Neurobiology of Language

Question 1

Power of language is based on the ability to

Answer 1

combine elements from memory in novel ways

Question 2

how do sound patterns in babies change

Answer 2

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

Question 3

when is there an explosion of word acquisition in babies?

Answer 3

from 16-30 months, babies gain hundreds of words

Question 4

how can we study neurobiology of lanugage?

Answer 4

eeg - structural
fmri- functional
ecog - typically done with epileptic patients
diffusion tensor imaging - diffusion of water to map connectivity between brain regions

Question 5

language has the following

Answer 5

phonemes - sounds
morphology- how parts of words are put together
syntax- grammatical structure
semantics- meaning

Question 6

what kind of studies were used to determine how the brain perceives a continuous auditory signal and segments it into sounds, words, and sentences?

Answer 6

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

Question 7

what is the McGurk effect?

Answer 7

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

Question 8

what is the phonemic ambiguity resolution

Answer 8

phonemes can be ambiguous, so the future is used to retroactively disambiguate it

phoneme perception involves feedforward and feedback cortical connections

Question 9

how does the brain separate speech vs noise auditory inputs? how did they find this out?

Answer 9

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

Question 10

How is the organization of language understanding similar to other systems in the brain?

Answer 10

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

Question 11

What’s different about words vs. nonwords?

Answer 11

Semantic meaning
- in temporal lobe
- regions of brain further out of cortex are important for meaning

Question 12

How does rhythm affect language understanding?

Answer 12

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

Question 13

what is Neural entrainment and what effect does it have to people’s social interactions

Answer 13

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

Question 14

what is the aphasia disorder of language?

Answer 14

impairment in language production/comprehension caused by brain injury

Question 15

What is wernicke’s aphasia/fluent aphasia?

Answer 15

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”)

Question 16

what is Broca’s aphasia

Answer 16

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

Question 17

what is Transcranial magnetic stimulation (TMS) and how was it used to see how broca’s area is affected

Answer 17

magnetic waves hit on certain areas of the brain

TMS virtual lesion to broca’s area disrupts speech production

Question 18

what is the classical model of language and the brain

Answer 18

1. Information about sound is analyzed by primary auditory cortex and transmitted to wernicke’s area
2. Wernicke’s area analyzes sound info to determine what word was said
3. Information from wernicke’s area is transmitted through the arcuate fasciculus to broca’s area
4. Broca’s area forms a motor plan to repeat the word and send that info to motor cortex
5. Motor cortex implements the plan, manipulating the larynx and related structures to say the word

Question 19

what is the arcuate fasciculus?

Answer 19

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

Question 20

what are some of the challenges to the classical model for language

Answer 20

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

Question 21

what are some structural differences in bilingualism?

Answer 21

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