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Interpreting Neurolinguistic Evidence Careless thinking and critical thinking Ling 411 – 21.

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Presentation on theme: "Interpreting Neurolinguistic Evidence Careless thinking and critical thinking Ling 411 – 21."— Presentation transcript:

1 Interpreting Neurolinguistic Evidence Careless thinking and critical thinking Ling 411 – 21

2 Schedule of Presentations Delclos Planum Temp Banneyer Categories Ruby Tso Writing Bosley Synesthesia McClure Gram.-Broca Ezzell Lg Dev. (Kuhl) Rasmussen 2 nd language Brown Lg&Thought Gilcrease-Garcia AG Koby Music Tsai Tones Roberts MTG Mauvais LH-RH anat. Shelton Thalamus Delgado Amusia Joyce Liu RH functions Tu Apr 13 Th Apr 15 Tu Apr 20 Th Apr 22

3 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Retrieval of words, meanings Communication between subsystems

4 Wernicke’s area and speech production Examples of careless thinking: Steven Pinker: Wernicke’s area …was once thought to underlie language comprehension. But that would not explain why the speech of these patients sounds so psychotic. The Language Instinct (1994) Friedemann Pulvermüller: …patients with Wernicke’s aphasia have difficulty speaking…. These deficits are typical…and cannot be easily explained by assuming a selective lesion to a center devoted to language comprehension. The Neuroscience of Language (2002)

5 Perceptual structures in motor production  Perceptual structure is used in two ways 1. Planning (e.g. visualizing while painting) 2. Monitoring  Examples Phonological recognition in speech production  Cf. Wernicke’s aphasia Painting Musical production Baseball, soccer, tennis, etc.

6 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Retrieval of words, meanings Communication between subsystems

7 Broca’s area and speech production - I Careless thinking previously considered: John Pinel (Biopsychology textbook): Surgical excision of Broca’s area failed to result in loss of speech production (after recovery from surgery)

8 Broca’s Area: Not for Speech Production? Surgical excision was done in two stages. Following completion of the second stage, no speech- related problems were reported. John Pinel, Biopsychology (1990:560), Adapted from Penfield & Roberts, 1959 Patient D.H.

9 Broca’s Area: Not for Speech Production? What Pinel neglects to mention, but it is in Penfield & Roberts: Patient D.H. was a young boy who had been having seizures, originating in this part of his brain. John Pinel, Biopsychology (1990:560), Adapted from Penfield & Roberts, 1959 Patient D.H.

10 More on patient D.H.  Eighteen years old at time of surgery  Had suffered from seizures causing an inability to speak from the age of 3 1/2  Apparently, “the congenital abnormality had caused displacement of function” Penfield & Roberts Speech and Brain Mechanisms (1959: 163)

11 Broca’s area and speech production - II  Influential paper by Alexander et al. (1990)  Motivation for the study Maybe it’s not just Broca’s area damage that is responsible for some of the symptoms of “Broca’s aphasia” Maybe some of them result instead from damage to neighboring areas  They studied a group of patients  Distinguished 3 subtypes of Broca’s aphasia

12 Three subtypes in Alexander study 1.Impaired speech initiation Symptom traditionally attributed to transcortical motor aphasia Area of damage: frontal operculum 2.Disturbed articulatory function Area of damage: lower primary motor cortex 3.The classical Broca’s aphasia syndrome More extensive damage

13 Type I  One patient  Area of damage Frontal operculum Adjacent middle frontal gyrus Subjacent subcortical white matter  Speech quality normal  Normal repetition  Speech terse and delayed in initiation  Speech grammatically correct!  Anomia and semantic paraphasias

14 Insula and opercula View with opercula pulled back to expose insula 1.Short gyri of insula 2.Long gyrus of insula 3.Superior temporal gyrus 4.Circular sulcus of insula 5.Frontal operculum 6.Frontoparietal operculum 7.Temporal operculum

15 Original Brodmann Map - Colorized Outlines - with Functional Attribution

16 Type I – critical appraisal  Area of damage Frontal operculum Adjacent middle frontal gyrus Subjacent subcortical white matter  Symptoms Speech quality normal Normal repetition Speech terse and delayed in initiation Speech grammatically correct! Anomia and semantic paraphasias  The symptoms are those of transcortical motor aphasia

17 Type I (cont’d) (from Alexander study)  Other relevant studies Patients with frontal operculum lesion but with primary motor cortex spared Symptoms like those usually called TCMA Speech output  “Terse, laconic”  Grammatical, sentence-length  Semantic paraphasias  Normal articulation Evidently, damage to subjacent white matter “is essential for lasting aphasia after lesions in the frontal operculum” (Alexander et al. 1990” 357)

