History and Schools of Neuroliguistics

Question 1

What is the definition of neurolinguistics?

Answer 1

[definition] the study of the neural mechanisms in the human brain that control the comprehension, production, and acquisition of language.

Question 2

What are some methods in neurolinguistics?

Answer 2

1. lesion studies
2. positron emission tomography
3. functional magnetic resonance imaging
4. electroencenphalography
5. magnetoencephalography

Question 3

What are lesion studies, and what is the important assumption when drawing conclusion from these studies?

Answer 3

Looks at localization and neural architecture (system breakdown).

– injury always takes away function (never adds)

Question 4

What is PET and what are it’s pros/cons?

Answer 4

[definition] a functional imagine technique which detects gamma radiation emitted by the tracer; a radioactive substance is injected into the blood stream and looked at with a PET scan.

[pros] good for temporal images
[cons] invasive, costly, risk of radiation to patients

Question 5

What is fMRI and what are it’s pros/cons?

Answer 5

[definition] a functional imaging technique which detects changes in blow flow using strong magnets
– uses BOLD signals (higher O2 levels are correlated with higher neuronal activity, which occurs when there is more work being done)

[pros] good spatial resolution, non-invasive
[cons] poor temporal resolution, costly

– problems for neurolinguistics is that you can’t really get headphones into a machine due to magnetic properties

Question 6

What is EEG and what are it’s pros/cons?

Answer 6

[definition] records electrical activity within the brain (as it is reflected along the scalp) using multiple electrodes; uses ERP as an electrophysiological response to a specific event (big ERP components: N400, P600, etc.)

[pros] good temporal accuracy, fairly affordable, non-invasive
[cons] poor spatial accuracy, and there is a possible downside in that you nearly always need to measure a disruption against ‘normal’

Question 7

What is MEG and what are it’s pros/cons?

Answer 7

[definition] records magnetic fields produced by electrical currents that occur naturally in the brain

[pros] good spatial and temporal accuracy, non-invasive
[cons] costly – like, super costly. requires grants, costly.

Question 8

What does P600 indicate?

Answer 8

it is an index of syntactic processing

Question 9

What does N400 indicate?

Answer 9

it is an index of semantic processing

Question 10

Who is William Wundt?

Answer 10

(1832 - 1920)

The founder of experimental psychology; viewed language as a mechanism to transform thought in sentence.

Question 11

Who is Franz Joseph Gall?

Answer 11

The founder of phrenology!
– measurements of the human skull (based on the concept that the brain is the organ of the mind, and that certain brain areas have localized and specific functions or modules)

Phrenology…

• • recognized uniformity and continuity of cortex
• • saw the cortex as the highest level of brain organization
• • looked at certain human abilities as being innate (this “surface map”); the development of the skull reflects the cortex underneath, and cranioscopy can give information about the cortex and therefore the relative representedness of the abilities

Question 12

What is localism?

Answer 12

The idea that different “higher functions” are localized in various different “centers” of the brain (mainly the cortex).
– these centers can be seen as “sisters”, ie. equally important, or there may be a particular center that is seen as hierarchically superordinate to others (ie. the prefrontal cortex)

[Gall, Broca]

Question 13

What is associationism?

Answer 13

The idea that higher functions are dependent on the associations (connections) between different ‘centers’ in the brain.
– aphasia results from broken connections between the centers that are needed for linguistic function

[Wernicke, Lichteim, Geschwind]

Question 14

What is dynamic localization?

Answer 14

The idea that different linguistic (sub-)functions are seens as localized (distributed) in different parts of the brain

• • in order to get more complex functions, these sub-functions must be combined (different areas combines)
• • the relationship between a localized lesion and the functions/phenomena that are distributed therefore becomes much more complex

[Luria, Vygotsky]

Question 15

What is the evolutionary view?

Answer 15

The idea that emphasizes that the structure of the human brain has developed in a layered manner from inner (lower) more primitive structures to the later developed superimposed cortical layers.
– emphasizes the role of all of these hierarchically developed layers in language and communication

1. from simple to more complex
2. from lower centers to higher centers
3. from more organized centers to more complex centers
4. from automatic to intentional

[J. H. Jackson]

Question 16

What is holism?

