Interpreting Neurolinguistic Evidence

Careless thinking and critical thinking

Ling 411 – 21

Schedule of Presentations

DelclosPlanum Temp

BanneyerCategories

Ruby TsoWriting

BosleySynesthesia

McClureGram.-Broca

EzzellLg Dev. (Kuhl)

Rasmussen2nd language

BrownLg&Thought

Gilcrease-Garcia

AG

KobyMusic

TsaiTones

RobertsMTG

MauvaisLH-RH anat.

SheltonThalamus

DelgadoAmusia

Joyce LiuRH functions

Tu Apr 13 Th Apr 15 Tu Apr 20 Th Apr 22

Interpreting Linguistic EvidenceCareless 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

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)

Perceptual structures in motor production

Perceptual structure is used in two ways1. 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.

Interpreting Linguistic EvidenceCareless 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

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)

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.

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.

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 & RobertsSpeech and Brain Mechanisms(1959: 163)

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

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

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

Insula and operculaView 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

Original Brodmann Map - Colorized

Outlines - with Functional Attribution

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

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)

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)

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)

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

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)

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

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

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)

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

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 opercularis3.Phonemic disintegration – primary motor

cortex4.Defects of lexical access – pars triangularis

and adjacent frontal cortex5.Mixed defects

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?

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

Interpreting Linguistic EvidenceCareless 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

Friederici Fig. 1Syntactic 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.

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.

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)

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.

Trends in Cognitive Sciences vol. 13, Issue 8,

September 2009. pp. 369-370.

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

Interpreting Linguistic EvidenceCareless 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

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 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

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 processingand the lexicon (1995)

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?

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)

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

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

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

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

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)

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 …”

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?

Corpus Callosum

(revealed by excision of top of right

hemisphere)

Corpus Callosum

Interpreting Linguistic EvidenceCareless 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

Mirror Neurons

“What makes them so smart?” (already considered)

• It’s a matter of hierarchical organization

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

Interpreting Linguistic EvidenceCareless 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

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….

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

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?

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.

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

Vector coding vs. Local coding

Vector coding requires only a small bus•A 32-bit bus can carry and of 232 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?

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?

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

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

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!”

end