Neurolinguistics

Question 1

What is neurolinguistics?

Answer 1

Explores how the brain implements processes to produce and comprehend language (as an interdependent task part of multiple brain networks) –> physiological processes by which the brain processes language and speech

Question 2

Localization

Answer 2

Localization of cerebral structures responsible for linguistic processes

Question 3

Localization: Aphasiology era (19th c.)

Answer 3

Classical model articulated in centers and pathways in the left hemisphere, data comes from autopsies

Question 4

Localization: Neuroimaging era (1990s-present)

Answer 4

Disentangling brain regions involved in linguistic structure –> widely distributed representation of language in the brain

Question 5

Anatomical correlates of speech/language

Answer 5

• Frontal and temporal lobe of left hemisphere are most involved
• Inferior frontal gyrus (Broca’s area, 1865): speech control and production
• Middle temporal gyri (Wernicke’s area, 1874): language comprehension
• Subcortical areas: basal ganglia, hippocampus, amygdala

Question 6

Broca-Wernicke-Geschwind model of language (1972)

Answer 6

• One area dedicated to production, one are dedicated to comprehension –> interact to form working language
• Connective pathway: language generation flows from posterior to anterior in the left hemisphere
• TOO SIMPLE –> language is not strictly in left hemisphere (lesion methodology not effective to examine the brain)
• 1990s technology allows exploration of the ongoing performance of speech, temporal dynamics

Question 7

Brain imaging technology

Answer 7

• PET and fMRI use BOLD signals to measure changes in blood flow related to cognitive conditions –> reveals structures involved in language, high spatial resolution
• EEG and MEG use ERP to measure post-synaptic electrical activity –> direct measure of cognitive activity, time-sensitive
• ERP components: N400 (400ms to recognize incorrect semantic sentence), ELAN/P600 (recognizing syntactic violations) –> show that the brain responds differently to syntactic and semantic errors

Question 8

Dual-stream model

Answer 8

• Revision of structural organization by looking at functional neuroanatomy of language via ventral (bilateral organization in comprehension) and dorsal (left hemisphere dominant in production –> unique in humans) streams
• Emphasizes distributed network of language

Question 9

Brain areas involved in linguistic processes

Answer 9

1. Phonological processing: superior temporal lobe, both hemispheres
2. Morphological processing: left-lateralized frontotemporal system (irregular forms of words processed bilaterally)
3. Syntactic processing: left inferior frontal gyrus (Broca’s)
4. Semantic processing: distributed
   –> consistent across dialects, presentation, developmental experiences, stable over time