Answer 16

The idea the the brain (for higher functions at least) works as a whole

• • the cortex handles such things as “higher cognitive function”, “symbolic thinking”, “intelligence”, “abstraction”…
• • aphasia can be taken to be a sign of general cognitive loss (not a loss that affects language specifically)
• • cognitivism
• • equipotentiality

[Marie, Head, Goldstein]

Question 17

What is equipotentiality?

Answer 17

The notion that all parts of the cortex have the same functional potential (the size of brain lesions determines the extent of the aphasia)
– “unitarism”; the soul is one and cannot be devided

[Karl Lashley; behaviourism and the “apparent capacity of any intact part of a functional brain to carry out…the functions which are lost by the destruction of [other parts]”]

Question 18

Who is Paul Broca?

Answer 18

The man who founded Broca’s area (duh).

• • autopsied a patient (Tan) who could understand normal speech but could not speak or write a sentence ( = production deficit)
• • could only articulate the word “tan” (real name is Leborgne)
• • after autopsying eight similar patients with lesions in the LEFT FRONTAL LOBE Broca argued that we “speak with the left hemisphere”

Question 19

What are Broca’s theories of language in the brain?

Answer 19

1. language articulation lies in the third frontal convolution of the inferior frontal gyrus
2. there if left hemisphere dominance in language articulation
3. understanding language is a different cognitive task than producing it
4. language is lateralizde

Question 20

Who is Carl Wernicke?

Answer 20

Wernicke’s area!
– posterior part of the first/superior temporal gyrus and adjacent areas (parts of the angular gyrus, the supramarginal gyrus, and the second temporal gyrus are included)

Damage to this area disturbs language comprehension.

Wernicke imagined a specific “language gyrus” from Wernicke’s area (with receptive function) to Broca’s area (with expressive function).
– lesions in one of these areas OR in the connection between them would cause aphasia

Question 21

What are the important parts of Wernicke’s theory?

Answer 21

1. the identification of symptom complexes
2. the idea about flow of information
3. the idea of representation
   - - Broca’s area is said to have a “motor representation” of speech, while Wernicke’s area is said to have an “auditory sound representation” of speech

Question 22

What are the principles of modular language processing?

> > > ** «<

Answer 22

1. determinism: one and only one syntactic analysis at a time
2. simplicity: do not assume unnecessary structure
3. seriality: complete processing in one domain before processing in another domain begins (one structure at a time)
4. incrementality: process each new unit (word) when it becomes available
5. immediacy: process each new unit (word) when it becomes available (do not wait)
6. domain specificity: syntactic parser cares about structure building only

Question 23

What are the stages of modular language processing?

Answer 23

1. input
2. lexical processor
   - – categories

[stage 1]

3. syntactic parser
   - – syntactic structure

[stage 2]

4. thematic interpreter
   - – meaning

Question 24

What are mental modules?

Answer 24

[definition] specialized processing facilities that mediate between ‘peripheral’ sensory information and ‘higher’ levels of language processing.

• • support rapid online language processing
• • a set of automatized functions/operations needed to construct linguistic representations in real time on the basis of rapidly changing speech signals

Question 25

What are the properties of modular systems?

Answer 25

1. DOMAIN SPECIFICITY
   - - apply in only one restricted domain
2. MANDATORY OPERATION
   - - automatically triggered (no conscious choice to ‘understand’ speech)
3. LIMITED CENTRAL ACCESS
   - - no conscious awareness
4. FAST OPERATION
   - - high speed, automatic, reflex-like
5. INFORMATIONALLY ENCAPSULATED
   - - restricted to a certain type of information; no access from other domains
6. FIXED NEURAL ARCHITECTURE
   - - specialized neural anatomy
7. SPECIFIC PATTERNS OF BREAKDOWN
   - - specific, definable breakdown within module (cf. aphasia types)
8. MATURATIONAL SEQUENCING
   - - genetically specified (fixed) developmental trajectory (cf. critical period), environmental triggering but only that

Question 26

Why are modular models helpful?

Answer 26

They…

• • conceptualise the stages involved in language processing
• • examine components involved in different components of language processing and their interconnections (“boxes and arrows”; represent a linguistic function that cab be impaired independently)
• • provide a framework for assessment of aphasia and its treatment

Different models consider different aspects (ie. single words or sentence processing) but share many features (ie. distinct semantic and phonological levels)

Question 27

What do these modular MODELS assume?