18 Type I (cont’d) (from Alexander study)  Other relevant studies Patients with frontal operculum lesion but with primary motor cortex spared Symptoms like those usually called TCMA Speech output  “Terse, laconic”  Grammatical, sentence-length  Semantic paraphasias  Normal articulation Evidently, damage to subjacent white matter “is essential for lasting aphasia after lesions in the frontal operculum” (Alexander et al. 1990” 357)

19 Type I (cont’d) (from Alexander study)  Other relevant studies Patients with frontal operculum lesion but with primary motor cortex spared Symptoms like those usually called TCMA Speech output  “Terse, laconic”  Grammatical, sentence-length  Semantic paraphasias  Normal articulation Evidently, damage to subjacent white matter “is essential for lasting aphasia after lesions in the frontal operculum” (Alexander et al. 1990” 357)

20 Type II  Patients 2-6 in Alexander et al. (1990) study  Areas of damage Frontal operculum Lower primary motor cortex Anterior insula White matter deep to these regions  Right facial paresis and mild right hand weakness  Defective articulation  Sentence-length grammatically normal utterances! Except for initiation struggle Except for patient #6: single word utterances

21 Type II (cont’d)  Other studies support the attribution of dysarthria to primary motor cortex Patients with  Small shallow lesions in lower motor cortex  Frontal operculum not involved Labels that have been used  Aphemia  Cortical dysarthria  Apraxia (Alexander et al. 1990: 357)

22 Type III  Patients 7-9 in Alexander et al. (1990) study  Areas of damage: Lower motor cortex and/or subjacent white matter Anterior superior insula Lateral putamen (a nearby subcortical structure) Frontal operculum spared  Right central facial paresis  Aphasia symptoms similar to Type II Including absence of agrammatism  Phonemic paraphasias in repetition  One patient (#9) had virtually no speech output

23 Receptive agrammatism  “All cases had some impairments in auditory comprehension at the level of complex sentences or multistep commands.” (Alexander et al. 1990: 360)  Indicates short-term memory deficit

24 Confounding factors  “We did not evaluate any of the patients in the acute phase of their illnesses; all were referred to the Boston VAMC for speech and language therapy.” (Alexander et al. 1990: 353)  Localization of lesions was done by CT scan – not sensitive enough to detect small areas of damage (360)

25 The importance of plasticity  “In the acute phase, these patients may have traditional, nonfluent aphasia – articulation impairment, prosodic impairment, and agrammatical, shortened utterances. The evolved disorder is, however, much less severe than that; grammatical, sentence-length utterances return, albeit still labored and paraphasic and with speech impairment.” (Alexander et al. 1990:361)  Recovery is not so good if extensive white matter involvement

26 Another study  Taubner, Raymer, and Hellman 1999, “Frontal-opercular Aphasia”: 5 types: 1.“Verbal akinesis” like Trans-cortical motor aphasia – supplementary motor area and cingulate gyrus 2.Disorders of grammar – pars opercularis 3.Phonemic disintegration – primary motor cortex 4.Defects of lexical access – pars triangularis and adjacent frontal cortex 5.Mixed defects

27 Proceed with Caution!  How should we interpret the results of the Alexander study?  Some researchers have concluded that damage to Broca’s area is not responsible for Broca’s aphasia after all Reason: No lasting impairment of speech production if only Broca’s area is damaged, without white matter involvement  Alternative explanation?

28 Alternative explanation  Plasticity  N.B. Patients were examined only after they had had time to recover, not in the acute phase  The evidence indicates that Functions of Broca’s area can be partly regained by recruitment of neighboring area(s) But: such recovery is impaired if there is also damage to subjacent white matter

29 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Retrieval of words, meanings Communication between subsystems

30 Friederici Fig. 1 Syntactic networks in the human brain. (a) Depicts the two neural networks for syntactic processing and their fronto- temporal involvement (function) schematically. (b) Shows fiber tracting as revealed by DTI (structure) in an individual subject: top right, with the starting point (green dot) being BA 44 and bottom right, with the starting point (blue dot) being the frontal operculum.

31 Friederici Figure 2 Fiber tracts between Broca's and Wernicke's area. Tractography reconstruction of the arcuate fasciculus using the two-region of interest approach. Broca's and Wernicke's territories are connected through direct and indirect pathways. The direct pathway (long segment shown in red) runs medially and corresponds to classical descriptions of the arcuate fasciculus. The indirect pathway runs laterally and is composed of an anterior segment (green), connecting Broca's territory and the inferior parietal cortex (Geschwind's territory), and a posterior segment (yellow), connecting Geschwind's and Wernicke's territories.

