Presentation on theme: "Netherlands Graduate School of Linguistics LOT Summer School 2006 Issues in the biology and evolution of language Massimo Piattelli-Palmarini University."— Presentation transcript:
Netherlands Graduate School of Linguistics LOT Summer School 2006 Issues in the biology and evolution of language Massimo Piattelli-Palmarini University of Arizona Session 3 (June 14) Loss of speech and two interesting hypotheses
LOT Summer 2006Loss of speech2 Some ancient history n Along many centuries, physicians and common people had observed cases in which a person had suffered some loss of speech. n The most ancient (indirect) testimony is to be found in the Bible (in the Ecclesiastes) n “And if I am found to have forgotten thy name, oh Sacred Jerusalem, may my right arm remain limping along my body and my tongue remain glued to the palate”.
LOT Summer 2006Loss of speech3 This association cannot have been invented n In fact, severe damage to the left hemisphere, indeed, typically produces the paralysis of the right arm, and loss of speech. n This is called, in modern terminology, “global aphasia” n It is the most severe form of loss of speech. n We will see in a moment less severe, more specific syndromes.
LOT Summer 2006Loss of speech4 Further evidence n The cognitive neuropsychologist John Marshall of Oxford has collected a large sample of historical documents referring to specific “modular” cognitive deficits. n Personal letters (incidentally) describing specific symptoms n Medical records n Military chronicles n Novels, poems, plays etc. n From the ancient Roman times to the 19th. Century
LOT Summer 2006Loss of speech5 An interesting consideration n Ample evidence of subtle and specific cognitive deficits has been commonly available for centuries n YET n The very idea of the modularity of mind is barely 25 years old n And it still meets strong resistance. n No one was “ready” to see it. n Speech impairments have been a very important domain
LOT Summer 2006Loss of speech6 A revealing synthesis (Russell A. Poldrack, UCLA, 2006) n 749 published papers, 3222 comparisons (from the BrainMap database) TICS Vol10 (2) February 2006, pp.61-62 Language study Not language study n Activated166199 n Not activated703 2154 n Jeffreys & Poldrack Bayesian factor f: n posterior odds/prior odds n 1 < f < 3 weak evidence n 3 < f <10 moderate evidence n 10 < f strong evidence n Here, for the reverse inference, it is 2.3
The standard “textbook” picture of aphasia Before, approximately, 1970 For a concise review, see Edgar B. Zurif Brain regions of relevance to syntactic processing. (Chapter 13) in Volume 2 of An Invitation to Cognitive Science Second Edition (D. N. Osherson, Editor) MIT Press 1995
LOT Summer 2006Loss of speech8 Paul Broca (1824 -1880) n In a series of papers published between 1861 and 1866 employing the clinico- pathological correlation technique to analyze a loss of speech (aphémie), Broca persuaded a majority of his colleagues that there was a relatively circumscribed center, located in the posterior and inferior convolutions of the left frontal lobe, that was responsible for speech (langage articulé).
LOT Summer 2006Loss of speech9 In a memorable meeting in 1862 he demonstrated the brain lesion of his first patient (Tan) who had suffered from aphémie (renamed aphasia later by Armand Trousseau (1801-1867)). Broca concluded that the integrity of the left frontal convolution was responsible and necessary for articular speech. David Ferrin (1843-1928) is responsible for naming this region "Broca’s convolution- the motor speech area."
LOT Summer 2006Loss of speech10 Brain of patient with motor aphasia (the famous “Tan”) studied by Broca is preserved uncut. The damaged area receives its blood from the left middle cerebral artery.
LOT Summer 2006Loss of speech11 Notice that it extends beyond the (now canonical) Broca’s area showing lesions of the underlying insula and the white matter (as it is often the case in such patients) (See Nina Dronker’s comment in BBS 2000)
LOT Summer 2006Loss of speech12 Broca’s famous patient (“Tan” -1861), after a stroke, had completely lost the ability to speak. The patient could apparently understand language, but the only syllable he could produce was "tan", over and over again. Broca referred to this patient as “Tan”. After Tan's death, Broca performed an autopsy and determined the site of the stroke.
LOT Summer 2006Loss of speech13 The “foot” of the 3rd gyral convolution of the left frontal lobe
LOT Summer 2006Loss of speech14 Early polemics n Pierre Flourens (1794-1867), Broca’s distiguished colleague (whom we “met” yesterday as a discoverer of the cerebellar functions) defied Broca’s conclusions n Damage to other regions (allegedly) had similar effects on speech n (Strangely) he maintained that the superior functions cannot be “localized” in one precise cerebral region.
LOT Summer 2006Loss of speech15 Classical description of Broca's aphasia n A person that suffers a lesion to that area understands language, communicates nonverbally, and writes, if not also paralyzed, but cannot articulate or speak fluently. (A sudden drop in fluency may, in fact, signal an impending stroke).
LOT Summer 2006Loss of speech16 Broca's aphasia: The clinical textbook description n This is a form of aphasia in which speech output is severely reduced and is limited mainly to short utterances, of less than four words. n Vocabulary access is limited in persons with Broca's aphasia, and their formation of sounds is often laborious and clumsy. n The person may understand speech relatively well and be able to read, but be limited in writing. n Broca's aphasia is often referred to as a 'non- fluent aphasia' because of the halting and effortful quality of speech.
