’’4‘‘short obj.’’ (scramblingbelow subj.)
— — — — — —
(Fiebach et al., 2005)Pronominal scrambling — — — — — —(Grewe et al., 2005)
VP Dative shift R R — — — —(Ben-Shachar et al., 2004)‘‘Semantic’’4‘‘nonsemantic’’ R — — — — —(Roder et al., 2002)
IFG, inferior frontal gyrus; ant. ins., anterior insula; vPrCG, ventral precentral gyrus; Heschl’s, Heschl’s gyrus; pSTG, posterior superior temporal gyrus; PrFG,prefrontal gyrus; ant. cing., anterior cingulate gyrus; L, left, R, right; X, medial.
K.R.Christensen
/Journal
ofNeurolinguistics
21(2008)
73–103
81
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fMRI and syntac-c movement • Two types of movement, two different targets
(Christensen 2005, 2008)
– Hv-‐flytning Har manden ikke fanget nogen fisk? Hvilke fisk har manden ikke fanget ________
– Neg-‐ShiW Manden har ikke fanget nogen fisk. Manden har ingen fisk fanget ________.
IP
NegP
CP
VP ingen
Hv IP
NegP
CP
VP ikke
(Christensen 2008, J Neurolinguis-cs 21.2) 21
fMRI and syntac-c movement • Movement to CP Broca’s area
– Wh-‐ques-ons, rela-ve clauses, topicaliza-ons, “long” scrambling – ”ac-va-on of the le� BA 44i is modulated parametrically as a func-on of the
number of permuta-on opera-ons that need to be reconstructed.” (Friederici et al. 2006:1715)
– Cf. That these types are impaired in agramma-sm
• Movement to TP no Broca-‐effect – ”Short” scrambling, passiviza-on (!) (Yokoyama et al. 2007), Neg-‐Shi� – Cf. that nega-on seems to be rela-vely intact in agramma-sm (Hagiwara 1995,
Lonzi & Luzza� 1993) -‐ in spite of the level of complexity
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On nega-on and agramma-sm • Bas-aanse et al. (2002): Nega-on is impaired in languages where verb
movement and nega-on interact. – NEG clauses > AFF – Spanish (cli-c neg.) & English (do-‐support) > Dutch & Norwegian (V2) – Errors: Senten-al nega-on “cons-tuent nega-on”
• However… – May in part account for English and Norwegian but not for Dutch and Spanish
(p. 259) – Is it really cons-tuent (narrow scope) nega-on they produce? – At least nega-on is produced, not omiPed
– Target: The boy does not read the book – Produced: The boy does read not the book
The boy reads not the book
• Maybe placing the verb is the problem
The boy does not read(s) the book
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The Domain Hypothesis The proposi-on: Pragma-c/Discourse related info (Illocu-onary Force, Topic, Focus)
Subject-‐Predicate (EPP/”Nexus”), Tense, Aspect, Voice, Polarity
The predica-on: Thema-c structure
CP
IP
VP
Le� inferior frontal
(and more)
(Le� anterior temporal BA21/38)
“The effect of syntac-c movement in terms of neural ac-va-on is dependent on the target domain of the movement in ques-on.” (Christensen 2008:76) 24
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Crossed mapping
• Animacy (Grewe et al. 2006) – ANIMATE >> INANIMATE Dann wurde [O-‐A dem Arzt] [S-‐I der Mantel] gestohlen.
Dann wurde [S-‐I der Mantel] [O-‐A dem Arzt] gestohlen.
• Referen-ality (Bornkessel-‐Schlesewsky et al. 2009) – REFERENTIAL (name) >> NON-‐REFERENTIAL (bare plural) [S-‐R Peter] applauds [O-‐N authors].
[S-‐N Authors] applaud [O-‐R Peter]. *Ref>>Nref
[O-‐R Peter], [S-‐N authors] applaud. *Subj>>Obj
[O-‐N Authors], [S-‐R Peter] applauds. *Ref>>Nref, *Subj>>Obj
OASI SIOA OASA SAOA
SRON SNOR ORSN ONSR
Inanim >> Anim
Non-‐ref >> Ref
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Anomaly
World knowl. & sem. anom.
(Hagoort et al. 2004)
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Garden paths & dead ends
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Global structural ambiguity • Why do you think she leW?
– “Because someone who saw her leave told me.” – “Because she was bored.”
• He kissed a woman in a pink dress – kissed [a woman [in a pink dress]] – [kissed a woman] [in a pink dress]
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Unproblema-c local structural ambiguity
• Jack knew the girl. • Jack knew the girl loved Rex. • Jack knew that the girl loved Rex.
