Neurobiology of Language Flashcards
(21 cards)
Power of language is based on the ability to
combine elements from memory in novel ways
how do sound patterns in babies change
change in accordance to their native language
ex: french babies have a more intense cry sound at end of sound reflecting sound of french accent
when is there an explosion of word acquisition in babies?
from 16-30 months, babies gain hundreds of words
how can we study neurobiology of lanugage?
eeg - structural
fmri- functional
ecog - typically done with epileptic patients
diffusion tensor imaging - diffusion of water to map connectivity between brain regions
language has the following
phonemes - sounds
morphology- how parts of words are put together
syntax- grammatical structure
semantics- meaning
what kind of studies were used to determine how the brain perceives a continuous auditory signal and segments it into sounds, words, and sentences?
STUDIES: ecog are common to determine this
- electrodes are implanted on the temporal lobe to record activity from the cortical areas
FOUND: different neurons in the primary auditory cortex responds selectively to distinct phonemes
what is the McGurk effect?
effect of what you are seeing overriding what you are hearing
tells us that visual processing has an effect on how language is understood; multisensory integration of information
it isnt solely a bottom up understanding
what is the phonemic ambiguity resolution
phonemes can be ambiguous, so the future is used to retroactively disambiguate it
phoneme perception involves feedforward and feedback cortical connections
how does the brain separate speech vs noise auditory inputs? how did they find this out?
FOUND: the left hemisphere is more sensitivie to speech sounds than the right hemisphere.
STUDY: participants listened to nonsense noises/tones and speech sounds (reversed, pseudowords, and words). fmri scans showed regions of the brain involved in a hierarchical processing stream for speech processing
How is the organization of language understanding similar to other systems in the brain?
understanding language also gets sequentially more complex in a hierarchical manner, much like the visual cortex
basic units of sound → tonal quality → things with letters (speech-like sound) → actual language
What’s different about words vs. nonwords?
Semantic meaning
- in temporal lobe
- regions of brain further out of cortex are important for meaning
How does rhythm affect language understanding?
This was studied using eeg; looked at rhythmic patterns in language. Uses this info to separate different parts of spoken sentences (decode and parse linguistic info)
Different frequencies in different kinds of sounds (syllables vs words vs phrases) can help determine which is which
what is Neural entrainment and what effect does it have to people’s social interactions
frequencies of neuronal activity present in brain mirror frequencies present in speech
Neural oscillations may provide mechanisms to segment and decode continuous speech input
Sound of a vowel is determined by the pace of speech. Ex: tak vs taak depending on fast vs slow speech rate
Brainwaves align between speaker and listener. Neural coupling underlies successful communication
Stronger entrainment associated with better understanding of speaker’s story
what is the aphasia disorder of language?
impairment in language production/comprehension caused by brain injury
What is wernicke’s aphasia/fluent aphasia?
language comprehension is impaired
Fluent aphasia (word salad)- can verbalize words that sound right with a rhythm that is consistent, but what they are saying is not completely aligned with the question asked. Patient did not seem to realize he wasn’t making the best sense. Patient also seemed to fall back on the same words
Wernicke’s area - speech comprehension (“sensory area”)
what is Broca’s aphasia
speech production is impaired (“motor area”)
Patient is able to understand questions and can answer correctly, but has difficulty getting the words. Grammar is poor and words are mostly nouns
Language production (articulation) is the most difficult
Slow halting effortful speech
Left inferior frontal gyrus, “broca’s area,” is key region supporting language production. also seen in deaf individuals
what is Transcranial magnetic stimulation (TMS) and how was it used to see how broca’s area is affected
magnetic waves hit on certain areas of the brain
TMS virtual lesion to broca’s area disrupts speech production
what is the classical model of language and the brain
- Information about sound is analyzed by primary auditory cortex and transmitted to wernicke’s area
- Wernicke’s area analyzes sound info to determine what word was said
- Information from wernicke’s area is transmitted through the arcuate fasciculus to broca’s area
- Broca’s area forms a motor plan to repeat the word and send that info to motor cortex
- Motor cortex implements the plan, manipulating the larynx and related structures to say the word
what is the arcuate fasciculus?
is a bundle of axons that connects the temporal cortex and inferior parietal cortex to locations in the frontal lobe.
connects Broca’s and Wernicke’s areas, which are involved in producing and understanding language
what are some of the challenges to the classical model for language
Lesions to broca’s area can impair both language production and comprehension.
Only 85% broca;s aphasia have lesions to broca’s area
Only 50-60% of patients with lesions to broca’s area have broca’s aphasia. Can be caused by broader lesions (frontal cortex, insula)
Traditionally defined as cortical dysfunction but can result from subcortical brain lesions (basal ganglia, white matter tracts- superior longitudinal fasciculus, thalamus)
Severing white matter tracts with cortical sparing results in severe non fluent aphasia so it could be important how different brian areas talk to each other
Lack of neural distinctions between language production and comprehension
Lesions to broca’s area can impair both language production and comprehension
Penfield’s experiments shows that stimulation of broca’s and wenicke’s area disrupts language production
what are some structural differences in bilingualism?
In an experiment, they compared brains of monolinguals, early, and late bilinguals.
- Saw there are more cell bodies and cortical tissue in left interior frontal gyrus (IFG) in both early and late bilinguals
- Early bilinguals have thicker IFG in right hemisphere compared to late bilinguals