LOT Summer 2006Loss of speech18 Brodmann areas Frontal Parietal Occipital Temporal
LOT Summer 2006Loss of speech19 Brodmann areas 44 & 45: Broca’s area Frontal Parietal Occipital Temporal Spoken language production (motor component) Brodmann area 45 is called the “triangular portion”.
LOT Summer 2006Loss of speech20 Brodmann areas 22 (Wernicke’s area) and 41 & 42: Herschl’s gyri Frontal Parietal Occipital Temporal Spoken language comprehension
LOT Summer 2006Loss of speech21 Brodmann areas 39 and 37 Frontal Parietal Occipital Temporal Written language perception All in all, language is said to reside in “peri-Sylvian areas” Visual assoc areas Sylvian fissure or “lateral sulcus”
LOT Summer 2006Loss of speech22 Wernicke’s Aphasia n It is characterized not by apparent loss of fluency but by absence of meaning in what the person says. n The words don't add up to informative sentences; or the person may have problems naming familiar objects, and call a cup an ashtray, for instance, or be unable to name a loved one.
LOT Summer 2006Loss of speech23 Wernicke’s Aphasics n These patients could not understand language, spoken or written, but could apparently produce copious flowing speech. n Their speech, however, made absolutely no sense. n Subjects and verbs would be strung together in a seemingly grammatical order, like fragments of real sentences, but the sentences seemed to bear little relation to what the patient was trying to express. n Presumably the patients could not understand what came out of their own mouths.
LOT Summer 2006Loss of speech24 Conduction aphasia n Broca's and Wernicke's speech areas intercommunicate via a thick arching bundle (called the arcuate fasciculus or bundle). n When damage to this pathway disconnects the two speech areas, language fluency and comprehension are not affected; n However, the sufferer cannot repeat newly presented phrases.
LOT Summer 2006Loss of speech25 Perisylvian language networks of the human brain (Catani, et al., 2005) n Next slides adapted from those of Katrina Nichols (University of Arizona) n Damage to arcuate fasciculus (white matter tract) connecting Broca’s and Wernicke’s areas results in conduction aphasia (intact comprehension and production but inability to repeat what heard) Catani, M., Jones, D. K., and Ffytche, D. H. (2005). Perisylvian language networks of the human brain Annals of Neurology, 57, 8 - 16.
LOT Summer 2006Loss of speech26 Perisylvian language networks of the human brain (Catani, et al., 2005) n Conduction aphasics (temporoparietal lesions) are a heterogeneous group in terms of impairment (some more Broca-like, some Wernicke-like) suggesting arcuate fasciculus may not be the only underlying structure n Authors were interested searching for other possible perisylvian (temporoparietal areas) language networks to explain data n Used in vivo diffusion tensor magnetic resonance imaging tractography (to extrapolate white matter trajectories)
LOT Summer 2006Loss of speech27 Perisylvian language networks of the human brain (Catani, et al., 2005) n Newly discovered but evolutionarily older structure in addition to the classical arcuate fasciculus u parallel and lateral to classical arcuate fasciculus u Connects “Geschwind’s territory” (inferior parietal cortex) to classical language areas (Broca’s and Wernicke’s areas) u Rudimentary form exists in the brain of other primates (macaque)
LOT Summer 2006Loss of speech28 Perisylvian language networks of the human brain (Catani, et al., 2005) Arcuate fasciculus (long segment; medial) and “new” network (anterior segment and posterior segment)
LOT Summer 2006Loss of speech29 Perisylvian language networks of the human brain (Catani, et al., 2005) n Corroborates neuropsychological evidence for different subtypes of conduction aphasia u Classical conduction aphasia – long segment lesion; failure in automatic repetition u Transcortical aphasia – anterior segment lesion; failure to vocalize semantic content u Sensory aphasia – posterior segment lesion; failure of auditory semantic comprehension
LOT Summer 2006Loss of speech30 Perisylvian language networks of the human brain (Catani, et al., 2005) n “The fact that these pathways [ the ones including the anterior and posterior segments] appear to exist – in more rudimentary forms – in the brains of monkeys may also have bearing on the search for the evolutionary origins of language. ‘These data suggest that language evolved, in part, from changes in pre-existing networks, not through the appearance of new brain structures,’ said Catani.” u American Neurological Association press release, 2006 n This is in line with non-drastic, piecemeal changes occurring in evolution, not complicated overhauls of structures
LOT Summer 2006Loss of speech31 Global aphasia n This is the most severe form of aphasia, and is applied to patients who can produce few recognizable words and understand little or no spoken language. n Global aphasics can neither read nor write. n Global aphasia may often be seen immediately after the patient has suffered a stroke and it may rapidly improve if the damage has not been too extensive. n However, with greater brain damage, severe and lasting disability may result.
LOT Summer 2006Loss of speech32 Mixed non-fluent aphasia n This term is applied to patients who have sparse and effortful speech, resembling severe Broca's aphasia. n However, unlike persons with Broca's aphasia, they remain limited in their comprehension of speech and do not read or write beyond an elementary level.