DP
Jack
T’
TP
T°
V°
knew
DP
the girl
VP
Object
Subject
Clausal Object
DP
Jack
T’
TP
T°
V°
knew
CP
VP
DP
the girl
T’
TP
T°
V°
loved
DP
Rex
VP
C°
(that)
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Garden paths • Garden path (GP) sentences:
– Local ambiguity – Preferred reading leading to
ungramma-cality – Reanalysis is very difficult or impossible
• The coZon shirts are made from comes from Arizona.
• Fat people eat accumulates.
• GPs increases ac-va-on in – Broca’s area and post. temp. cortex
(e.g., Fiebach et al. 2004) – and premotor cortex (BA 6) (Uchiyama
et al. 2008)
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fMRI, garden paths, & dead ends
• GP: The toughest men know love soap too. • NGP: The toughest men know and love soap too.
• DE: More people have been to Paris than I have. • CCC: More people have been to Paris than to Aarhus.
Christensen (2010) Brain and CogniDon 73.1 31
fMRI, garden paths, & dead ends
Reanalysis (GP)
Christensen (2010) Brain and CogniDon 73.1
DP
NP
AdjP NP
Nº mænd men
Adjº sejeste toughest
Dº De The
CP
C’
Cº kender know
??? bruger
use
DP
NP
NP
Nº sejeste toughest
Dº De The
CP
C’
Cº bruger
use CP
Cº (som) (that)
C’
mænd kender men know
IP
også sæbe also soap
DP
CP Flere folk More people
CP
C’
har været i Paris have been to Paris
IP
VP
har været i Køge have been to Køge
end than
(der)
DP
CP Flere folk More people
CP
C’
har været i Paris have been to Paris
CP
CP
end (...) i Køge than to Køge
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GP DE NGP CCC
Legend
L-BA 21 R-BA 9
R-BA 4 L-BA 6
L-BA 6
L-BA 44 L-BA 45
*** **
*** (*) *** *
*** n.s. *** **
*** n.s. *** *
Figure 7
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Reconstruc-on (CCC)
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Summary / Conclusions
• Broca’s area is neither the “speech centre”, nor the “syntax centre” – though clearly crucial to both.
• Wernicke’s area is neither the “comprehension” centre, nor the “seman-cs” centre – though clearly crucial to both.
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Summary / Conclusions
• Structure-‐dependent computa-on involves a distributed cor-cal network – Including Broca’s, Wernicke’s, premotor
• The ac-va-on in the “brain bark”, cortex, depends on the nature of the syntac-c tree.
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References Bornkessel-‐Schlesewsky, I., Schlesewsky, M., & von Cramon, Y. (2009) Word order and Broca’s region:
Evidence for a supra-‐syntac-c perspec-ve. Brain and Language 111, 125-‐139. Carpenter, P.A., & Just, M.A. (1975). Sentence comprehension: A psycholinguis-c processing model of
verifica-on. Psychological Review, 82, 45-‐73. Carpenter, P.A., Just, M.A., Keller, T.A., Eddy, W.F., & Thulborn, K.R. (1999). Time course of fMRI-‐
ac-va-on in language and spa-al networks during sentence comprehension. NeuroImage, 10, 216-‐224.
Chase, W.G., & Clark, H.H. (1972). Mental opera-ons in the comparison of sentences and pictures. In L. Gregg (Ed.), CogniDon in Learning and Memory, New York: Wiley.
Christensen, K.R. (2005). Interfaces: NegaDon -‐ Syntax -‐ Brain. PhD disserta-on, Department of English, University of Aarhus.
Christensen, K.R. (2008) Interfaces, syntac-c movement, and neural ac-va-on: A new perspec-ve on the implementa-on of language in the brain. Journal of NeurolinguisDcs 21.2, 73-‐103.
Christensen, K.R. (2009) Nega-ve and affirma-ve sentences increase ac-va-on in different areas in the Brain. Journal of NeurolinguisDcs, 21.2, 73-‐103.
Christensen, K.R. (2010) Syntac-c Reconstruc-on and Reanalysis, Seman-c Dead Ends, and Prefrontal Cortex', Brain and CogniDon 73.1, 41-‐50.
