TB7- Brain and Language Flashcards
Which side of VF would have an advantage for naming objects?
right VF as left hemishere Dominant for language in most people
which side of VF would a split brain patient not be able to name an object from?
presented to left VF, as their hemispheres cannot communicate and language is in the left
dichotic listening tasks usually have a _____ ear dominance?
right, as language in left hemisphere (this is for right handers)
Young and Ellis found a ____ visual field advantage for word recognition percentage correct and ____
RIGHT VF advantage for % correct items and reaction times
where is Wernickes area?
superior temporal gyrus STG
Where is Broca’s area?
inferior frontal gyrus (near motor cortex)
What is Broca’s aphasia? (non-fluent aphasia)
symptoms:
speech hard to initiate, laboured and hakted
may only be able to say one word eg tan
meaning preserved but some comprehension impairments
also sometimes see agrammatism and mild articulatory, OR just articulatory problems.- different problems
What is Wernicke’s aphasia? (otherwise known as sensory or receptive aphasia)
symptoms: fluent,articulated speech often nonsensical
impaired spoken language understanding
organising thoughts difficulty
damage usually more extensive
are parietal and temporal dorsal or ventral? Scott
dorsal= parietal ventral=temporal ventral route (auditory to temporal pole) is involved in understanding meaningful sounds/intelligible speech. Meaning is anterior regions, but dorsal route responds to unintelligable (played backwards) - SCOTT
which route does sound repetition engage?
dorsal route- doesnt necessarily activate meaning
which route do familiar words engage?
ventral route
naming familiar objects enages which route/s?
BOTH! meaning would be automatically activated (ventral route) and the phonological form needs to be retrieved for naming (dorsal route)
which routes are involved in the stroop task when naming the font colour?
both routes- dorsal route has the colour name to be pronounced to say it, but the ventral route is activating a different colour- the actual colour seen. TF CONFLICT between them
what is a visual lexicon?
we extract it from words, and is the visual word form about the shapes of letters. most familiar words have an orphoograhic representation
where is global recognition of words happening?
right visual field/left hemisphere (young&ellis)
orthographic vs phonological form-
orthographic is like ‘cat’, how it is written, and phonological /kat/, how it sounds
in which hemisphere is recognition immediate, and which more serial?
left- immediate (where global is)
right- more serial
what type of processing do we use to read non-words?
serial, cannot use global
Cognitive models of reading- dual route model?
dual route- one route for reading nonwords (grapheme-phoneme conversion) which is independent of visual lexicon and meaning. and route 2 through visual lexicon and semantics to phonology.
(sounding out route and semantic route)
Cognitive models of reading- triangle model?
reciprocal links between phonological word forms, orthographical forms and semantics. more interactive and spreads throughout network.
cogntiive models of reading- how similar are their predictions?
similar, but dual route amended to account for phenomena, adding extra links. in original DR model have to access meaning before output, which doesn’t make sense.
which area responds to words?
in fusiform gyrus (occipitotemporal) VISUAL WORD FORM AREA - responds to upper and lower equally, words more than non-words,eg taxi vs taksi
is in left hemisphere and responds equally to left/right VF presentation
criticism of visual word form area found?
controversial- Price argues also responds to objects so isnt specialised.
fmri study that found VWFA- McCandliss et al
whether presented in left or right VF, activity in the left VWFA responds more strongly to words than consonant strings, suggesting word recognition or identification is in left hemisphere.
Dehaene and Cohen- VWFA specialisation results from learning/reading experience
compared literates, illiterates and ex-literates, looked at how brain changes as a result of training. found VWFA responds little in illiterates but a lot in literates. for those with no experience, VWFA doesnt respond to letters but does to faces. Decreases as function of reading experience (more reading>less face activity). same for houses/geometric patterns and opposite with written material.
implications of Dehane and Cohen’s experiment on VWFA?
specialisation results from reading/learning experience. more response in brain to VWFA as get more experience with reading. TF brain may adapt area originally fror objects/faces, to leters and reading.
supporting research for implications of Dehane and Cohens VWFA experiment on specialisation.
blind readers of Braille and signers have WFA. skilled readers also activate the VWFA when listening to words
triangle model interpretation of VWFA specialisation
specialisation leads to establishing stronger links between phonological and orthographical word forms, so when you activate one form the others also activated especially in highly skilled readers.
when else is the VWFA activated apart from reading aloud?
sounding out non words still does (uses dorsal route)
if reading familiar words silently ventral stream activates it
reading aloud engages both streams
Developmental Dyslexia description
difficulty in reading (below age expectancy)
see no issues speaking, has hereditary component, is a phonological impairment (decomposing words into sounds)
not recognised til child starts reading, as with sounds they use global cues/reps. vocab may be bit poorer.
where are dyslexics deficits seen in tasks?
non word repetition
naming pictures (expressive vocab)
and phonological working memory tests
(main issue is in mapping orphology and phrenology)
what do fMRI studies of dyslexic brains find?
deactivation in reading network, especially the phonological route. white and grey matter volume appear different too (anatomical structures and connection)
acquired dyslexia and dysgraphia (inability to write)
appears due to brain damage/stroke. called central when affect the language processing routes (dorsal/ventral) rather than other sensory function like visual processing.
