Garcia_2006 - Fundamentos Neurobiologicos Cognitivos Evolutivos Lenguaje Natural

7/27/2019 Garcia_2006 - Fundamentos Neurobiologicos Cognitivos Evolutivos Lenguaje Natural

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Fundamentos neurobiolgicos, cognitivos y

Evolutivos del lenguaje natural

Dr. Ricardo Garca V. 2006.


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EVOLUTIONARY ASPECTS

Human-specific skill, althoughsome primates have been able tolearn some sign language viaextensive instruction(language?).

- Evolved 0.22 million years ago Speech capabilities (development

of vocal tract)

Brain adaptation for language:

- Structural asymmetries inthe brain, e.g., the planumtemporale

- Functional asymmetries inthe brain, e.g., language left-lateralized.


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Geschwind & Levitsky,1968


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AChE-RICH MAGNOPYRAMIDAL

NEURONS SIZE IN BROCAS AREA


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AChERN LEFT-RIGHT

ASYMETRY


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Pro A Tpt

Galaburda & Sanides, 1980


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LATERALIZATION OF

LANGUAGE

LEFT hemisphere

Analytic processing

Better ability to process

temporal aspects oflanguage

Sequences of units These aspects are very

important in languageprocessing, e.g.,

understanding of speech.Some disorders oflanguage may be due toproblems with timingability

Yet, some aspects oflanguage are typical forthe RIGHT hemisphere

Holistic processing Prosody: melody, tone ofvoice, stress

Emotional aspects ofspeech

Understanding ofhumour, metaphor, moral

Capable of understandingsimple speech


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THE MODERN VIEW OF

LANGUAGE IN THE BRAIN Brocas area and Wernickes area not homogenous pieces of tissue:

can be subdivided into functionally distinct parts.

Damage in Brocas or Wernickes area does not correspond strictly to

the aphasia syndromes the classical model predicts. Brocas area activated also in inputprocessing of language (not only

production), The left inferior frontal cortex (incl. Brocas area) mayplay a language executive role in coordinating phonological, syntacticand semantic processes in posterior areas.

Wernickes area is important in auditory processing but is not the only

location where language comprehension occurs (this involves severalregions).

There are important language-related areas outside the classical ones:e.g., middle and inferior sections of the temporal lobe, inferior parietalcortex, basal ganglia and cerebellum.


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Neural correlates of

- orthographic processing

- phonological processing

- morphological processing

- syntactic processing

- semantic processing


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Orthographic Processing:

FUNCTIONAL NEUROIMAGING STUDIES

- Left ventral occipito-temporal areas, complex visual processing- Visual Word Form Area: left fusiform gyrus? (E.g. Cohen & Dehaene, 2004,

Neuroimage)

An early PET study

McCandliss,Cohen & Dehaene,

2003, Trends in Cognitive Sciences


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Neural correlates of phonological processing

LESION STUDIES:

Conduction aphasia

-repetition disproportionately

severely impaired

- Main problems in the proper

choice and sequencing of

phonemes in speech output,

leading to numerous

phonological errors


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From Hickok & Poeppel (2000) Towards a functional

neuroanatomy of speech perception. Trends in Cognitive

Sciences, 4, 131-138. http://www.ling.umd.edu/Poeppel/


phonological processing


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Neural correlates of morphological processing

- Patients with predominantly temporallobe

lesions have more trouble producing

irregular (e.g., drive-drove) than regular

(talk-talked) verb forms.

- Patients with predominantlyfrontal/basal

ganglia lesions have more trouble producingregular than irregular verb forms.

Regular

Irregular

LESION STUDIES

- Inflectional and derivational morphology, and compounding can be

selectively impaired in aphasia

Ullman et al. (1997) A neural dissociation within language: evidence that the mental dictionary is part of

declarative memory, and that grammatical rules are processed by the procedural system. Journal of

Cognitive Neuroscience, 9, 266-276.


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morphological processing

FUNCTIONAL NEUROIMAGING

STUDIES

Brain areas related to

1) memorizingand2) recognizing

inflected (e.g., auto+ssa) vs. uninflected

(e.g., aurinko) Finnish nouns:

Increased activation especially in Brocas

area and superior temporal area.

M. Laine, J. Rinne, B.J. Krause, M. Ters & H.

Sipil (1999),Neuroscience Letters, 271, 85-88.,

Lehtonen, Vorobyev, Hugdahl, Tuokkola & Laine,

in preparation

1)

2)


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Neural correlates of syntactic processing

LESION STUDIES

- at word level, patients with left frontal damagecan have more trouble with verbs than with

nouns, while patients with left temporal damage

can have more trouble with nouns than with verbs

- at sentence level, agrammatism /morphosyntactic difficulties inproduction has

been associated to damage in left frontal areas

(e.g., Brocas)

- at sentence level, morphosyntactic difficulties incomprehension have been associated with a

variety of left perisylvian lesions

verbsnouns


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syntactic processing


Processing syntactically complex vs. simple

sentences

A review by Kaan & Swaab, TICS, 6(8), 2002

- Brocas area activation for

many tasks involving syntactic

processing: e.g., processing of

complex vs. simple sentences

(see figure), and syntactic

violations

- However, many other areas

are relevant as well!

- No unique area for syntax,different parts of the network

are recruited for different

aspects of processing(The same seems to be true for

most other subcomponents oflanguage)


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Neural correlates of semantic processing

LESION STUDIES

- Wernicke patients can have problems with semantic tasks

- Some dementia patients exhibit a slowly progressive condition coined as

semantic dementia. It is associated with left temporal lobe damage.

- There can be category-specific naming disorders -> distinct areas for

different categories of concepts, e.g., for tools and animals.


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semantic processing

FUNCTIONAL NEUROIMAGING

STUDIESBrain regions activated during

various lexical-semantic processing

tasks include, but are not limited to

the following:- left inferior frontal lobe

- left inferior parietal

posterior superior temporal

- left fusiform/inferior temporo-

occipital regions


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NON HUMAN PRIMATE BRAIN

ABOITIZ, GARCIA, BRUNNETI, BOSMAN, 2006


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Rauschecker y Tian 2000

Garcia_2006 - Fundamentos Neurobiologicos Cognitivos Evolutivos Lenguaje Natural

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