Lec 56 Cognition Flashcards
What causes akinetic mutism?
akinetic mutism = failure to move or speak = failure of “go”
- due to medial frontal lobe dysfunction
- loss of intiaitve/agency/motivation
due to: stroke, medial frontal mass lesion, trauma, degeneration
What are two hardwired neural substrates of behavior?
language
visual processig
What is an example of incidental neural substrate of behavior?
crying
What are the 2 components of consciousness?
arousal and awareness
What are the components of cognition?
- attention
- language
- memory
- perceptual processing
- praxis
- thought content
- executive
What are the 5 neuro behavioral domains?
consciousness cognition emotion behavior motor
What determines hemispheric dominance?
language lateralization
What is signficance of handedness clinically?
can infer hemispheric dominance [language lateralization] from handedness
> 90% of pop is R hand –> >98% of those are L-dominant language
60% of those are L dominant for language
What is significance of L-handers more likely to have bilateral language representation?
recover language more quickly if one side of brain is damaged [stroke]
What does non-dominant hemisphere specialize in?
nonverbal functions
- prosody [emotion conveyed by voice]
- visual spatial analysis
- spatial attention
- analytical skills based on spatial organization
What does dominant hemisphere specialize in?
- language
- praxis [motor skill planning]
- analytical skills based on sequential processing
Whaat are the 3 networks for attention?
- alerting, orienting, executing
What are the 3 main parameters used to evaluate language dysfunction?
fluency [grammar/syntax]
ability to repeat
comprehension
What areas of brain responsible for comprehension of language? function of each
- wernicke’s area [superior temporal gyrus close to primary auditory cortex]
- —> identifies auditory stimuli as having linguistic value
- transcortical sensory area [a temporo-parietal association area]
- —-> determines what this info actually means
What areas of brain responsibel for expression of language?
broca’s area [inferior frontal gyrus]
—> mediates final output for language
transcortical motor area of frontal lobe
—> assembles components of language into syntactically correct structure
What part of brain responsible for language repetition?
arcuate fasciculous = connects Broca’s and Wernicke’s
What happens in broca’s aphasia?
= expressive aphasia
- non-fluent speech missing relational words [articles, conjunctors, “telegraphic speech”]
- preserved comprehension
- impaired repetition
What happens in wernicke’s aphasia?
- impaired comprehension
- impaired repetition
- fleuncy preserved and language syntactically correct but semantically empty
paraphrasic errors
neologisms [made up words
= receptive aphasia
What is transcortical motor aphasia?
= expressive dysphasia
impaired fluency
preserved comprehension
preserved repetition
afffected individuals can not assemble sentences
What is transcortical sensory aphasia?
preserved fluency
preserved repetition
impaired comprehension
= receptive aphasia
What is conduction aphasia?
preserved fluency
impaired repetition
preserved comprehension
What is impaired in global aphasia?
everything [fluency, repetition, comprehension] all impaired
What is function of non-dominant “wernicke” homologue? broca homologue?
wernicke = speech comprehension
its homologue = detecting prosody [emotion/intonation in language]
broca = fluency
its homolgue = imbuing prosody
What is alexia [without agraphia]? cause?
disconnection syndrome caused by PCA territory stroke
What is a disconnection syndrome?
lesion in white matter disconnects the network connections between visual cortex and language processing areas –> pt loses ability to read
What are the different steps in memory?
- attention
- registration
- working memory
- evaluation for relevance
- encoding
- storage
- retrieval
What structures mediates attention in memory?
ACC [anterior cingulate], parietal
What structures mediate registration of memory?
- primary sensory cortex
- prefrontal cortex [PFC]
What structure mediates working memory?
dorso-lateral prefrontal cortex [DLPFC]
What structures mediate evaluation of memory for relevance?
limbic
ACC
DLFPC
What structure mediates encoding of memory?
hippocampus
What structures mediate storage/consolidation/retrieval or memory?
distributed circuitry
What is anterograde amnesia?
impaired ability to form new memories
What is retrograde amnesia?
lose old memories
may or may not have temporal gradient [easier to remember newer or older or same for both]
What is echoic memory?
lasts 5 se or less = perceptual echo
important for facilitating registration
What is short term memory?
seconds to minutes
What is working memory?
complex attentional circuits, tast control, short term memory systems
What is explicit/declarative long term memory?
conscious and can be semantic [memory for facts] or episodic [memory for events]
What is implicity long term memory?
non-conscious
procedural [memory for riding bike], classic conditional [stimulus association], or emotional memory
In neglect: where does dominate parietal lobe mediate attention to? what about non-dominant? significance?
dominant = contralateral hemispace non-dominant = bilateral hemispace
–> neuroanatomy of neglect mediated by non-dominant parietal lobe
What is hemi-neglect?
pt with neglect completely unaware of half their body
- from lesion in non-dominant parietal lobe causes contralateral neglect [lesion in right lobe causes neglect on left]
What is agnosia?
intact perception but dysfunction of associational sensory processing –> impaired recognition of object
ex. visual agnosia –> inabilit to visaully recognize object even though its intact
What is anosagnosia? 2 examples?
inability to recognize one’s own deficit
- hemi-body neglect
- anton’s syndrome –> cortical blindness but unaware of deficit
What happens if you have complete unilateral loss of perception?
sensory field cut
How do you test neglect?
line bissection test
clock test
What is dyspraxia?
inability to perform previously learned motor task
What is praxis? type of info needed?
praxis = act of translating intent into act
requires:
1. conceptual = what to do
2. performance = how to do it
What is praxicon?
like a lexicon = a store of motor programs
What is path to get praxis on right side [assuming left dominant]?
left parietal sends signal to SMA and other premotor areas –> send signal to left motor cortex –> left corticospinal tract –> right praxis
What is path to get praxis on left side [assuming left dominant]?
left parietal sends signal to SMA and other premotor areas –> send signal via corpus callosum to right motor cortex –> right corticospinal tract –> left praxis
What are the 3 functional subdivisions of executive prefrontal cortex?
- medial PFC/Anterior cingulate = “go”
- orbitofrontal cortex = “No Go”
- dorsolateral and ventrolateral PFC = “How to go”
Match these function subdivisions of prefrontal cortex with their function
- medial PFC/Anterior cingulate
- dorsolateral and ventrolateral PFC
- orbitofrontal cortex
A. No Go
B. Go
C. How to Go
- medial PFC/Anterior cingulate = “go”
- orbitofrontal cortex = “No Go”
- dorsolateral and ventrolateral PFC = “How to go”
What is function of medial PFC-ACC subdivision?
“Go”
Function = motivation, initiative, agency
What happens in medial PFC-ACC subdivision dysfunction? causes?
abulic-akinetic syndrome or akinetic mutism
causes: ACA stroke, medial frontal mass lesion, trauma, degeneration [frontotemporal dementia]
What is function of orbitofrontal cortex subdivision?
“No Go”
provides brakes/inhibition
What is function of dorsolateral-ventrolateral PFC subdivision?
“How to Go”
executive function
What happens in orbitofrontal cortex subdivision dysfunction?
disinhibition, perseveration
What happens in dorsolateral ventrolateral PFC subdivision dysfunction?
problems with shifting from 1 set to another, impaired maintenance of goal, task control, impaired error monitoring
What does clock test tell you?
executive dysfunction
What 2 components make up frontal lobe?
M1 and prefrontal cortex
What components make up prefrontal cortex?
- premotor cortex
- supplementary motor area
- frontal eye fields
- brocas
- transcortical motor
- executive prefrontal cortex
