PY2507.4 ~ {Laterization + Aphasia + Dyslexia & Dysgraphia}
aphasia
acquired disorders of language [from greek 'a' = without + 'phemio' =to speak + language deficits stem mainly from lesios to temporal and frontal lobes + its a cognitive disorder
what can language impairments affect
in diff combinations + speech comprehension & comprehension + reading & writing + diff parts of speech [content vs function words] + diff semantic categories + in reading regular vs irregular words
Wernicke's Model
he put forward the first neuro-anatomical model of language + predicted existence of third type of apahasia [where connection between motor + sensory areas was disrupted but bith areas intact
conduction aphasia
later confirmed by empirical studies + results from damage to bundle of nerve fibres that connects Broca's area & Wernicke's area [arcuate fasciculus]
types of aphasia's according to Wernicke's model
motor (Broca's) + sensory (Werncike's) + conduction
Motor (Broca’s) aphasia
damage to cortical center [where motor images of words are stored] + deficit of language production + slow effortful speech + mainly limited to content words - telegraphic quality
Sensory (Wernicke’s) aphasia
damage to cortical center [where auditory images of words are stored] + poor comprehension + fluent speech, but with phonological & verbal paraphasias
conduction aphasia symptoms
spared [good] comprehension + speech similar to Wernicke aphasia [fluent] + very impaired repetition + slef-correction attempts [which show patient is aware of their errors] + paraphasias
paraphasia
words that are incorrect but somewhat resemble intended word, this involved making phonetic errors [such as 'park' instead of 'bark' + saying 'dog' instead of 'cat'
telegraphic quality
style of speech or writing where many function words [is, the, a] are omitted leaving only key content words [nouns, verbs, adj]
content vs function words
c - carry main meaning or semantic load of sentence, refer to objects, actions or concepts [nouns, verbs, adj, adv]
f - serve a grammatical purpose, help structure sentences don't carry sig meaning on their own + connect words to provide context, tese or structure
`ludwig Lichtheim - further extensions
extended Wernicke's predictions + produced Lichtheim's house diagram [1895] - aimed to explain how damage to diff brain areas could result in distinct aphasia types
diff between Wernicke's & Broca's aphasia
w - impaired comprehension, fluent but nonsensical speech
b - non-fluent speech, but good comprehension
diagram markers
in Lichteim's house diagram - predicted apahasia types by making diagrams & assesing the consequences of damage to either brain centres + connections between them
Lichtheim’s House Diagram
theoretical framework organized to represent a model of how language processing worked = concept center to the right
concepts
predictions of aphasia types using diagram
damage to Wernicke's area [auditory center] = Wernicke's aphasia + damage to Broca's area [motor center] = Broca's aphasia + d to arcuate fasciculus [connection] conduction aphasia + d to concept center = more severe aphasia
example of Ldiagram
[Concept Center]
/\
/ \
/ \
[Auditory Center] [Motor Center]
| |
\_______________/
|
[Arcuate Fasciculus (Connection)]
demise of the Lichtheim's model
problems with anatomical aspects of model, lack of correspondence between even pure syndromes + hypothesized locus of lesion + prob with cog aspect of model, variety of symptoms could still not be captured by few discrete syndromes
globalist approach
by Pierre Marie [french neurologist] + Henry Head [english neurologist] = believed there is only 1 form of aphasia [wernicke's] + aphasic deficits involved impairment of thinking & lowered intelligence + thoguh group result case studies were more reliable than single
globalist approach demise
low correlation between severity of aphasia and performance IQ + potential prob with avging results in studies involving groups of patients who hav diff brain lesions or cog impairments
modern neuropsych aims
to understand cognition + to understand relationships between cog & the brain + to identify the specific cog or language impairments suffered by an individual
cog neuropsych approach [cog model]
put these first = provides framework to interpret diff impairments seen in patients + no 2 patients are alike + all symptoms shown by patient can be interpretable
what does Broca's aphasia fractionate into
word production & sentence production & spelling impairments [last 2 = agrammatism]
what does Wernicke's aphasia fractionate into
word comprehension & word production & sentence processing & reading impairments
what does Conduction aphasia fractionate into
phonological encoding & phonological STM impairments
traditional vs cog neuropsych
tn = medical framework + group studies + behaviourism
cn = computational framework + single case studies + cognitivism
activation studies - Price, C. (2012)
consensus that diff brain areas are involved in processing diff types of info during language tasks - these are activated at diff times
Diffusion tension imaging studies
allowed us to identify 2 pathways involved in language processing = dorsal + ventral pathway
dorsal pathway
phonology = articulation, pathway is from temporal lobe to pre-motor cortex + broca's [helps translate auditory info into motor commands for producing speech]
ventral pathway
phonolgy = semantics,pathway is from TL to IFL, involved in processing meaning of words + intergrating them into broader contexts