Answer 27

1. functional modularity
   - - boxes = modules; can operate independently of other components
2. anatomical modularity
   - - boxes = modules = represent different parts of the brain; lesions can affect selected modules only; others left unimpaired
3. universality
   - - all people share the same general linguistic system (the structure and nature of which can be under dispute)
4. subtractivity
   - - damage to any area of the brain can only remove elements from the system

Question 28

What are Brodmann areas?

Answer 28

[Kordinian Brodmann; 1909]

Human cortical maps (+ other species).

Cytoarchitectural organization: classification based on the types of neurons he observed.

Question 29

What are the Brodmann areas for Wernicke and Broca’s area?

Answer 29

[Wernicke] 22

[Broca] 44, 45

Question 30

What is the language stream?

Answer 30

The arcuate fasciculus (‘curved bundle).

• • the traditional view is that the AF connects Broca’s and Wernicke’s
• • this is the language stream!

DTI is used to test this hypothesis and the connections are much more complex/diffuse than this!!

• • axons in the AF are substantially larger in humans than in other primates
• • but there are a lot of other tracts (ie. the superior longitudinal fasciculus [SLF], the inferior longitudinal fasciculus [ILF], the uncinate fasciculus [UF], and the inferior fronto-occipital fasciculus [IFOF])

Question 31

Who postulated a third language center/what is the third language center?

Answer 31

Ludwig Lichtehim!!

The third language center is an unspecified location in the brain that stores concepts and formulates/processes them in the “concept area”

• • not strictly a language area
• • distributed across the brain

Ludwig constructed a model of language function following and adding to Wernicke’s model (that weird triangle one).

• • mix of neuroanatomy and psychology (some areas defy localization)
• • the concept area allows for explanations of transcortical sensory and motor aphasia!! disrupted connections from either wernicke - concept or concept - motor.

Question 32

What are some problems with associations being the primary basis for inferences in early neuropsychology?

Answer 32

• • lacked rigorous quantitative measures (just identify a group of patients with fairly homogeneous functional impairment and fairly homogeneous physical impairment and call it a syndrome)
• • patients weren’t always described carefully

A big problem was also co-occurrence of symptoms!

• • models often assumed to directly map to underlying brain structures (so grouped into syndromes, ie. either Broca or Wernicke’s aphasics)
• • BUT there is the possibility of lesions in other areas, of a lack of lesions in the expected areas
• • the study of robust aphasic syndromes has not told us much about how language processing works or about the role specific brain regions for language related tasks

Question 33

What’s a solution to the problem of mapping brain regions to symptoms?

Answer 33

DISSOCIATION!!

• • for example, Broca’s aphasics can display specific deficits in the production of main verbs, but not in the production of object names (so if there is an issue in the production of object names it may not be B.A.)
• • this is a single dissociation, which does not rule out other interpretations (ie. the possibility of global deficit impairing general cognitive reserve and making verbs harder to read than nouns)
• • so the real solution is:

DOUBLE DISSOCIATION!!

• • if a disorder is found that exhibits the opposite pattern you can make a stronger case for domain specificity!
• • for example, Wernicke’s aphasics have fewer problems with verbs and more severe problems with the production of names for common objects in spontaneous speech
• • so if a patient has damage in Broca’s area and has issues with nouns > verbs, and another patient has damage in Wernicke’s area and has issues with verbs > nouns, then you can make a stronger argument for modular processes.

Question 34

What does PALPA stand for?

Answer 34

Psycholinguistic Assessments of Language Processing in Aphasia

• • it is a box-and-arrow diagram that’s used as an assessment tool (for each box and arrow there is the evaluation of effects of different inputs and outputs)
• • the only psycholinguistically motivated tool for language assessment to date

Question 35

What is the general box-and-arrow process of reading?

Answer 35

[PRINT]
1. abstract letter identification (“yes these are letters”)
2. visual input lexicon (“yes this is a word”)
3. semantic system (“yes this word means something”)
4. phonological output lexicon (“this word is pronounced ____”)
[SPEECH]

– in the case of encountering a nonword that you can still pronounce, there is a direct route from abstract letter identification to speech = Grapheme to Phoneme Conversion.