32 Wernicke’s & Broca’s areas for syntax? Combining functional MRI and DTI, two of these pathways were defined as being relevant for syntactic processes [44]. Functionally, two levels of syntactic processing were distinguished, one dealing with building a local phrase (i.e. a noun phrase consisting of a determiner and a noun ‘the boy’) and one dealing with building complex, hierarchically structured sequences (like embedded sentences ‘This is the girl who kissed the president’). DTI data [44] revealed that the frontal operculum supporting local phrase structure building [14] and [44] was connected via the UF to the anterior STG which has been shown to be involved in phrase structure building as well [14]. The dorsal pathway connects BA 44 which supports hierarchical structure processing [42] and [45], via the SLF to the posterior portion of the STG/STS, which is known to subserve the processing of syntactically complex sentences 51 I. Bornkessel et al., Who did what to whom? The neural basis of argument hierarchies during language comprehension, Neuroimage 26 (2005), pp. 221–233. Article | PDF (300 K) | View Record in Scopus | Cited By in Scopus (53)[51]. This latter network was, therefore, taken to have a crucial role in the processing of syntactically complex, hierarchically structured sentences. (Friederici 2009, p. 179)[44] [14][44][14][42][45]51ArticlePDF (300 K)View Record in ScopusCited By in Scopus (53)[51]

33 Critique of Friederici paper by Weiller et al. (August 2009) Friederici claims the dorsal pathway ‘to be crucial for the evolution of human language, which is characterized by the ability to process syntactically complex sentences’. … As suggested in our paper, ‘the involvement of the dorsal stream for processing of complex syntactic operations might be partially explained as a result of an increase in syntactic working memory load’ [2]. Syntax and memory are hard to keep apart.[2] Trends in Cognitive Sciences vol. 13, Issue 8, September pp

34 Hickok on phonological working memory “… Broca’s area and the SMG are involved in speech perception only indirectly through their role in phono- logical working memory which may be recruited during the performance of certain speech perception tasks.” Hickok 2000: 97 “The sound-based system interfaces not only with the conceptual knowledge system, but also with frontal motor systems via an auditory-motor interface system in the inferior parietal lobe. This circuit is the primary substrate for phonological working memory, but also probably plays a role in volitional speech production. Hickok 2000: 99

35 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Retrieval of words, meanings Communication between subsystems

36 Impairment of nominal concepts  Access to nominal concepts is impaired in extra-sylvian sensory aphasia  Type I – Damage to temporal-parietal- occipital junction area I.e., lower angular gyrus and upper area 37area 37 Poor comprehension Naming strongly impaired Semantic paraphasia  Type II –Damage to upper angular gyrus Variable ability to comprehend speech Naming strongly impaired Few semantic paraphasias Many circumlocutions

37 2 Cases of Rapp & Caramazza (1995)  E.S.T. (901b) – Left temporal damage “Meaning spared, couldn’t say the word”: R&C  J.G. (902a) – Left posterior temporal-parietal Meaning spared, couldn’t spell the word correctly, but phonological recognition okay Cf. Rapp & Caramazza, Disorders of lexical processing and the lexicon (1995)

38 Patient E.S.T. (Rapp&Caramazza 1995: 901b )  Left temporal damage  Shown picture of a snowman Unable to name it “It’s cold, it’s a ma… cold … frozen.”  Shown picture of a stool “stop, step … seat, small seat, round seat, sit on the…”  Shown written form ‘steak’ “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …”  What can we conclude?

39 Assessment of E.S.T. by Rapp & Caramazza  Responses of E.S.T. indicate awareness of the meanings ( SNOWMAN, STOOL, STEAK )  Therefore, “meaning is spared” (according to Rapp & Caramazza)

40 Warning: Proceed with caution  The assumption of Rapp&Caramazza is easy to make I.e., that meaning (conceptual information) is spared  But there’s more to this than meets the eye!  As we have seen, conceptual information is widely distributed  We only have evidence that some of the conceptual information is spared

41 Patient E.S.T. – a closer look  Left temporal damage  Picture of a snowman “It’s cold, it’s a ma… cold … frozen.”  Picture of a stool “stop, step … seat, small seat, round seat, sit on the…”  Written form ‘steak’ “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …”  These are not definitions  This is connotative information Vague semantic notions about the meanings

42 Compare patient J.G. (902a)  Damage: Left posterior temporal-parietal  Meaning spared, couldn’t spell the word correctly, but phonological recognition okay digit:  D-I-D-G-E-T  “A number” thief:  T-H-E-F-E  “A person who takes things”  These are actual definitions

43 The Role of RH in semantics  Conceptual information, even for a single item, is widely distributed A network Occupies both hemispheres  RH information is more connotative LH information more exact