35
References Cinque, G. (1990) Types of A-‐bar-‐Dependencies. Cambridge, Mass.: MIT Press. Fiebach, C.J., Vos, S.H., & Friederici, A. (2004) Neural Correlates of Ambiguity in Sentence
Comprehension for Low and High Span readers. Journal of CogniDve Neuroscience 16.9, 1562-‐1575. Friederici. A.D., C.J. Fiebach, M. Schlesewsky, I. Bornkessel & D.Y. von Cramon (2006) Processing
Linguis-c Complexity and Gramma-cality in the Le� Frontal Cortex. Cerebral Cortex 16.12, 1709-‐1717.
Friedmann, N. (2001) Agramma-sm and the Psychological Reality of the Syntac-c Tree. Journal of PsycholinguisDc Research 30.1, 71-‐90.
Friedmann, N., & Grodzinsky, Y. (1997) Tense and agreement in agramma-c produc-on: Pruning the syntac-c tree. Brain and Language 56, 397–425.
Fuster, J.M. (2003) Cortex and Mind. Unifying CogniDon, Oxford: Oxford University Press. Grewe, T., Bornkessel, I., Zysset, S., Wiese, R., von Cramon, D.Y., & Schlesewsky, M. (2006). Linguis-c
prominence and Broca’s area: The influence of animacy as a lineariza-on principle. NeuroImage, 32, 1395-‐1402.
Grodzinsky, Y. (2000) The neurology of syntax: language use without Broca's area. Behavioral and Brain Sciences 23.1, 1-‐71.
Grodzinsky, Y., Wexler, K., Chien, Y.-‐C., Marakovitz, S., & Solomon, J. (1993) The breakdown of binding rela-ons. Brain and Language 45, 396-‐422.
36
9/16/10
19
References Haegeman, L. (1995). The Syntax of NegaDon, Cambridge: Cambridge University Press. Hagiwara, H. (1995) The breakdown of func-onal categories and the economy of deriva-on. Brain and
Language 50, 92-‐116. Hagoort, P., Hald, L., Bas-aansen, M., & Petersson, K.M. (2004) Integra-on of word meaning and world
knowledge in language comprehension. Science 304, 438-‐441. Hanakawa, T., Honda, M., Sawamoto, N., Okada, T., Yonekura, Y., Fukuyama, H., & Shibasaki, H. (2002).
The Role of Rostral Brodmann Area 6 in Mental-‐opera-on Tasks: an Integra-ve Neuroimaging Approach. Cerebral Cortex, 12, 1157-‐1170.
Hasegawa, M., Carpenter, P.A., & Just, M.A. (2002). An fMRI study of bilingual sentence comprehension and workload. NeuroImage, 15, 647-‐660.
Hasson, U., & Glucksberg, S. (2006). Does understanding nega-on entail affirma-on? An examina-on of negated metaphors. Journal of PragmaDcs, 38.7, 1015-‐1032.
Kaup, B., Lüdtke, J., & Zwaan, R.A. (2006) Processing negated sentences with contradictory predicates: Is a door that is not open mentally closed? Journal of PragmaDcs 38.7, 1033-‐1050.
Levy, H., & Friedmann, N. (2009) Treatment of syntac-c movement in syntac-c SLI: A case study. First Language 29.1, 15-‐50.
Lonzi, L. & C. Luzza� (1993) Relevance of Adverb Distribu-on for the Analysis of Sentence Representa-on in Agramma-c Pa-ents. Brain and Language 45.3, 306-‐317.
37
References Pinker, S. (1994) The Language InsDnct, London: Penguin. Raichle, M.E., MacLeod, A.M., Snyder, A.Z., Powers, W.J., Gusnard, D.A., & Shulman,
G.L. (2001). A default mode of brain func-on. PNAS, 98.2, 676–682. Ross, J. (1984) Inner Islands. Proceedings of Berkeley LinguisDcs Society 10, 258-‐265. Saddy, J.D. (1995) Variables and Events in the Syntax of Agramma-c Speech. Brain and
Language 50, 135-‐150. Thompson, C.K., & Shapiro, L.P. (2007) Complexity in Treatment of Syntac-c Deficits.
American Journal of Speech and Language Pathology 16.1, 30-‐42. Uchiyama, Y., Toyoda, H., Honda, M., Yoshida, H., Kochiyama, T., Ebe, K., & Sadato, N.
(2008) Func-onal segrega-on of the inferior frontal gyrus for syntac-c processes: A func-onal magne-c-‐resonance imaging study. Neuroscience Research 61, 309-‐318.
Vikner, S. (1995) Verb Movement and Exple-ve Subjects in the Germanic Languages, New York: Oxford University Press.
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