LOT Summer 2006Loss of speech33 Anomic aphasia n This term is applied to persons who are left with a persistent inability to supply the words for the very things they want to talk about - particularly the significant nouns and verbs. n As a result, their speech, while fluent in grammatical form and output, is full of vague circumlocutions and expressions of frustration. n They understand speech well, and in most cases, read adequately. n Difficulty finding words is as evident in writing as in speech. n Mostly associated with damage to the angular gyrus
LOT Summer 2006Loss of speech34 Fisher, S. E., & Marcus, G. F. (2006). The eloquent ape: genes, brains and the evolution of language. Nature Reviews Genetics, Vol. 7 (January), pp. 9-20.
LOT Summer 2006Loss of speech35 The study of aphasia comes of age n Edgar B. Zurif and Alfonso Caramazza, since the mid-Seventies, characterize agrammatic aphasia n Gabriele Miceli and Alfonso Caramazza draw close comparisons between agrammatic aphasics in English and in Italian n David Caplan (MGH and Harvard Med. Sch.) and collaborators explore in detail “disorders of syntactic comprehension” n The traditional classification collapses: Wernicke aphasics also show syntactic impairments, while Broca aphasics also show semantic impairments. n The “single case” approach is proposed, raising serious objections n Yoseph Grodzinski (ever since 1984) proposes the TDH (trace deletion hypothesis) (see infra)
LOT Summer 2006Loss of speech36 The single-case method n Specific impairments ascertained in one patient are explained by certain functional disconnections n Normal performance in the same patient on other cognitive tasks is explained by other connections being intact n Flow charts are then constructed n The legitimacy (or the non-legitimacy) of postulating processing units and connections is put to test n The most cogent test is one of the “necessity” of a certain node, or connection, for a given cognitive task
LOT Summer 2006Loss of speech37 Typical dissociations n Some patients show an impairment with nouns (they use thing, stuff, not, say, cake, chair, etc.), but not with verbs n Other patients show an impairment with verbs (they omit them altogether, or pause, or just use do, get), but not with nouns n Word-endings can be affected n Or word-beginnings n Only in writing, or only in speech (modality- specific deficits) n And many more kinds of dissociations n Different brain areas are correspondingly affected (verbs frontal and fronto-parietal, nouns temporal and fronto-temporal)
LOT Summer 2006Loss of speech38 From Rapp & Caramazza, 1998 Accurate and complete oral description, but the verb is omitted in writing. Inverse symmetric deficits have also been reported. A modality-specific deficit like this one cannot be “semantic”
LOT Summer 2006Loss of speech39 Agrammatism (left frontal lesions) n Morphosyntactic processing is impaired in production (inflection and agreement) regardless of the lexical class of the items (verbs, nouns, adjectives), functional elements are omitted in zero-morphology languages, inter-substituted in non-zero-morphology languages. n Goodglass and Berko, 1960; Goodglass, 1968; Berndt and Caramazza, 1980. n The differentiation between the morphological, lexical, syntactic and semantic components, and the corresponding brain lesions, is often debated (see Caramazza and Shapiro, in Jenkins’s volume) n In later years, (refined)-EEG, PET, fMRI, MEG and rTMS (repeated Transcranial Magnetic Stimulation) add new data. The correspondence with brain lesions is not always neat, but approximately satisfactory.
LOT Summer 2006Loss of speech40 Lesions versus imaging n Participation of a brain region in a task is not the same as the localization of that task in that region. n In a nutshell: Lesions show whether a given brain region is “necessary” for that task n Imaging shows that the region is (strictly, and selectively, in some cases) recruited for that task. n rTMS (is rather a suppression than a stimulation) is closer to lesions, because it generates a “temporary virtual lesion”
LOT Summer 2006Loss of speech41 Zooming onto Broca’s area lesions n Caramazza and Zurif (1976) challenge the (then) prevailing view that comprehension is unaffected in Broca’s aphasics n Semantically non-reversible sentences n The apple that the boy is eating is red. n Versus semantically reversible sentences n The boy that the girl is chasing is tall. n Good to perfect performance by Broca’s aphasics on the first, poor on the second. n Hypothesis: A common mechanism is affected in understanding and in production n Agrammatic production goes with “asyntactic comprehension” n But patients not obeying this generalization were soon discovered.
