Flashcards in Language Deck (46):
What's unique about Chinese readers?
They show more bilateral activation while reading even when they're reading in English.
What is phonetic and surface dyslexia?
Phonetic: have trouble pronouncing words when reading them. Can still read symbolic script (Japanese have two scripts and they can still read the symbolic one).
Surface: Have trouble distinguishing between homophones. They can still read the phonetic script.
Below the whole word (parts of a word or not including words)
What does the ventral stream do?
Processes signals for comprehension (speech recognition).
What does the dorsal stream do?
Maps acoustic speech signals to frontal lobe articulatory networks (speech perception). This includes translating acoustic speech signals into articulatory representations in the frontal lobe, essential for speech development and normal speech production.
Which stream is bilateral and which is more lateral?
Ventral is bilateral and dorsal is lateral.
Superior temporal gyrus (Wernicke's area)
What are two reasons that STG is thought to not be solely involved in speech perception?
Damage to the superior temporal gyrus (Wernicke's area) does not inhibit the ability to perceive speech sounds and destruction of it does not impair the ability to understand speech. It only affects the ability to produce it.
Speech recognition circuits may share neural tissue with the STG.
Is the ability to discriminate syllables and the ability to understand words associated?
No. It's doubly disassociated.
What is the difference between the dorsal and ventral circuits?
Dorsal stream is related to speech perception and ventral to speech recognition.
What areas of the temporal lobe are used in speech recognition?
Superior and middle
What areas does the dorsal stream include?
Posterior frontal and posterior dorsal temporal and parietal operculum
Superior temporal sulcus
Sylvian fissure at the parietotemporal boundary
anterior inferior temporal sulcus
anterior middle temporal gyrus
posterior inferior frontal gyrus
What does the earliest stage for cortical speech involve?
spectrotemporal analysis in the auditory cortices bilaterally in the supratemporal plane.
What is spectrotemporal analysis?
Analysis of volume of audio frequencies
What is audio frequency?
Explain the stages of speech processing and brain areas involved
It's known as the dual-stream model
Spectrotemporal computations with phonological-level processing in the middle to posterior portions of the STS with weak left-hemisphere bias diverges to dorsal and ventral pathways
Dorsal pathway: maps sensory or phonological representations onto motor representations
Ventral pathway: maps them onto lexical conceptual ones.
What area is involved in spectrotemporal analysis?
Speech perception starts here
Dorsal areas of the superior temporal gyrus (STG)
It's in the thumb crease area of the temporal lobe and communicates directly with a ventral (STS) and posterior area (Sylvian fissure)
STG to STS is part of phonology at a lexical level
What area is involved in phonological processes?
Posterior half of the STS.
It's located in the middle of the thumb, ventrally and somewhat posteriorally (half way back from) the STG.
It communicates with the STG, Sylvian fissure, and posterior and inferior portions of the temporal lobe.
STS may map whole words
What areas correspond with the lexical interface to link phonological and semantic information?
Posterior inferior portions of the temporal lobe
located at the bottom of the brain and meeting the STS.
Communicates with the STS and anterior inferior portions of the temporal lobe.
Contains the visual word form area (sort of)
What areas correspond to the proposed combinatorial network of the ventral stream?
It's the semantic hub as is supported by semantic aphasia evidence.
Anterior inferior portions of the temporal lobe
Located towards the bottom but not quite all the way and up by the thumb knuckle.
Communicates with the posterior inferior portions of the temporal lobe and the Broca's area.
Posterior area of the posterior inferior temporal lobe communicates with it to move to a conceptual system
What areas correspond to the sensorimotor interface?
Sylvian fissure at the parietotemporal boundary (Spt)
It's located posterior to the STG with some small gap.
It communicates with the STG, STS, and anteror locations in the frontal lobe including Broca's region, dorsal premotor cortex site,
What areas are involved in the articulatory network?
Broca's region (located above the thumb knuckle) and the dorsal premotor cortex located even further dorsally.
Broca's area communicates with the anterior inferior temporal cortex and both communicate with the Sylvian fissure
Is there one pathway or multiple paths to lexical access and are they parallel or serial?
And is it lateral or bilateral?
Multiple, bilateral, parallel paths
What supports the idea of redundant bilateral computational mechanisms?
Behavioral evidence that people can still understand speech despite degradation.
Anesthetizing the left hemisphere still allows some access.
What bilateral areas show activation while listening in an MRI?
Dorsal STG and STS
What is phonetic encoding?
Processing syllables. d-ah-g for dog.
Explain the diagram of the speech pathway.
Spectrotemporal analysis (Dorsal STG, bilateral) Phonological network (Mid-Post STS, bilateral) Sensorimotor interface (Input from other sensory modalities, Parietal-temporal Spt, lateral) Articulaory network (pIFG, PM, anterior insula, lateral Combinatorial network (aMTG, aITS, lateral?) lexical interface pMTG,PITS, weak lateral), back to STS or Conceptual network (widely distributed) Articulatory Network
Vibration of the vocal cords
Continuous vs explosive?
Manner of articulation or how the air moves
What is the kinematics of the mouth?
Place of articulation.
How is it clear that it's difficult to rehear ignored sounds?
When slowly switching from rake to lake, Japanese comprehenders show no effect but English speakers do.
I think this was described as an attractor space or magnet. We don't hear ambiguity, we just switch all of a sudden.
When do babies switch from being universal listeners to preferential listeners?
Between 8-10 months. Before 8 months, babies look at the new sound in ra ra ra ra la ra ra ra, but after that, Japanese babies decreased looking and English babies increased.
How do babies learn sounds?
Parents exaggerate salient sounds or praise salient babbling or both
Hebian, statistical learning is likely too slow.
What is the McGurk effect?
Pairing the audio of one sound with the visual of another sound. People follow the visual signal.
What is the Feedforward Control Subsystem
Speech Sound Map (left Frontal Operculum) to Cerebellum or Articulatory Velocity and Position Maps (motor cortex) to articulatory musculature via subcortical nuclei.
Note: If it goes to the cerebellum it proceeds to the Articulatory Velocity and Position Maps (motor cortex)
Note: The Speech sound map forms phonemes.
What is the Feedback Control Subsystem?
Auditory feedback via subcortical nuclei:
Auditory State Map (Sup Temporal Cortex) to Auditory Error Map (Sup. Temporal Cortex) to Articulatory Velocity and position maps
Somatosensory feedback vis subcortical nuclei:
Somatosensory Sensory State Map (Inf. Parietal Cortex) to Somatosensory Error Map (Inf. Parietal Cortex) to Articulatory Velocity and Position Maps.
Speech Sound Map (Left Frontal Operculum) to Auditory Error Map or Somatosensory Error Map) This sends sensory expectations to these errors that are also receiving feedback.
What is the somatosensory target region all about?
Looks like a proprioceptive signal from the tongue that can predict the consequences of movement.
What does DIVA stand for and what is its purpose?
Directions Into Velocities of Articulators seeks to learn to control movements to create phonemes through a babbling cycle.
It babbles to learn what sounds go with which movements and then can match those movements to sounds it hears.
Why are feedforward and feedback systems necessary?
Feedback alone isn't fast enough. I think this is the same principle as with motor. The whole movement has to be planned.