Chapter 13: Neurolinguistics Flashcards
Neurolinguistics
The study of how language is represented in the brain
The brain is composed of how many nerve cells?
10 billion
Each neuron can be directly linked with up to ___ others
10,000
Which brain structures are shared by almost all animals?
The lower brain structures that are closer to the spinal cord
The cortex
The outermost layer of the human brain
Absent in some reptiles
The cortex is ____ on itself to increase ____
Folded; surface area
Sulcus
The inward part of a cortical fold
Gyrus
The outward part of a cortical fold
Fissures
Deep sulci
Longitudinal Fissures
Separate the cerebral hemispheres
Corpus Callosum
Bundle of nerve fibres cerebral hemispheres
T/F
Left and right cerebral hemispheres are anatomically and functionally separate
True
Cerebral hemispheres control which functions of the body?
Contralateral functions
= those on the opposite side
The Left hemisphere controls
Analytical abilities
E.g. arithmetic
The Right hemisphere controles
Holistic tasks
E.g. recognition of faces
Who is left-lateralized for language?
Most right-handed people
Removal of a right-handed person’s left hemisphere causes
An inability to process complex syntactic pattern, although they retain some comprehension ability
Removal of a right-handed person’s right hemisphere causes
Difficulty understanding jokes and metaphors
Left-handed people tend to be less ____ for language
Lateralized
The hemispheres are divided into ____
Lobes
Where is the central sulcus?
Behind the frontal lobe and in front of the parietal lobe
Where is the Sylvian fissure?
Above the temporal lobe, separates it from the frontal/parietal lobes
Where is the occipital lobe?
Behind the parietal lobe
Is not separated by a fissure
What poses a special challenge for the neuroscience of language?
The absence of straightforward animal models
Autopsy Study
- A living patient is studied, and after death the brain damage is recorded
Computerized Axial Tomography (CT scan)
Uses X-rays to provide a 3D static image of the brain to identify lesions and tumours
Positron Emission Tomography (PET)
Uses a radioactive traced to track glucose absorption in the brain, which is higher in areas of activity
Functional Magnetic Resonance Imaging (fMRI)
Uses a powerful magnet to measure blood deoxygenation, with no radioactive tracer
Magnetoencephlography (MEG)
Uses sensors to measure tiny magnetic fields on the surface of the scalp
Non-invasive
Good spatial and temporal resolution
Which hemisphere is primarily responsible for language?
The left hemisphere
When is Broca’s area activated?
During speech
When are the occipital lobe and angular gyrus active?
During reading
How does processing an L2 affect the brain?
It activates a wider variety of cortical areas than an L1
= L2 processing involves diverse mental processes
Dichotic Listening
Presents different auditory stimuli to each ear
Finding from dichotic listening
A right ear advantage arises for words, numbers, morse code
A left ear advantage arises for melodies and environmental sounds
Split-brain experiments
Severing the corpus callosum (separating the hemispheres)
Demonstrate that the right hemisphere is mute
Eg. a blindfolded patient can name an object in their right hand, but not their left
Aphasia
The loss of language ability resulting from brain damage
Usually caused by a stroke
What is the prevalence of aphasia?
More than 1 million people in North America
Equally common in men and women
More likely to occur after 50
Non-fluent (motor) Aphasia
Caused by damage to the frontal lobe
- Global and Broca’s aphasia
Global Aphasia
Most severe form of non-fluent aphasia
Damage to the frontal lobe
Results in muteness
Broca’s Aphasia
Type of non-fluent aphasia
Damage to the lower posterior portion of the left frontal lobe (Broca’s area)
Results in dysprosody (abnormal intonation) and phonemic paraphasias (producing segments rather than full words)
Dysprosody
The absence of normal sentence intonation
Phonemic Paraphasias
The substitution of a word with a nonword that preserves part of its segments
Broca’s Aphasics tend to omit
Function words and inflectional affixes
= deep deficit, not just articulatory
Telegraphic speech
Speech reduced to nouns and verbs
Broca’s Aphasics tend to have difficulty
- Judging grammaticality
2. Interpreting passives
Broca’s Aphasics still have control over
Muscles used in speech production
Broca’s area does not seem to be involved in ____ relationships in language
Semantic
Broca’s aphasics are ___ aware of their language defecit
Typically
Fluent (sensory) Aphasia
There is no difficulty in producing language, but the content that is produced is disordered
- Wernicke’s Aphasia
Wernicke’s Aphasia
Damage to the upper posterior portion of the left temporal lobe (Wernicke’s area)
Jargon Aphasia
Severe form of Wernicke’s aphasia
Phonemes are randomly selected
Speech has correct intonation, but few recognizable words
Wernicke’s aphasics lack
Coherent trains of thought
Wernicke’s aphasics have difficulty
Doing sequenced tasks
Eg. buying groceries or doing laundry
Wernicke’s aphsics are ___ aware of their disorder
Not
Acquired Dyslexia
Impairment of reading ability following brain damage
Acquired Dysgraphia
Impairment of writing ability following brain damage
Paragraphia
When writing, Broca’s aphasics often omit the letters corresponding to sounds they would omit in speech
Broca’s aphasics are ___ at silent reading and ___ when reading aloud
Good; telegraphic
Wernicke’s aphasics have ___ spelling & handwriting and their writing is ____
Unclear and makes little sense
The reading comprehansion of Wernicke’s aphasics is
Severely impaired
When acquired reading and writing deficits occur on their own, they usually follow damage to
The angular gyrus
English orthography requires what 2 kinds of knowledge?
- Spelling-to-sound rules
2. Recognition of whole words
Phonological Dyslexia
Loss of ability to use spelling-to-sound rules
Can only read familiar words
Reading the words ‘ble’ and ‘bug’ rather than ‘blug’ is a symptom of
Phonological dyslexia
Surface dyslexia
Loss of ability to recognize whole words
Overregularize the pronunciation of irregular words
Comprehend words by pronunciation rather than spelling
Broca’s aphasics will produce the ___ form of a morpheme rather than the ___
Unrestricted; allomorph
e.g. illegal > inlegal
Deep Dyslexia
Produce words that are semantically related to a word they are asked to read
Eg. mother > father
= evidence for semantic organization of the lexicon
Aggrammatism
The absence of certain grammatical abilities
Occurs in Broca’s aphasics
What words are typically omitted by Broca’s aphasics
it, is, to, a
functional words
Lexical categories
Categories of content words (nouns, verbs, adjectives)
Default Strategy
Used by Broca’s aphasics to help process passives
Treating first NP as an agent
What strategy do Broca’s Aphasics use to find the meanings of reversible passives
Guessing
Eg. The cat was chased by the dog