LOT Summer 2006Loss of speech42 Rectifying the claim: n Production and comprehension may not exploit a common mechanism n Clinical categories (such as Broca’s aphasia) do “not uniquely determine the nature of the underlying deficit in the patient included in those categories.” (Caramazza et al. 2001) n Notice: The reversible/irreversible character of the test sentences was lexical-semantic n But it could also be reinterpreted as “canonical” agent-theme order versus an inverse order. n This is what Grodzinsky emphasized, coming up with a new syntactic hypothesis: The TDH (Trace Deletion Hypothesis)
The Trace Deletion Hypothesis Let’s see it in the “pure” form, before we discuss the problems
LOT Summer 2006Loss of speech44 Broca’s aphasics have no problem understanding: n Basic syntactic trees and violations of basic phrase-structure rules n Lexical meanings and their interface with syntax (violations of sub-categorizations are easily detected by them) n Argument structure (when movement and traces are not involved) n (Full interpretation is unaffected) n Basic inter-sentential dependencies (relatives, subordinates etc. When no movement and traces are involved) n Case assignment (esp. in languages that have overt case, such as Serbo-Croat) n Binding and anaphoric relations (with some exceptions)
LOT Summer 2006Loss of speech45 Zooming onto Broca’s area lesions n Grodzinsky’s TDH 1 (Trace Deletion Hypothesis first version): Broca’s aphasics have an impairment in comprehension only when confronted with sentences that present movement and traces, but not otherwise. n A “particularly influential hypothesis” (said by an opponent: Alfonso Caramazza) n Methods: Picture selection task upon presentation of sentences, truth judgments, and detection of non-grammaticality n Reminder: They cannot “produce” such sentences (but see the tree-pruning hypothesis) n Above-chance (often 100%) correct performance signals absence of a comprehension impairment n Chance performance signals a comprehension impairment
LOT Summer 2006Loss of speech46 What’s being ruled out: n Generic “working memory” impairment n Generic “linking” impairment n Generic impairment with “inversions” (extending to non-linguistic domains, see Grodzinsky’s 2000 BBS paper) n Generic impairment with “complex” syntactic constructions of all kinds n A problem confined to lexical knowledge n And/or to “encyclopedic” knowledge n The spoon ate the table is understood perfectly, in spite of its semantic implausibility
LOT Summer 2006Loss of speech47 Typical data: Minimal pairs (AC=above chance, C=chance) n Active versus passive n The woman is chasing the man AC The man is chased by the woman C n Subject relative versus object relative n The woman who is chasing the man is tall AC The man that the woman is chasing is tall C n Subject-gap versus object-gap n Show me the woman who is chasing the man AC Show me the man who the woman is chasing C n Subject cleft versus object cleft n It is the woman that is chasing the man AC It is the man that the woman is chasing C
LOT Summer 2006Loss of speech48 Other data n No impairment with head-movement as such. n Grammaticality judgments are perfect for: n Could they have left town? n *Have they could leave town? n John did not sit. n *John sat not. n OK with full interpretation n Who did John see? n *Who did John see Joe? n *Mary ate the bread that I baked a cake. n OK with selectional restrictions on transitive complements and object deletion n The children sang. n *The children sang the ball over the fence. n *The children threw. n The children threw the ball over the fence.
LOT Summer 2006Loss of speech49 Refining the hypothesis n Broca’s area as “neural home to receptive mechanisms involved in the computation of the relation between transformationally moved phrasal constituents and their extraction sites” (Grodzinsky, 2000, BBS) n But those patients perform successfully in constructions that involve movement of the VP- internal subject to [Spec, IP] (Hickok, 1992) n A better hypothesis: -conflict n Somehow, the patient is receiving thematic information that both NPs in the sentence have the same -role, and that, therefore, any one of them can be matched to the agent and the patient argument in the sentence. n The performance is, thus, 50% (chance)
LOT Summer 2006Loss of speech50 Minimal pairs n Which man t touched Mary? AC n Which man did Mary touch t? C n The man who t is touching Mary is tall. AC n The man who Mary is touching t is tall. C n A non-grammatical strategy assigns the role of agent to the first NP, and that of patient (or theme) to the second (in English) n When this matches the grammatical (impaired) processing, all is OK n When it does not, a conflict arises, and performance is at chance level
LOT Summer 2006Loss of speech51 A specific hypothesis n The TDH hypothesis does not bear upon the mere syntactic “complexity” of the sentence n Nor upon the “first” versus “second” position of the NPs and the traces n Nor upon the “left” versus “right” position n It bears upon the standard position of -roles and arguments in the patient’s language, whatever that is. n In fact, in Chinese (an otherwise SVO language like English) the heads of the relative clauses follow the relative, contrary to English
LOT Summer 2006Loss of speech52 Minimal pairs in Chinese and English n The h index indicates the head of the relative clause n [t zhouei gou] de mau h hen da C chased dog that cat very big n [mau zhouei t] de gou h hen xiao AC cat chased that dog very small n The inverse is the case in English n The cat h that [t chased the dog] was very big AC n The dog h that [the cat chased t] was very big C n Mirror-image results: Agent/agent conflict in English, theme/theme conflict in Chinese n Similar results in Hebrew, Spanish, Korean and German (see Grodzinsky’s papers for biblio)
