Exam 2

what are the parts of the auditory pathways and what do they do?

outer ear - collects sound waves

middle ear - transforms sound waves into vibrations of the bone structure

inner ear- transforms compressional wave into nerve impulses

auditory input reaches primary auditory cortex about…

10-15ms after stimulus onset

what is cortical deafness

when a patient has a lesion in the auditory cortex that prevents them from hearing at all

what is amusia

when a patient has a problem with sound and rhythm perception but not with speech perception

environmental sound perception and word perception are…

dissociated

what is an environmental sound problem disorder

auditory aphasia

what is a problem with word production

pure word deafness

where are the lesion sites for pure word deafness, auditory agnosia, and amusia?

PWD - left hemisphere

AA - bilateral

amusia - right hemisphere

what is particularly important for speech?

audiovisual integration

what are the possible pathways for audiovisual integration

1. information first comes from subcortical structures

2. key sensory regions and key association areas feedback and feedforward communication

brain regions engaged by audiovisual integration depend on…

stimulus complexity

there might be differences in the regions that process…

simple auditory, complex speech, and complex nonspeech

describe the lichtheim model

has 3 main centers:

1. A = auditory word center

2. M = motor word center

3. B = concept center

How are the areas of the Lichtheim model connected?

1. A → M: Repeating words you hear (speech repetition)

2. B ↔ A: Understanding language (linking meaning to sound)

3. B ↔ M: Speaking from thought (e.g., generating sentences)

describe the Hickok and Poeppel dual stream model

two pathways project from the phonological network

• “ventral stream” maps sound onto meaning → Helps you recognize words, understand sentences, and get the message

• “dorsal stream” maps sound onto action → Important for speech repetition, learning new words, and speaking clearly

starts in the STG and then goes their respective ways

explain the hierarchical organization of early cortical stages of speech perception

1. the dorsal STG carries out fairly simple spectrotemporal analyses

2. the mid-posterior lateral STG represents subphonemic features and feature combinations

3. the mid -posterior STS represents individual phonemes and the sequential phonological structures of whole words

the processing hierarchy operated not only in…

a bottom-up manner, but also in a top-down manner that is influenced by prior knowledge and expectations

explain the bilateral organization of early corticla stages of speech perception

both hemispheres respond to speech

either hemisphere can process speech fairly well by itself

what is the asymmetric sampling in time (AST) hypothesis

LH dominance for rapid changes of ~20-80ms which is ideal for processing very brief aspects fo speech (eg, cues for place of articulation)

RH dominance for slower changes of ~150-300ms which is better for processing longer aspects of speech (syllabic structure)

explain the lemma model of lexical selection

two stages:

1. selecting the lemma

   • A lemma is the abstract form of a word.

   • It has meaning and grammar, but no sound yet.

2. retrieving the lexeme

   • Now your brain moves to the lexeme — this is the sound/phonological form of the word.

   • this is what you need to actually say the word out loud

what is the flow of the lemma model

Processing stage	cortical region	time course
lexical concept retrieval and selection	retrieved from ATLs (especially left); competitions resolved by left IFG	200-250ms
lemma retrieval and selection	lemmas for object nouns retrieved from varied sectors of left MTG & ITG; competitions resolved by left IFG	200- 290ms
phonological code retrieval	left pSTG	300-360ms
syllabification	left pIGF (especially BA44)*part of Broca’s area	355-455ms
phonetic encoding	left BA44, ventral premotor cortex, anterior superior insula	455-600

what is the DIVA model

computation model that explains how your brain plans and controls the movements of your mouth and vocal tract to produce speech sounds.

what are the three key subsystems

1. speech sound map (SSM)- the planner

• Located in the left premotor cortex and Broca’s area.

• Contains stored motor programs for speech sounds (like "buh" or "ee").

• When you want to say a word, this area is activated first.

2. feedforward control system- the habit system

• These are pre-learned movements for speech.

• Based on past experience and practice.

3. feedback control system- the error checker

• There are two feedback loops:

  • Auditory feedback: You listen to your own voice and check if it sounds right

  • Somatosensory feedback: You feel how your mouth and tongue are moving

what are the step-by-step speech processes in the DIVA model

1. activate a speech sound

2. send motor commands

3. monitor with feedback

According to the Dual Stream Model, the “sensorimotor interface” resides in

a. The posterior inferior frontal gyrus

b. The posterior middle temporal gyrus

c. The anterior superior temporal gyrus

d. The area Spt

e. The inferior temporal gyrus

d. The area Spt

The DIVA model posits the existence of

a. A feedforward and a feedback control system

b. A feedforward control system and a feedback production system

c. A feedforward control system and a conceptual interface

d. A feedback control system and production biases

e. None of the above

a. A feedforward and a feedback control system

Thanks to neuropsychology we know that

a. Perception of speech can be selectively impaired (vs. other sounds)

b. Production of speech can be selectively impaired (vs. comprehension)

c. Dysarthria can take different forms

d. Perception of speech can be selectively impaired (vs. production)

e. All of the above

e. All of the above

characteristics of visual signals in the brain

no redundancy in the eyes

information from one side goes to contralateral side

slower than auditory signals

you can understand written language to a certain point of error

we process through the Gestalt and not stroke by stroke

the attention we need to place on reading is very focal → need to make lots of eye movement

we cannot break symmetry of letters

language is ___, reading and writing are ___

language is ___, reading and writing require ____

universal, not

spontaneous, formal training

reading is a ____ that recycles a part of our visual system in order to access ____ through our vision

cultural invention, linguistic representations

when do we start to have activity in our occipital cortex?