44 Connotative information in RH  Tests on patients with isolated RH resulting from callosotomy  RH has information about (many) nouns and verbs Not as many as in LH  Semantic information differently organized in RH  Zaidel (1990): “… the right hemisphere is characteristically connotative rather than denotative …. The arcs [of the semantic network] connect more distant concepts … and the organizing semantic relationships are more loosely associative and dependent on experience” (125) Baynes & Eliason, The visual lexicon: its access and organization is commissurotomy patients (1998)

45 Semantic information: E.S.T. and J.G.  Patient J.G. – real definitions digit: “A number” thief: “A person who takes things”  Patient E.S.T. – connotative information snowman: “It’s cold, it’s a ma… cold … frozen.” stool: “ … seat, small seat, round seat, sit on the…” steak: “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …”

46 Conclusion about E.S.T.  RH semantic information is intact  LH semantic information is wiped out  Phonological information is spared in both hemispheres  Question: Why can’t the RH semantic information be conveyed to LH phonology?

47 Corpus Callosum (revealed by excision of top of right hemisphere) Corpus Callosum

48 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Retrieval of words, meanings Communication between subsystems

49 Mirror Neurons  “What makes them so smart?”  (already considered) It’s a matter of hierarchical organization

50 Implications of hierarchical organization  Nodes at a high level in a hierarchy may give the appearance of being very “smart”  This appearance is a consequence of their position — at top of hierarchy  As the top node in a hierarchy, a node has the processing power of the whole hierarchy Grandmother nodes Mirror neurons Compare:  The general of an army  The head of a business organization

51 Interpreting Linguistic Evidence Careless thinking and critical thinking  Wernicke’s area and speech production  Broca’s area and speech production  Broca’s area and Wernicke’s area in syntax  The meanings of words  “Mirror neurons” – very smart?  Invoking the computer metaphor Representation of information Retrieval of words, meanings Communication between subsystems

52 The brain and the computer Conference abstract, March 28, 2009: Mark Jude Tramo, MD PhD, Harvard, MIT, & Mass Gen Functional Brain Organization in Relation to Emotion and Meaning in Music When we experience the beauty of music…there is no sound in our brains…. All acoustic information striking our eardrums is transformed into neural information represented by patterns of electrical activity – strings if 0’s and 1’s whose bits vary depending on the pitch, loudness, duration, consonance, and timbre of each note, harmonic interval, and chord….

53 Retrieval from memory  “inability to retrieve the word” As if the word were stored in some kind of symbolic form in some memory location, from which it has to be retrieved  Better: inability to access the internal representation of the word

54 Links for intermodal communication  Examples: Phonological – grammatical – semantic Phonological recognition – phonological production  I.e., Wernicke’s area and Broca’s area  Two related problems: What information is transmitted? Over what kind of connection?

55 Transmitting information  For example, from angular gyrus to Wernicke’s area  Conceptual or lemma inf in AG  Phonological inf in Wernicke’s a. from Wernicke’s area to Broca’s area  Some kind of phonological information Some kind of code? Phonemic transcription? Phonological image in Wernicke’s a. Phonological motor program in Broca’s a.

56 What kind of connection?  Two possibilities The way its done in computers  Vector coding, a bus  Only a few fibers needed  But: some means of coding is needed Local coding, individual connections  A very large number of fibers needed  By comparison, grossly inefficient

57 Vector coding vs. Local coding  Vector coding requires only a small bus A 32-bit bus can carry and of 2 32 items of information The way it’s done in personal computers  Nowadays, many use a 64-bit bus  Local coding requires a very large bus A separate fiber for each item For arcuate fasciculus, hundreds of thousands  Anatomical evidence can provide answer How many fibers in arcuate fasciculus?

58 Anatomical evidence: Wernicke’s area and Broca’s area  Connected by arcuate fasciculus  Auditory phonological images linked to articulatory images  Individual connections would require many thousands of fibers  How many fibers in arcuate fasciculus?

59 How many Fibers in Arcuate fasciculus?  Selden (1985:300): “macroscopically most obvious”  Consists of axons of neurons distributed throughout Wernicke’s area  Therefore, millions of fibers  Different fibers originate in different locations throughout Wernicke’s area

60 How many fibers in arcuate fasciculus: theoretical calculation  From each minicolumn, at least one axon to Broca’s area  How many minicolumns in Wernicke’s area? 20 sq cm x 145,000 minicolumns per sq cm 2,900,000  Therefore, at least 2,900,000 axons in arcuate fasciculus

61 So what is the information that is sent?  We have to avoid thinking of the brain as a computer  An axon sends only one kind of information: Activation  Can come in different degrees i.e., different frequencies of firing Nothing else needed, since it is a unique connection  This is a property of connectivity All the information is in the connectivity “Connectivity rules!”

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