LOT Summer 2006Loss of speech53 Scrambling in Japanese: Minimal pairs n 2 possible configurations, with different results in Broca’s aphasics (Hagiwara and Caplan, 1990) n (a) Taro-ga Hanako-o nagutta AC Taro hit Hanako Subject Object Verb n (b) Hanako-o Taro-ga t nagutta C Object Subject t Verb n SOV is the basic order, while OStV is the “scrambled” (secondary) order (Hale, 1983; Saito, 1985; Miyagawa, 1997) n In (b) Hanako must c-command the VP, so it must have moved to adjoin a higher projection than that of the subject (Taro) n (See many details in the BBS paper)
LOT Summer 2006Loss of speech54 Scrambling in Japanese aphasics n Basic (unscrambled) actives and indirect passives are above chance n Derived (scrambled) actives and direct passives are at chance n This shows that it is not the passive construction as such that is affected n (This has exasperated Caramazza) n The real discriminator is movement (and traces) n Not insensitivity to overt morphological “cues” of the passive construction (-en and the preposition by in English) n Nor semantic “plausibility” (as we saw)
LOT Summer 2006Loss of speech55 The -conflict hypothesis TDH 2 (2000) n Full interpretation is preserved (see previous data): A thematic role must be assigned to every NP in the sentence. n A non-syntactic linear order strategy is also applied (see Bever 1970, Bever and Townsend 2002, Jaeggli 1986) n (in English) n Whenever you identify one -role for one NP, then you assign the other -role to the other NP n When constituents are moved, the interpretation of traces becomes crucial n But the Broca’s aphasic cannot interpret traces, nor moved constituents. His/her syntactic representation is “traceless” n So he/she resorts to the linear order strategy n When the linear order matches the syntactic assignment, all is OK n When not, a conflict arises, and comprehension is at chance level
LOT Summer 2006Loss of speech56 The -conflict hypothesis n We have a partial thematic representation and a non- syntactic cognitive strategy (à la Bever et al.) that tries to compensate for the impotence of a “traceless” syntax n When the “theme” role is correctly assigned to the second NP in the sentence, then the agent role is correctly assigned to the first NP n Which man t touched Mary? AC n................................. Mary =theme (no mediation of the trace) n Therefore n Which man = agent (regardless of the trace) n But n Which man did Mary touch t? C n Mary =agent of the relative clause (no trace mediation) n Which man = agent in virtue of the linear strategy n Therefore conflict, and 50%-50% resolution of the conflict
LOT Summer 2006Loss of speech57 The -conflict hypothesis n There should also be cases of systematic inversion (that is, below chance performance) n In fact there are (Grodzinsky, 1995, 2000) n with psych verbs (admire, love, adore, fear, etc.) (Belletti and Rizzi, 1988; Pesetsky, 1995) n The syntactc subject is not really an “agent”, it’s rather an “experiencer”, and the “object” is really a “theme” n Normal assignment in yellow, Broca’s aphasic’s assignment in blue: n Theme Experiencer n [The girl] i was t’ j admired t i by [the boy] j n Agent Experiencer n No conflict here. The inversion is systematic n No problem with the active counterpart n The boy admired the girl
LOT Summer 2006Loss of speech58 Additional evidence for TDH: fMRI n With important caveats, it should be the case that normal subjects asked to perform on sentences with inverted traces show an activation of Broca’s area. n One has to tear this apart from other, generic, estimates of sentence complexity n Maintain sentence length, number of words, embeddings, functional to lexical categories ratio etc. constant n Let only the relevant parameters (number of arguments and movement, and the position of the traces) vary
LOT Summer 2006Loss of speech59 Minimal pairs n M. Ben-Shachar’s minimal pairs in Hebrew n Object relative clauses versus main verbs that take CP complements n ‘azarti la-yalda [Se-Rina pagSa t ba-gina] helped-I to-the-girl that-Rina met t in-the-garden I helped the girl [that Rina met t in the garden] n ‘amarti le-Rina [Se-ha-yalda yaSna ba-gina] told-I to-Rina that-the-girl slept in-the-garden I told Rina [that the girl slept in the garden] n Switch the verb (meet exchanged for sleep) and you have an ungrammatical counterpart for each sentence n The subjects were asked to make grammaticality judgments for each minimal pair
LOT Summer 2006Loss of speech60 Results: n More intense signal in the left inferior frontal gyrus (Broca’s area) for the sentences that involve movement and trace n In agreement with the data on Broca’s aphasics n Also Hershl’s gyri (Brodmann area 22) are activated bi-laterally (temporal lobes)
LOT Summer 2006Loss of speech61 From Ben-Schachar et al. (in Grodzinsky’s 2000 paper) RL
LOT Summer 2006Loss of speech62 Herschl’s gyrus Frontal Parietal Occipital Temporal Areas 22 are also activated bi-laterally. Syntax is not all in the left hemisphere
LOT Summer 2006Loss of speech63 Similar fMRI data for scrambling n Activation of the same areas (Broca’s left, and Herschl’s bilaterally) is observed for scrambled embedded double-object verbs in German (Röder et al, 2002) n Jetzt wird der Astronaut dem Forscher den Mond beschreiben Now will the astranaut [to] the scientist the moon describe n Jetzt wird dem Forscher den Mond der Astronaut t t beschreiben
LOT Summer 2006Loss of speech64 And for overlapping regions being activated by: n Embedded wh-questions versus yes/no questions n Object topicalized versus non-topicalized main clauses
LOT Summer 2006Loss of speech65 Additional data from psycholinguistics n Priming and gap-filling (see J. D. Fodor, D. Swinney et al, and Zurif’s chapter in Osherson) n Sentences heard over earphones n The man liked the tailor i with the British accent who (t) i claimed to know the queen. n Lexical probe (clothes and boat) flashed on a screen, alternatively in position 1 (pre-gap) and 2 (at the gap). Lexical decision time is attributed to re-activation of the tailor at the gap n The man liked the tailor i with the British accent 1 who 2 (t) i claimed to know the queen. n Broca’s aphasics manifest no difference at all n Normal subjects and Wernicke’s aphasics show a robust gap-filling effect.