around 80ms and the activity moves to the more frontal regions then back to the occipital regions

what is the pattern of auditory and visual processing once getting to higher processing (200ms onward)

the pattern of activation is very similar once getting to higher order processing

what is the local combination detector (LCD) model

increasing RF size of cells → greater spatial coverage of letters and words

increasing combinations of visual features → greater complexity of representation

what is the hierarchy of coding in the LCD model

points → bilateral LGN

lines → bilateral V1

letter fragments → bilateral V2

case-specific letters → bilateral V4

abstract graphemes → bilateral V7

bigrams, trigrams, quadrigrams, etc → left occipito-temporal sulcus

hierarchical coding in the ventral OT cortex, LH regions of interest

as the sites became more anterior, the signals elicited by less word-like stimuli gradually dropped off, whereas those elicited by more word-like stimuli stayed relatively strong

hierarchical coding in the ventral OT cortex, RH regions of interest

no evidence for a hierarchy

hierarchical coding in the ventral OT cortex, bilateral lingual cortex

showed larger activations for false-fonts than for real-letters stimuli, which did not differ

hierarchical coding in the ventral OT cortex

more activation for words → quadrigrams → bigrams → frequent letters → infrequent letters → false fonts

the visual word form area (VWFA)

altered activation is consistently found in functional brain studies of DD and even pre-readers at risk for developing DD

children with DD appear to show…

not only hypoactivation, but also atypical neural tuning: lack the typical posterior-to-anterior gradient and fail to show sensitivity to orthographic familiarity

VWFA in bilinguals…

the acquisition of multiple writing systems can tune the visual cortex differently in bilinguals, sometimes leading to the emergence of cortical patches specialized for a single language

the location in visual cortex that is reorganized to support literacy is likely determined by…

preferences for foveal signals

predisposition for certain visual features

the presence of long-range white matter connections to requisite visual and language regions

every cultural object must find its

“ecological niche” in the brain → a circuit whose initial role is quite close, and whose flexibility is sufficient to be reconverted to this new use. each circuit has intrinsic properties that make it more or less suitable for its new use, and give cultural objects universal traits

the site of the VWFA is ideally suited to represent the spelling patterns of printed words because

it is apparently designed to register complex combinations of spatially fine-grained shapes, and

it has especially rich connectivity with the circuitry for processing spoken language

as ___ enhanced the ____ evoked by writing, it induced a small competition with ___ at this location, but also broadly enhanced visual responses in ____

literacy, left fusiform activation, faces, fusiform and occipital cortex

reading aloud pseudowords like blicket requires the _________

grapheme-phoneme conversion route

Reading aloud regular words like leg can be done by using either the _____ or a ___ that includes the ___ and ___ lexicons as well as the ___.

grapheme-phoneme conversion route, central route, orthographic, phonological, semantic system

Reading aloud irregular words like yacht can only be done by using the ___, but there is controversy about whether their proper pronunciation requires prior activation of their ____.

central route, meaning

after the ___ of a written word has been adequately processed in the _____ access to its ____ is enabled by a complex ____ and access to its _____ is enable by an equally complex but more ________

visual form, ventral occipitotemporal stream, pronunciation, perisylvian network, meaning, inferior temporal-parietal-frontal network

Writing pseudowords like blicket requires the_____ conversion route.

phoneme-grapheme

Writing regular words like leg can be done by using either the ___ conversion route or a ___ route that includes the ____ and ____ lexicons as well as the ___ system.

phoneme-grapheme, central, phonological, orthographic, semantic

Writing irregular words like yacht can only be done by using the ____ route, but there is controversy about whether the proper spelling of these words requires prior activation of their _____.

central, meaning

alexia

reading disorder with two subcategories

pts who cannot even recognize single letters → lesion to early visual areas

pts who cannot read whole words → lesion to the vwfa

phonological dyslexia

worse on pseudowords than real words → lesions of the dorsal route

surface dyslexia/dysgraphia

worse on irregular words than on regular words and pseudowords → lesions of the ventral route

deep dyslexia/dysgraphia

impaired on pseudowords as well as real words, with errors often being semantic and worse for abstract items

Which syndrome is characterized by worse reading performance on pseudowords than real words?

a. Surface dyslexia

b. Phonological dyslexia

c. Phonological dysgraphia

d. Surface dysgraphia

e. Deep dyslexia

b. Phonological dyslexia

How does the theory of neuronal recycling propose the development of the VWFA?