types of acquired dyslexia (central) and problems they have and damage to which route
types:
surface- issue mapping words to meaning. Ventral damage
phonological- issue mapping grapheme to phoneme. Dorsal damage
deep- issue mapping letters to meaning and phonemes. Damage to both ventral and dorsal
in English, grapheme to phoneme mapping is often irregular, eg
regular- hint, boat, root. follow frequent letter to sound mapping
irregular- break, yacht, pint, do not follow usual rules and irregular pronunciations often lead to regularisation errors in kids
can also be of HF or LF, more errors for LF
surface dyslexia
misreading irregular spelt words (regularisation errors)
words with regular spelling read better, and theres a frequency by regularity interaction.
surface dysgraphia and regularisation errors
show similar to in surface dyslexia eg cough- COFF, spell as would say (regular forms), patients can be semantic dementia patients, like in Graham study where they also struggl most with LF irregular words
whats the main issue that causes surface dyslexia/dysgraphia?
overreliance on DORSAL route due to damage to ventral route (ventral has meaning and dorsal the phoneme conversions. with ventral damaged the brain doesnt automatically access meaning upon seeing written form) which is why they sound out letters.
seen in SD as link of word form to meaning is damaged, but HF words may have some semantic support.with LF irregular words cant acces a semantic rep to see its an exception word, tf they use regular rules
what type of dyslexic would spell pheasant as FEZANT?
surface dyslexic spells it as it sounds
what type of patient couldnt recognise nay and neigh are the same?
phonological dyslexic
describe phonologicaldyslexia
fine visual lexicon/comprehension but cant PRONOUNCE unfamiliar words, they are read as familiar words instead.
short term memory for speech sounds and sund manipulation (phonologica buffer) and impaired grapheme-phoneme conversion in reading and writing.
use global mapping between meaning and pronounciation or a familiar motor plan (dorsal route) but only for familiar words, so heavily rely on ventral route.
where is the phonological buffer?
angular gyrus
deep dyslexia (and same for deep dysgraphia)
cant read nonwords due to dorsal damage. better at reading concrete than abstract words (semantic support for actual items)
visual errors eg signal as single
semantic errors eg finger not arm
visual-then-semantic errors eg favour>sympathy>orchestra
(same errors made in spelling )
theories to explain deep dyslexia
multiple impairments in left reading netword (nonword impairment implies dorsal damage and limited reading with semantic errors implies ventral damage)
explanations-
summation hypothesis says sufficient residual activation from each route can add up to give correct result
right hemisphere involvement argument says it contains some coarse semantic info (poor semantics in right used)
what is semantic memory and where is it held?
concepts with a collection of features about the thing. ANTERIOR TEMPORAL LOBE
theories for conceptual representation- heirarchical
- heirarchical models: collins and quinlan. each has different features getting more specific down the tree. Response times from category verification tasks showed RT increased as nodes went up in the heirarchy
theories for conceptual representation- prototype models
explains why “a penguin is a bird” took longer than other cases…concepts are made of frequent/typical features of typical category members and graded internal structure as a function of similarity to the prototype
theories for conceptual representation- embdied concepts
grounding concepts in body actions and perception (sensory-motor features), everything is linked to how we interact with it. eg JUG, combine perceptual rep (size,shape) witih actions (drink,grab) > activates the planning and execuion structures.
(motor cortex is somatopically organised by body part). action verbs engage motor area.
LINKS TO MIRROR NEURONS
distributed models of semantic memory
dist network organised around sensory-motor functions. networks of features make up categories eg animals. motor features, motion features and object/animal shapes are all stored separately.
JRB category specific impairment
JRB had difficulty understanding and naming specific object categories, and some patients showed opposite. with picture naming and object definition, he did very well with non living objects and badly with living ones.
maybe bcos living things are known more for their sensory-perceptual properties and non living for functions(warrington&shallice)
what brain area does herpes simplex encephalitis tend to affect?
MEDIAL TEMPORAL LOBES. relatively preserved functional knowledge vs sensory/visual feature knowledge for animals and living things.
what are the different ways to explain JRBs category specific deficit in recognition of living things?
- damage to category knowledge, as in heirarchical model. top node being living vs non
- selective damage of sensory features, with knowledge representations clustered as in distributed . most likely to be nb 2 (as semantic impairments are varying and more or less specific)
criticism of distributed model of semantic impairments
.the fact SD/ herpes affects the anterior temporal lobe and can lead to non category specific impairments is an argument against the distributed model
what is SEMANTIC DEMENTIA- symptoms
multimodal deficit in recognition and understanding of words/concepts, with spoken and written word affected, and not category specific. Can be chatty without much meaning.
what does semantic dementia often preserve?
grammar, articulation, episodic memory, spatial/geographical knowledge and executive control
what do picture naming studies over time show about semantic dementia?
they struggle with atypical naming, and lose specificity over time, starting to generalise eg ‘animal’ rather than what type
they lose LF and highly specific concepts first
superordinate and coordinate errors made (hierarchical structure plays a role)
can copy drawings but if taken away features get more generic
what other factors affect retention/loss of meanings in semantic dementia?