LOT Summer 2006Loss of speech66 A virtuoso extension (see the paper) n Can fMRI data “decide” between competing syntactic hypotheses? n Data from location and intensity are needed n Location tells about same versus different computations n Intensity tells about effort (primary versus additional computations) n Double object constructions (Larson, 1988; versus Aoun and Li, 1989) n Data from fMRI on Hebrew stimuli (Ben- Schachar and Grodzinsky, 2002) n What type of movement (if any) is involved? n Which complement order (dative or double object) is derived, and which base-generated?
LOT Summer 2006Loss of speech67 Data on dative/double object n Dative-shift contrast versus topicalization contrast on minimal pairs in Hebrew n Activation of different brain regions would signal a difference in processing n Different relative intensity would signal greater effort (greater mental computation) for the construction that is not base-generated n There is a difference of activation for topicalization versus dative shift n The latter activates right frontal brain regions, different from those activated by topicalization n In these regions, activation is significantly higher for the double object than for the dative shift n In Hebrew, double object constructions appear, therefore, to be derived and not base- generated.
LOT Summer 2006Loss of speech68 Comments to Grodzinsky’s BBS target article n Other hypotheses can explain all the data n The data are mostly (all) wrong n Only parts of the hypothesis are correct n Issues with definitions, categorizations, anatomical localizations n Compatible with GB, but not minimalism, therefore minimalism is wrong n Better compatible with minimalism, rather than GB, therefore minimalism is right n The implications of the hypothesis are quite different n Checks with “better data” are suggested n Better confirming data are actually offered
LOT Summer 2006Loss of speech69 Comments to Grodzinsky’s BBS target article n Other conclusions should be derived from the data n Other kinds of data should be explored n The basic assumptions are flawed (modularity, specificity of language, the value of generative grammar, etc.) n This work has merits, in spite of specific problems n This work is basically flawed, in spite of its limited success n Accusations of neglect of other (falsifying) data
LOT Summer 2006Loss of speech70 Not everything that shines is gold n Caramazza, Capitani, Rey and Berndt (2001) Brain and Language, Vol. 76, pp.158-184 n Brandishing Popper’s criterion of falsifiability, n Produce additional data, and re-examine Grodzinsky’s own data, concluding that n There is a mixed bag of symptoms, in Broca’s aphasics, including instances of TDH, but a lot more, n And cases in which there is no evidence of DTH: “a number of distinct patterns in different patients”. n Their specific target is active vs passive and subject vs object relatives and clefts n A battle on quantifiers: “all” patients versus “most” patients, “necessarily” versus “possibly”
LOT Summer 2006Loss of speech71 Conflicting statistical analyses n Berndt et al. (1996) and Grodzinsky et al. (1999) reach different conclusions from the same data bank of patients (over 40 cases), on tests on passive versus active sentences. n Only 1/3rd of the patients confirm the pattern predicted by Grodzinsky’s TDH n Is the grouping of patients under the category “Broca’s aphasics” consistent? n Excruciating (to us) details follow as to the proper classification of patients, the proper methods of testing, and the right (as opposed to “creative”) kind of statistical analyses. n Over 83% correct is labelled “above chance”, 55% or lower is labelled “chance”
LOT Summer 2006Loss of speech72 The Caramazza et al.’s calculations (in essence) n If a population of patients (as it were) flips a coin to understand a “hard” sentence, we get a single-mode binomial distribution (a Gaussian) distributed around the mean 50% n But, if the population is not uniform for this task, and rather shows great individual variance for this task, then we have a multi-modal distribution, with important “tails” at the extremes. These must not be merged with the rest in the statistical analysis n They show that the distribution is, indeed, multi-modal n Broca’s aphasics do not constitute a homogenous population for the active/passive comprehension test.
LOT Summer 2006Loss of speech73 Caramazza et al.’s conclusions n Grodzinsky’s hypothesis is falsified n Even when one concedes the “corrections” suggested by Grodzinsky n The suggestion to re-classify bona fide Broca’s aphasics is an objectionable move, n (At least until new objective and rigorous criteria are provided) n Making the hypothesis un-falsifiable, and therefore un-scientific n Popper’s famous case of black swans is cited
LOT Summer 2006Loss of speech74 Grodzinsky’s reply: n Data on passives are indeed not neat (the case of Dutch). There is individual variation n Caramazza et al.’s claims would indeed be worrysome, if correct. n Critical re-analysis of the replication failures (test-design, patient diagnosis, test administration and statistical analysis) n In spite of inevitable (minor) individual differences in the lesions, the diagnosis of Broca’s aphasia is sufficiently consistent across languages, laboratories and groups. n A very large data set for the statistics has been assembled
LOT Summer 2006Loss of speech75 Statistical criteria n 77 patients tested on 2 groups of constructions n (1) ac-TDH Above chance (actives, subject relatives, subject questions, subject clefts) n (2) c-TDH chance (passives, scrambled actives - in German, Spanish, Hebrew and Korean-, object relatives, object questions, object clefts) n Number of patients showing c (40-70% correct) and, respectively, ac (over 80% correct) is plotted against percentage correct n The range of individual variation on c is much greater that than on ac n Mean around 50% for c, quasi-asymptote to 100% for ac
LOT Summer 2006Loss of speech76 From Y. Grodzinsky (in the Jenkins volume) The solid curve is indistinguishable from chance
LOT Summer 2006Loss of speech77 Is this one group of subjects? n The wide distribution of the c curve has suggested to Caramazza et al that we are dealing with a heterogeneous group of subjects n Grodzinsky and colleagues deny that this is the case n Essentially, they compute the numerical advantage represented by a bi-modal Gaussian, versus a uni-modal Gaussian n They conclude that there is no advantage (no better approximation to the data) to the bimodal n And conclude that we are indeed dealing with one homogeneous group of patients (one syndrome)
LOT Summer 2006Loss of speech78 A new development n Dan Drai and Yosef Grodzinsky A new empirical angle on the variability debate: Quantitative neurosyntactic analyses of a large data set from Broca’s Aphasia Brain and Language, Volume 96, Issue 2, February 2006, Pages 117- 128 n David Caplan, Gayle DeDe and Hiram Brownell Effects of syntactic features on sentence–picture matching in Broca’s aphasics: A reply to Drai and Grodzinksy (2005) DISCUSSION Brain and Language, Volume 96, Issue 2, February 2006, Pages 129-134 n The punch line: “Performance variation within a group of patients in itself does not preclude the existence of structure in their deficit. Thus in aphasia the data may present inter- patient variability, but the challenge for us is to try and discover commonalities at the group level in the face of this variability”.