a. It posits that the VWFA develops early in life solely for visual perception tasks.

b. It argues that the VWFA is a product of genetic mutations related to language.

c. It claims that the VWFA emerges spontaneously in individuals with high linguistic abilities.

d. It suggests that the VWFA develops thanks to specific linguistic experiences.

e. It suggests that the VWFA evolves gradually during pregnancy

d. It suggests that the VWFA develops thanks to specific linguistic experiences.

semantic memory

focuses on the memory component dissociated from event information

semantic knowledge

focuses on information processed conceptually, as opposed to perceptual processing that occurs following external stimulations

semantics

takes a linguistic perspective, highlighting a close connection with lanugage

turing test

does being able to manipulate symbols mean you have semantic knowledge

if a person can’t distinguish between a person or a LLM, then the LLM passes the turing test

chinese room argument

semantic understanding goes beyond mere symbols manipulation

if someone gets a question, can find the answer, and spit back out the answer, do they have semantic knowledge?

what does it mean to be semantically corect?

correct with respect to our semantic memory → I can form a meaningful representation

correct with respect to lexical semantic → I can form a representation of the meaning

coreferential terms

different expressions (words or phrases) that refer to the same thing

synonyms

two words that mean kind of the same thing

colexification

one word in a language expresses multiple related meanings — meanings that other languages might express using different words.

polysemy

one word has multiple related meanings.

homophone

when two words have the same phonological pronunciation but are written differently

homographs

when two words are written in the same way but have two different phonological pronunciations

homonyms

when a word has the same spelling and pronunciation but mean two different things

amodal symbol models

concepts consist of abstract symbols that are represented in a semantic system completely separate from modality-specific systems for perception and action.

grounded cognition models

concepts are anchored in modality-specific systems, such that understanding word meanings involves activating high-level perceptual and motor representations.

the content of semantic knowledge is accessible via

stimuli of ANY modality

agnosia

disorder of sensory processes that results in an inability to correctly recognize or interpret objects, faces, or sensory stimuli, despite intact sensory functions.

aphasia

language disorder that affects a person's ability to understand, speak, read or write, following a brain injury, and can lead to communication difficulties

central semantic deficit

deficit in semantic representations vs disorder preventing access to information or production of the response (i.e., the processes acting on the representations)

Given the heterogeneity of the means by which semantic knowledge can be accessed, when assessing semantic memory it is necessary to exploit a rich set of tasks.

categorization of semantic features

motor-perceptual features → apprehended via sensorimotor systems

conceptual features → learned and/or resulting from the combination of at least two perceptual characteristics

words with auditory features (alarm, etc) activate….

secondary auditory cortices

differential weighting hypothesis

category-specific deficits arise from damage to regions that represent modality-specific information especially important for the given category.

distributed domain-specific hypothesis

category-specific deficits arise from damage to regions that represent information for evolutionary important categories.

where are different features represented: color and shape features

ventral temporal

where are different features represented: motion

lateral temporal

where are different features represented: motor

parietal and frontal

where are different features represented: auditory

superior/middle temporal

where are different features represented: olfactory/gustatory

orbitofrontal

where are different features represented: taxonomic vs thematic

ATL, AG

category specific deficits: animal deficits

bilateral ventral and medial sectors of the temporal lobe

category specific deficits: fruit and vegetable

unilateral left mid-fusiform gyrus

category specific deficits: tool deficits

unilateral left lateral temporal (pMTG), inferior parietal (aIPS/SMG), and/or inferior frontal (vPMC) regions

while semantic representations are distributed across the cortex, the integration of these representations take place in dedicated multimodal hubs

convergence zones, transmodal semantic hub, higher order hubs

what is the N400

electrophysiological component measured in the EEG which usually occurs around 400 milliseconds after the presentation of

N400 amplitude is strongly correlated with a measure of

word expectancy (cloze probability)

the N400 increases in amplitude when the stimulus is

unexpected, inconsistent, or does not match the semantic context.

therefore the N400 is often interpreted as a measure of

semantic integration, reflecting the ease with which the brain integrates a word or concept into the current semantic context.

adjective-noun combination show…

increases activity in the left anterior temporal lobe (ATL) between 200 and 250 ms after noun onset. Approximately 200 ms later, another increase in activity often occurs in the ventromedial prefrontal cortex (vmPFC)

ATL activity elicited by the second word of a sentence appears to reflect the

proportion of features contributed by the first word to the combined set of features of the entire sentence.

AG (angular gyrus) reaches a significant peak around

170 ms after the appearance of a visual word and is sensitive to the number of arguments that the word contains. For example, a transitive verb elicits greater activation than an intransitive verb

PTL (posterior temporal lobe) appears to be involved in

processing based on syntactic structure. For example, verb phrases elicit greater activation than noun phrases (200ms)

ATL (anterior temporal lobe) does not only

link features between words (red boat), but also the characteristics which define the concepts (200ms)