The Brain And Language Flashcards
Why study the brain to learn about language
The study of neural mechanisms can inform our understanding of the cognitive architecture of language
Lesion studies:
ModulRity of language sub processes
Necessity and sufficiency of brain regions for language
Brain maturation and language development:
The appearance of behaviours can tell us about adult cognition was
Describe Broca’s area
Cortical region in the posterior portion of the left inferior frontal gyrus thought to be involved in the production of speech
Describe wernickes area
Region of cortex in the superior and posterior region of the left temporal lobe that is involved in language comprehension
What is arcuate fasciculus
A white matter tract connecting Wernickes area and frontal premotor/motor area
Connections are bi-directional
What is brocas aphasia
Malted by a deficit in the production of function words.
Nouns and verbs are better preserved
Articulation is okay
Writing impaired
Suggests deficit in grammar production
What is wernickes aphasia
Impaired grammatical comprehension
Production of fluent but ungrammatical speech with paraphasias
Paraphasias - production of unintended syllables, words, or phases
What is conduction aphasia
Language disturbance characterised by
relatively fluent spontaneous speech
Good comprehension
Poor repetition associated with abundant phonological paraphasias
What is the classic model of language processing in the brain
Geschwind (1972)
Input to sensory areas, relayed to wernickes area the to brocas finally to motor cortex
Caramazza and zurif (1976) study
Caramazza and Zurif (1976)
Studies patients with damage to Broca’s area, wernickes area, or the arcuate fasciculus
Task required patients to choose a picture that corresponded to the scenario
- The book that the girl is reading is yellow
- The horse that the bear is kicking is brown
Semantic can disambiguate sentence 1 but help less so with sentence 2.
Thus more reliance on syntax is necessary for sentence 2
Broca’s conduction aphasics performed near perfectly on sentences where they could use semantics. Their performance dropped to chance when they had to relay on syntactic info
Evidence challenging Geschwind et al (1972) model of the brain
Dronkers and Wilkins (2004)
Brain regions outside the classically-defined areas are involved
Dronkers & Wilkins (2004)
Found that lesions to five left hemisphere brain regions affected comprehension but Broca’s area and wernickes area were not found to significantly alter language comprehension
Evidence challenging Geschwind et al (1972) model of the brain
Right hemisphere
Right hemisphere also contributes to language
Language lateralised and usually depends most on the left hemisphere
But
Relative performance differences are seen with side of presentation
Word - non-word decision:
Right visual field or right ear/left hemisphere faster and more accurate
Right-hemispheric activation usually apparent in brain imaging studies of language
Comprehending humour (Bihrle, et al 1986) and metaphor (Schmidt, DeBusse, and Sefer, 2007) involve distant semantic priming in the right hemisphere
Phonology
Anterior lesions associated with deficit in phonetic control, leading to inappropriate phonemic output
Posterior lesions leads to inappropriate phoneme
Syntax (rules governing how words are put together in sentences
Anterior aphasia - compromised ability both to produce and to comprehend the grammatical aspects of language
Semantics
Compromised in patients with posterior aphasia
Intact in anterior aphasics
Networks of brain regions model
Networks of brain regions may be the best way to characterise how the brain processes language
Vigneau et al (2006)
Meta analysis of 126 neuroimaging studied to identify phonological, semantic and sentence processing networks (brain regions separated by space but active in concert)
Results argue for large scale architecture networks rather than modular organisation of language in left hemisphere
Examples of network model
Anterior areas eg Broca’s involved in syntactic processing and in effortful retrieval of phonological and semantic aspects of words
Posterior language areas are involved in semantic processing as well as phonological processing
Most aspects of language processing involve meteors that span the anterior and posterior areas