LOT Summer 2006Loss of speech79 A new development n We have compiled a large data set of raw data of performance scores, and adopted a statistical methodology which gives a precise quantitative meaning to the question of the existence of a significant difference in performance — analyzed at the group level— between two types of sentences. Note that the approach is general and can be applied to any subject group, and to any categorization of the sentences. We did apply our method to performances of Broca’s aphasics, for whom we have different existing categorizations of sentences. n This method reveals a highly significant performance difference when the data are categorized by a syntactic principle (whether or not sentences contain a Transformational Movement relation); more traditional ones (Mood [active/passive], Sentence Complexity [high/low]) yield no contrast.
LOT Summer 2006Loss of speech80 What seems to be uncontroversial: n Language processing is modular n Different brain regions (mostly, but not exclusively, in the left cerebral hemisphere) are involved in different linguistic computations n Some regions are involved specifically in syntactic processing n Most Broca’s aphasics match the picture given by the Trace Deletion Hypothesis: n They have a specific impairment with infrasentential dependencies involving traces, when constituents have been extracted from the object (or theme) position n Data from lesions and data from imaging are comparable and approximately converging
LOT Summer 2006Loss of speech81 A new book that says it all: n Yosef Grodzinsky and Katrin Amunts Broca’s Region Oxford University Press (2006) n Proceedings of a conference, much re-worked and updated n With a new translation of Broca’s original paper and with other historical landmark papers.
LOT Summer 2006Loss of speech82 Broca’s Area Revisited A few cytoarchitectonic borders, e.g., between the somatosensory cortex and the primary motor cortex and between the primary and secondary visual areas, are obvious and can be clearly defined by pure visual inspection. For these borders, discrepancies between different observers are marginal. However, the cytoarchitecture of the vast majority of cytoarchitectonic areas does not differ this distinctly. Amunts, K., Schleicher, A., Buerger, U., Mohlberg, H., Uylings, H. B. M., & Zilles, K. (1999). Broca's region revisited: Cytoarchitecture and intersubject variability. The Journal of Comparative Neurology, 412, 319-341.
LOT Summer 2006Loss of speech83 Broca’s Area Revisited The observer-independent procedure introduced in this paper localizes the precise position of the border even in such cases because the definition of borders is based on single and significant peaks in the multivariate distance function. This procedure allows one to identify a transitional area as a distinct cytoarchitectonic unit with reproducibly definable borders. A similar statistical approach is widely used in functional imaging studies because clusters of activation are considered meaningful only if there are significant differences between signal and ‘‘noise’’. Amunts, K., Schleicher, A., Buerger, U., Mohlberg, H., Uylings, H. B. M., & Zilles, K. (1999). Broca's region revisited: Cytoarchitecture and intersubject variability. The Journal of Comparative Neurology, 412, 319-341.
LOT Summer 2006Loss of speech84 Broca’s Area Revisited The laminar distribution of cell densities was measured with an automated microscopic scanning procedure using an image analysis system (Schleicher and Zilles, 1990). The resulting gray level index (GLI) is a reliable measure of cell packing density in the cortex (Wree et al., 1982). Statistically significant changes in the laminar distribution of the GLI can be detected at the transition between two cytoarchitectonic areas but not within an homogeneous area (Schleicher et al., 1995, 1998). A procedure based on the detection of such changes in GLI has been shown to be sensitive for interhemispheric, ontogenetic, and areal differences (Zilles et al., 1986b; Schlaug et al., 1995b; Amunts et al., 1996, 1997; Geyer et al., 1996, 1997). Thus, this procedure avoids observer-dependent influences in defining areal borders and makes possible the statistical testing for significant changes in cytoarchitectonic organization. An analysis of 10 human brains Amunts, K., Schleicher, A., Buerger, U., Mohlberg, H., Uylings, H. B. M., & Zilles, K. (1999). Broca's region revisited: Cytoarchitecture and intersubject variability. The Journal of Comparative Neurology, 412, 319-341.