- familiarity/frequency
2. age of acquisition (whether learned early or late in life)
Mayberry study “is this a bird?”
categorisation experiments with semantic dementia patients> patients more likely to make errors with an atypical member of the bird category like emu, and also make over-generalisation errors eg butterfly is a bird due to wing feature.
TF typicality of concepts play a role as in prototype theories
surface dyslexia/dysgraphia in SD
many SD patients are surface dyslexics TF have an overrelience on the dorsal stream (regular letter to sound mappings). irregular words have to be learned on a case by case basis needing meaning, TF do worse with irregular words and show regularisation errors like cough>COFF
which theory explains semantic dementia?
HUB AND SPOKE THEORY- the temporal poles form a hub where knowledge of particular aspects of meaning like appearance, use etc, are brought together from different spoke sites and interlinked.
- multimodal integration in anterior temporal lobe
- explains SD
- distributed and convergent nature of conceptual knowledge
- impairment is generic as due to binding issue rather than specific features
TMS study of semantic processing of pictures
TMS during picture naming of high manipulability objects and low manipulability objects eg brush vs lettuce
> Anterior temporal lobe TMS disrupts high and low manip equally so ATL isnt category specific
IPL (inferior parietal lobule) disruption affects high manipulability more
ATL is a convergence zone
what does the LIFG do ?
SEMANTIC CONTROL
- acts in concert with posterior middle temporal gyrus PMTG
- is a convergent zone
- is involved in retrieving,selecting and maintaining sensory info so selects among competitors
fMRI studies on LIFG and PGMT in semantic contol- competitive word generation and understanding, difficult word selection and retrieving demanding words
competitive word generation- compares activity with generating action words more or less associated with presented noun
competitive word understanding- more activity for ambiguous words than unambiguous
difficult word selection- higher activity in LIFG for weak associations
Retrieval of demanding word types- more activity for verbs than nouns and abstract than concrete (imageability)
what does the ATL do in semantic memory?
binds features together
the semantic network has modality specific areas, multimodal areas and control regions.
what is agrammatism?
difficulty forming sentences (grammatical relationships), as in Broca’s aphasia- seen in cookie jar scene. big issue with who is doing what to whom
what is telegraphic speech?
simplified sentence formation with function words omitted and common errors in tense, number, gender (in agrammatism)
TROG- Bishop ( test for the reception of grammar) comprehension
“the girl is chasing the horse” active sentence> little problems seen
“the girl is BEING chased BY the horse” > passive sentence, more impairments seen when need to pay attention to function words
Broca’s area supports understanding of who is doing what to whom
what are reversible sentences?
eg the leopard was killed by the lion- could be either way around, as 2 nouns equally likely to be agents or patients, semantic knowledge isnt helpful) so broca patients struggle and typical adults even have higher RTs
what type of grammatical errors do broca’s patients have?
grammatical relations- prepositions misinterpreted eg the shoe UNDER the pencil is blue, he has a picture OF her to show
overall what do agrammatism patients have problems with, and what do they rely on?
problems with relationships between words, function words, and inflectional endings like -ed, -ing, -s
Instead, base understanding on meanings of individual words, general knowledge and simple word order assumptions
where do the dorsal and ventral language routes come together?
LIFG (Broca’s area)
where is the sentence processing network?
Broca’s area (LIFG) PLUS posterior temporal gyrus (left hem).
lesions in posterior temporal lead to word retrieval/semantic interpretation issues.
THIS NETWORKS ALSO SEEN IN SIGN LANGUAGE ESP COMPREHENSION
Humphreys and Gennari sentence processing network imaging study
production task easy/hard, comprehension task easy/hard. > Core shared network was LIFG, PMTG and stronger response to hard cases. Production also recruits dorsal route places.
Tettamanti et al imaging study-
activity for each sentence relative to control sentence, and more activity in leg area on motor strip for leg action sentence, etc
LIFG and PMTG plus motor strip/parietal regions active.
Theories for the role of Broca’a area LIFG in sentences
1- syntax (harder relationships between words)
2-competitive processes between alternatives
3- working memory
study on whether LIFG/PMTG has a more general function
involved in more difficult word procesing, competitive word generation, ambiguous word interpretation.
May be a general regulatory function of semantic info, selecting and managing alternatives when its not automatic
Which side are brocas and wernickes on?
Left! Language
what did sperry and gazzaniga’s split brain study find?
if present info to the left hand or VF, they cannot answer as processed by right hemisphere
told us language is left lateralised.
what are brocas and wernickes areas near to?
broca- motor area (production)
wernicke- auditory cortex (comprehension)
effecr of word length on recognition time?
not much- suggests letters in the word are processed in parallel
word superiority effect?
we recognise letters quicker when within a word or a nonsense word which follows combinatory rules
implies top down info
regularisation errors- what type of dyslexia?
SURFACE
What kind of patients do worse with irregular words?
Semantic dementia with surface dyslexia / surface dyslexics
