EEG- Dr. Connolly Lecture Flashcards
Children diagnosed as non-verbal autistic are also associated with having…
Severe intellectual disabilities
(10-15% aren’t actually at the intellectual
disadvantage that the diagnosis entails)
Locked in condition
your can functionally think and understand but you cannot move or demonstrate it (kind of like being awake but under anaesthesia)
fMRI measures..
changes in blood flow in different brain areas
very poor temporal resolution
MEG
Looks at magnetic fluxes of the brain
much better at telling where a signal originated than EEG
EEG
less robust in terms of where signals come from
the ideal is to combine MEG and EEG
ERP
(event related potential)
average stimulus of trials.. a signal to noise ratio (the brain insists on doing many things at once)
-the stimulus must be repeated many times in order to determine where it is amongst all the “noise”
N400
semantic processing in the visual/auditory modality
“the winter was harsh this allowance”
Large N400 at unexpected semantic stimulus
PMN
response to processing speech at a phonological level
What kind of PMN
“the winter was harsh this allowance”
Large PMN at [a]llowance
when the [a] phoneme appears PMN occurs because you’re expecting to hear a “y” sound for “year”
What kind of PMN / N400
“The pigs wallowed in the pen”
no N400 ("pen" works in the sentence)
PMN appears (expecting to hear "m" for mud)What kind of PMN / N400
“The gambler had a streak of bad luggage”
Large N400- expecting “luck”
No PMN - “L” phoneme works for luck and luggage
PMN reflects a pre-lexical stage of processing (T/F)
TRUE
present in word/nonword matches in rhyming tasks
PMN
response to processing speech at a phonological level
begins 200 ms after onset
PMN reflects a pre-lexical stage of processing (T/F)
TRUE
present in word/nonword matches in rhyming tasks
Test: Phoneme deletion paradigm
done to avoid N400
CLAP without the [k] Correct deletion: LAP Incorrect: CAP Initial consonant cluster: AP Irrelevant (control): MILK Able to see the difference between correct and incorrect deletion responses in the brain
Test: Homophones reading (N400)
Congruent: “A dove is a sign of peace”
Foil: “we baked a cake and ate a peace”
Incongruent: “the car ran out of bawl”
Congruent and Foil had little to no N400
Vegetative state (VS)
ABI (acquired brain injury) with no evidence of awareness of self or environment / inability to interact with others
no evidence of comprehension of language
New method to test vegetative state vs. Locked-in condition
ERP assessment of cognitive function
looking for N400 and PMN responses in patients
What about autism?
25% of kids diagnosed with autism are considered non-verbal
if they know 5 functional words or less= nonverbal
there must be something wrong with relying on behaviour based tests
Example of new method test on autism
GIRL:
- substantial N400 with sentences used on adults
- also could recognize her name
- must mean she’s not truly non-verbal because she can comprehend language well
BOY
- small hint of N400 but not strong in adult sentences
- Did not understand his name
- he cannot comprehend language
Individual variation
Example of new method test on VS patients
Male stabbed in head
- 3-4 weeks after adult he showed N400 (clear semantic understanding)
- 2 months later- became more robust
- determined not VS and got rehab therapy
Neuropsychological test paired with ERP tests …
provide “value-added” methodology for non-verbal or non-communicative individuals
-provides better understanding of their condition