LOT Summer 2006Loss of speech85 0% depth = boundary between layers I and II; 100% = boundary with the white matter Mean cell density profiles Ordinates: Gray Level Index (GLI) in % Averages of 10 individual profiles (Amunts et al. 1999)
LOT Summer 2006Loss of speech86 Vertical lines of penetration Location of the image in A
LOT Summer 2006Loss of speech87 The results, in synthesis: Area 44 was identified on the basis of conspicuously large pyramidal cells in deep layer III and in layer V and by a barely recognizable dysgranular layer IV, which was invaded to different degrees by layer III and V pyramidal cells. Area 45 differed essentially from area 44 by the presence of a clearly visible layer IV. Due to the more pronounced layer IV, the horizontal layering of area 45 also appeared more conspicuous than did that of area 44. Layer IV of area 45, however, was less distinct than that in the rostrally adjoining prefrontal cortex, e.g., in areas 10 or 46 The cytoarchitectonic borders did not coincide with reliably identifiable macroscopic features, e.g., with a fundus of a sulcus. Thus, macroscopic anatomy and areal borders differ independently. Large intersubject variability in the cytoarchitecture of each cortical area
LOT Summer 2006Loss of speech88 The results, in synthesis: All five male brains showed a left-larger-than-right asymmetry in area 44. By contrast, the Asymmetry Coefficients for females in area 44 and for both sexes in area 45 were more evenly distributed, i.e., no interhemispheric asymmetry could be detected in these cases. Intersubject variability in cytoarchitecture was accompanied by intersubject variability in the positions of areas 44 and 45 relative to sulci and gyri. The spatial variability of borders relative to macroscopic features therefore is a relevant factor for the architectonic interpretation of functional imaging studies with a spatial resolution of a few millimeters. The classic maps do not provide information concerning the position of borders in the depths of a sulcus. Kononova (1938) found areal borders of areas 44 and 45 that did not coincide with the fundus of a sulcus. In some sections, area 45 does not reach the inferior frontal sulcus; in other sections, area 45 occupies parts of the dorsal wall of the middle frontal gyrus
LOT Summer 2006Loss of speech89 Inter-hemispheric asymmetries Although the volumes of area 44 differed across subjects by up to a factor of 10, area 44 but not area 45 was left-over-right asymmetrical in all brains. The interhemispheric differences in the volume of area 44 appear to be greater than those in cytoarchitecture. A left-over-right asymmetry was detected in all 10 cases. This finding supports that of a previous study in which a significantly larger area 44 was found on the left than on the right (Galaburda, 1980). Nine of the 10 subjects of that study had a larger area 44 on the left side. If the present sample is combined with that in the study by Galaburda, the incidence of leftward asymmetry (19 of 20 cases, 95%) matches the frequency of left-sided speech dominance in the general population and may structurally reflect the functional lateralization No consistent left–right difference in the volume of area 45 was found. Area 45 is not more symmetric than area 44; it is more heterogeneous pertaining to the direction of asymmetry. The data on volumes of areas 44 and 45 also clearly showed that the variability of this parameter and of the total brain weights (and, thus, brain volumes) are considerable.
LOT Summer 2006Loss of speech90 Individual Statistically defined maps versus visible anatomy
LOT Summer 2006Loss of speech91 Brodmann 1909 Economo & Koskinas 1925 Sarkisov et al. 1949 Variation in the anatomical definition of Areas 44 and 45 (Broca’s area) (Amunts et al. 1999)
LOT Summer 2006Loss of speech92 Broca’s aphasia revisited (Friedmann 2006) n Who did the cat chase? AC n Which dog did the cat chase? C n WHO is a pure operator, while WHICH is discourse-dependent and therefore computationally “more costly” (Hickok and Avrutin 1995; Tait 1995; Avrutin 2006) n Strong asymmetry between tense and subject- verb agreement inflection (tested in many languages) n Subject-verb agr. 65% correct or more n Tense is at chance level
LOT Summer 2006Loss of speech93 Broca’s aphasia revisited (Friedmann 2006) n A = affected NA = not affected n A Subject pronouns NA Object pronouns n A Relatives NA Reduced relatives n A Wh-questions NA yes/no questions n A Subordination conjunctions n NA Coordination conjunctions n Language variability: n A yes/no questions in Dutch, English and German n NA yes/no questions in Hebrew and Arabic
LOT Summer 2006Loss of speech94 The Tree Pruning Hypothesis (TPH) (Friedmann, 1998, 1999, 2006; Friedmann and Grodzinsky, 1997, 2000) n In essence: The highest functional nodes in the syntactic tree are selectively affected CP C’ C TP T’ TNegP AgrP Agr’ vPvP Wh-question Complementizer Tense Agreement milder severe
LOT Summer 2006Loss of speech95 The Tree Pruning Hypothesis (TPH) (Friedmann, 1998, 1999, 2006; Frriedmann and Grodzinsky, 1997, 2000) n Recovery of S.B. a 20 years-old Hebrew speaker with traumatic brain injury (Friedmann, 2005, 2006) CP C’ C TP T’ TNegP AgrP Agr’ vPvP Wh-question Complementizer Tense Agreement 15 months 6.5 months 4.5 months