More on the Functional Neuroanatomy

of Language

Ling 411 – 20

Schedule of Presentations

DelclosPlanum Temp

BanneyerCategories

Ruby TsoWriting

BosleySynesthesia

McClureGram.-Broca

EzzellLg Dev. (Kuhl)

Rasmussen2nd language

BrownLg&Thought

Gilcrease-Garcia

AG

KobyMusic

TsaiTones

MauvaisLH-RH anat.

SheltonThalamus

DelgadoAmusia

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

Hickok’s proposal on conduction aphasia

At least one type of conduction aphasia results from damage to phonological processing systems in auditory cortex which participate both in speech perception and in speech production• i.e., Wernicke’s area

The asymmetry between production (impaired) and comprehension (spared) can be explained in terms of different degrees of lateralization in the … systems that support (or can support) these functions

(2000: 89)

Why isn’t this Wernicke’s aphasia?

The area identified by Hickok for conduction aphasia is Wernicke’s area•Hickok claims that such damage is

responsible for conduction aphasia

Conduction aphasia and Wernicke’s aphasia• In conduction aphasia

Comprehension is relatively ok

•Hickok claims the RH pSTP also participates in speech recognition

Patient is aware of errors in repetition

•Hickok proposes that in Wernicke’s aphasia the damage extends beyond Wernicke’s area MTG (p. 101), (maybe also AG?)

Hickok & Poeppel (2000)

Left temporal-parietal-occipital junction area is “typically involved to some extent in Wernicke’s aphasia, which … has a prominent post-phonemic component to the deficit profile. (Toward a functional neuroanatomy of speech perception, p. 7)

MR template – Wernicke Aphasia (patient I)

Poster-ior portion of super-ior and middle temp-oral gyri

MR template – Wernicke Aphasia (patient II)

Super-ior temp-oral gyrus, AG, SMG

Hickok’s proposal on speech perception

The primary substrate for speech perception is the posterior temporal plane (pSTP) • pSTP – Heschl’s gyrus plus planum temporale

Conduction aphasia can result from damage to exactly this area in left hemisphere

Apparent paradox:•Comprehension is preserved in conduction aphasia

Explanation:•Speech perception is subserved by pSTP in both

hemispheres

(2000: 90)

RH involvement in speech perceptionIsolated RH

Evidence from tests of isolated RH•Split-brain studies

•Wada test Sodium amytol, sodium barbitol

•Discrimination of speech sounds

•Comprehension of syntactically simple speech

(Hickok 2000: 92)

Benson and Ardila on conduction aphasia

“… a single type of aphasia may have distinctly different loci of pathology. Both conduction aphasia and transcortical motor aphasia are examples of this inconsistency.” (117)

(See also p. 135)

Hannah Damasio on conduction aphasia

“Conduction aphasia is associated with left perisylvian lesions involving the primary auditory cortex…, a portion of the surrounding association cortex…, and to a variable degree the insula and its subcortical white matter as well as the supramarginal gyrus (area 40). Not all of these regions need to be damaged in order to produce this type of aphasia. In some cases without involvement of auditory and insular regions, the compromise of area 40 is extensive…. In others, the supramarginal gyrus may be completely spared and the damage limited to insula and auditory cortices … or even to the insula alone….”

(1998: 47)

CT template – Conduction Aphasia (patient I)

CT template – Conduction Aphasia (patient II)

Left auditory cortex and insula

Kurt Goldstein on Conduction Aphasia

Kurt Goldstein (1878-1965) • German

• Studied with Wernicke

• Influenced by Gestalt psychology (Koffka 1935)

Adopted a “holistic” approach• Became the best-known spokesman for this

approach

• Important publication in 1948

Criticized the Wernicke-Lichtheim view of conduction aphasia• Not the arcuate fasciculus but a central area

• Proposed the term ‘Central Aphasia’

Now we see that there are really three kinds of conduction aphasia

3 or 4 types of conduction aphasia

Damage to arcuate fasciculus•The classical one

Proposed by Wernicke and Lichtheim Doubted by Hickok

•But Hickok is wrong!

Damage to SMG•Proposed by Goldstein

•Supported by Hickok

Damage to Wernicke’s area (but not to AG)•New proposal of Hickok

Possible 4th type: Damage to insula

Repetition in Wernicke’s aphasia

Model for Repetition black

shoe

He parks the car

It goes between two others

Patient’s Response blackboard

shoelace

He park … he came with the car. He came with his car.

It went two cars … between the cars

Goodglass on conduction aphasia

Unlike the patient with Wernicke’s aphasia, patients with conduction aphasia are usually acutely aware of the inaccuracy of their production and make repeated attempts at self-correction. As they do so, they may correct one portion of the target while introducing a new error elsewhere, sometimes wandering further afield and sometimes approaching closer to or even succeeding in saying the desired word.

(1993: 142)

Picture naming in conduction aphasia

Picture of..

whistle

pretzel

Patient’s Response

tris.. chi.. trissle.. sissle.. twiss.. ciss.

trep.. tretzle.. trethle.. tredfl… ki

Lamb’s email query to Hickok (April 1, 2010)

Hi Greg - In my neurolinguistics class we have just been considering your 2000 paper from the Grodzinsky et al. volume, with its new perspective on, among other things, these two types of aphasia. Very intriguing, but I have a question:

How do you explain this:When you give a conduction aphasic words to repeat, he/she commonly produces a phonemic paraphasia and then keeps trying, since he/she recognizes the error; but a Wernicke's aphasic usually stops after one incorrect repetition, evidently unaware of the error.

Acc. to your proposal, both types of aphasic have LHphonological recognition wiped out, and both have intact RH pSTG.

Hickok’s response (April 1, 2010)

Hi Syd, Good to hear from you. That is an interesting question. I think there are two possibilities. One is that the conduction aphasics don't have as much damage to the left hemisphere phonological systems we (I) might have thought. I.e., the damage is more often involving theposterior Sylvian region (Spt). The intact left and right hemi phonological systems allow the patient to clearly recognize their errors and self correct. Wernicke's on the other hand typically have extensive damage to the left hemi phonological systems which, because of their rolein production, may have a larger role in self monitoring. Another possibility, perhaps in conjunction with the first, is that wernicke's have damage to semantic (access) systems as well. it may be much harder to notice a phonological error if you can't tell whether it is a word or not.

The Connection between Phonological Recognition and

Phonological Production

Hickok (2000) proposes a revision of the standard hypothesis

The revision is like that previously proposed by Goldstein

Now, evidence from DTI (cf. Friederici)

The Perception-Production Interface

We have phonological recognition in Wernicke’s area• And in RH homolog of Wernicke’s area

And phonological production in Broca’s area• And in RH homolog of Broca’s area

Clearly, they have to be connected The traditional view

• Direct connection: the arcuate fasciculus • Proposed by Wernicke, supported by Geschwind

Alternative view• Supramarginal gyrus (SMG) as intermediary• Proposed by Hickok

with support from Damasio and Goldstein

REVIEW

The Intermediate System Hypothesis

SpeechProduction

SpeechRecognition

Supramarginal Gyrus

Auditory-Motor Interface

Arguments for Direct Connection Hypothesis

No additional intervening structure needed

We have anatomical evidence for the arcuate fasciculus•And for its connections from Wernicke’s

area to Broca’s area

Arguments for SMG Interface Hypothesis

Damasio cites SMG damage as a major cause of conduction aphasia• Consistent with earlier findings of Goldstein

“Central aphasia” (Goldstein 1948)

Connectivity studies in non-human primates fail to find direct connection between auditory cortex and ventral posterior frontal lobe• But support the claim that the lower parietal lobe

provides an interface between these areas (Hickok 2000: 99)

SMG is a likely site of higher-level proprioceptive processing of speech

Arguments for SMG Interface Hypothesis

Damasio cites SMG damage as a major cause of conduction aphasia• Consistent with earlier findings of Goldstein

“Central aphasia” (Goldstein 1948) Anatomical studies in macaque monkeys fail to

find direct connection (between corresponding areas) (Hickok 2000: 99)

SMG is a likely site of higher-level proprioceptive processing of speech• (next slide)

Motor and Somatosensory Areas for speech

Mouth

HandFingers

Arm

Trunk

Leg

Central Sulcus

1 2 3

4

1 – Phonological production

2 – Articulation

3 – Articulatory monitoring

4 – Phonological monitoring

Post-Central Sulcus

Presumed interconnections of speech areasCentral Sulcus

1 2 34

1 – Phonological production

2 – Articulation

3 – Articulatory monitoring

4 – Phonological monitoring

5 – Primary auditory

6 – Phonological recognition

Post-Central Sulcus

65

And there’s more than meets the eye

The phonological recognition area includes the temporal plane

The phonological monitoring area includes the parietal operculum

Both large areas

The Sylvian FissureREVIEW

Evidence for left pSTP involvement in speech production

Erratic speech of Wernicke’s aphasics Conduction aphasia from damage to left pSTP Intraoperative stimulation of left pSTP

• “distortion and repetition of words and syllables” (Penfield & Roberts 1959)

• N.B.: As in Wernicke’s aphasia MSI study shows activity in left pSTG just before

speech production (picture naming) (Levelt et al. 1998)

fMRI study: similar results – no RH activity shown (Hickok et al. 1999)

(Hickok 2000: 93-4)

REVIEW

An MSI study from Max Planck Institute

Levelt, Praamstra, Meyer, Helenius & Salmelin, J.Cog.Neuroscience 1998

Diffusion Tensor Imaging (DTI)

New and very informative technique Uses MRI Allows observation of molecular diffusion in

living tissues Makes use of

•Brownian movement

•Magnetic properties of hydrogen nuclei Two of them in every water molecule (H2O)

Water moves along lines of least resistance• i.e., along white matter axons

aided by myelin

Uniformity of cortical strucureacross mammals?

The hypothesis of uniformity•Very important for perceptual neuroscience

•Allows data from experiments on cats and monkeys to be applied to human cortical structure and function Including higher levels – language

But: this hypothesis applies to grey matter•Not white matter

Cortico-cortical connections

DTI shows that white matter connections differ across mammals

Arcuate fasciculus in different primates

Asif Ghazanfar, Nature Neuroscience 11:4.382-384, April 2008

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:Brodmann areas in LH

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.

What?!!!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)

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

end