Lesions and Language Flashcards
brocas aphasia damage to what?
- inferior frontal gyrus
wernickes aphasia damage to what ?
- superior temporal gyrus
2 aims of cognitive neuroscience
- to identify processes that underlie NORMAL cognition
2. to localize these processes to particular neural structures/systems
what does the lesion method allows us to do
look at what would normally be going on in a specific brain area, localize the processes as well as how the processes are organized
infer what mental processes a brain area implements by observing what behavioural deficit a patient shows when that brain area is damaged
lesion method
understanding the mind by studying the brain - traditional approach was to use the lesion method
cognitive neuropsychology
what is the assumption in cognitive neurospychology
- localization of function/modularity
- -> each mental process is carried out by a particular part of the brain
what are the pros of single case studies (2)
- one patient can be studied in great detail
- allows the study of extremely rare conditions
what are the cons of single case studies
- the pattern observed for one individual may not be representative of ppl in general (may have atypical brain)
what are the pros of group studies
- avoids conclusions based on a single patient
2. more generalizable to the population at large
what are the cons of group studies
the group average may not reflect particular patient (half could be good and half could be bad, is that really reflective the average? )
3 ways to damage brain cells
- deprive them of oxygen and nutrients
- damage them mechanically
- subarachnoid hemorrhage
how do cells get damaged from deprivation of oxygen and nutrients
ischemia: blood flow cut off
deprivation >10 minutes = cells die
-
what is an area of dead tissue called
lesion or infarct
3 ways to damage cells mechanically
- blow to the head or penetrating object
- - direct damage - increase intracranial pressure
- – cells are squashed - surgical removal of brain tissue
- – cells are deliberately removed
what is an subarachnoid hemorrhage
- what can it lead to (3)
rupture of a cerebral artery
- can lead to ischemia
- can result in subdural hemotoma (a clot=increase pressure)
- blood block drainage of CSF from the ventircles (causes increased intracranial pressure)
a cerebral infarct is due to a ________, an excessive discharge of blood
hemorrhage
5 major causes of brain damage
- head injuries
- cerebrovascular causes
- brain tumors
- neurotoxins
- neurolgical diseases
brain injuries in which the skull is penetrated
open head injuries
a blow to the head
- acceleration and deceleration of the brain inside the skull
closed head injuries
can sometimes lead to very diffuse damage but sometimes focal
closed head injuries
3 things head injuries can cause
- direct structural damage
- damage to cerebral vasculature (subarachnoid hemorrhage, subdural hematoma)
- cerebral edema (swelling)
- -> collection of fluid around damaged tissue, increased intracranial pressure (more squashing)
2 cerebrovascular causes of damage
- cerebrovascular blockages - lead to ischemia or hemorrhage (thrombosis, embolism, arteriosclerosis)
- aneurysms- vascular dialation resulting from local defects in blood vessel elasticity
- also stroke and infarct
sudden appearance of neurological syptoms as a result of severe interruption of blood flow
stroke (can cause an infarct)
location of damage depends on ?
the artery that is blocked or damage
a mass of new tissue that persists and grows independently of its surrounding structures and has no physiological use
tumor
a tumor that arises from glial cells
and is ____and _____
gliomas
- malignant and infiltrating
a tumor from growths attached tot he meninges
meningiomas
a tumor that established by a transfer of tumor cells from elsewhere in the body
metastatic
meningiomas are _____ and _______
benign and encapsulated
metastatic tumors are ____ and ______
malignant and infiltrating
exposure to natural or manmade toxic substance - alters normal activity of nervous system disrupting or killing neurons and glia
neurotoxicity
neurotoxicity can result from exposure to ? (5)
- radiation or chemotherapy
- heavy metals (lead or mercury)
- drugs
- certain foods or additives
- industrial and or cleaning solvents
neurotoxins often result in ____ brain damage
diffuse
some neurotoxins can produce very specific damage (2)
- alcohol– mamilary bodies (karsakoffs amnesia)
2. MPTP (related to heroin)- substantia nigra (drug- induced parkinsonism)
_______ causes widespread cortical degeneration, and _______ causes degeneration of substantia nigra
alzhemiers
parkinsons
overall smaller size of brain, shrinking of gyri, widening of sulci
alzhemiers
5 issues with lesion method
- preexisting patient variability (age, ese, education, intelligence)
- variability of lesion(location size etiology), accidents of nature not controlled
- poor temporal and spatial resolution!
- compensatory strategies: patients may use alternative strategies that normally depend on damaged areas
- fibers of passage- damaged in an area not directly involved in a task
what is the wernicke lichtheim geschwind model?
- what is it built on?
- based on?
a theory / model of how langauge is implemented in the brain
- built on the early wor of broca, wernicke and lichtheim in the 1800
- based on lesion studies of aphasia
what is the pathway for spoken language perception
auditory sensory pathway –> primary auditory cortex –> wernickes area —> higher level cortex
what is the pathway for written language perception
visual sensory pathway –> primary visual cortex –> secondary visual cortex —> angular gyrus –> wernickes area –> higher level cortex
what is the pathway for spontaneous spoken langauge
higher level cortex –> wernickes areas –> arcuate fasciculus –> brocas area —> primary motor cortex
what is the pathway for repetition of speech
auditory sensory pathway –> primary auditory cortex –> wernickes area –> arcuate fasciculus –> brocas area –> primary motor cortex
lesion on arcuate fasiculus = ?
conduction aphasia
lesion on path from higher level cortical areas to brocas area = ?
transcortical motor aphasia
lesion on path from brocas area to motor cortex =?
dysarthria aphasia
lesion on path from wernickes area to higher level cortex = ?
transcortical sensory aphasia
lesion on path from primary auditory input to wernickes area = ?
pure word deafness
4 modalities used to test aphasias
spoken language perception and production and written language perception and production
aphasia are often caused by ____ typically to the ____ side on brain
stroke, left
what needs to happen for it to be a true language deficit?
must show up across multiple modalities (spoken and written)
brocas aphasia is also known as ?
expressive aphasia, motor aphasia
spontaneous speech is slow, labored and non fluent
brocas aphasia
repetition is slow laboured and non fluent
brocas aphasia
comprehension relatively spared but poor syntax/grammer comprehension
brocas aphasia
what does writing look like for brocas aphasia
shows the same errors as speech
if they switch from saying something that they arnt trying to come up with on the spot to a well known it phrase or singing it will come out quite smoothly
- what aphasia?
- why does this happen?
- brocas aphasia
- non relying on language system as much but on highly practices physical action
wernickes apashia is also called?
- receptive aphasia
- sensory aphasia
have fluent speech that is fluent, unlabored, prosodic but meaningless
wernickes aphasia
neologisms
nonsense words in wernickes
aphasia
spontaneous speech severely impaired, repetition severely impaired, writing severely impaired
global aphasia
global aphasia is associated with damage to?
brocas area and wernickes area
wernickes aphasia with intact sentence rep
transcortical sensory aphasia
brocas aphasia with intact sentence rep
transcortical motor aphasia
global aphasia with intact sentence rep
mixed transcortical aphasia
relatively intact production of speech and comprehension but severly impaired repetition
conduction aphasia
anarthria/dysarthria
impaired speech production
auditory verbal agnosia/pure word deafness
impaired speech perception
alexia/dyslexia
impaired reading
agraphia/dysgraphia
impaired writing
anomia/dysnomia
impaired naming
3 issues with the cognitive processes approach
- distributed processing
- overlapping processing
- individual differences in structure and functional anatomy
what is apraxia of speech
disorder in programming the speech musculature to produce the correct sounds words in the proper sequence with the appropriate timing
4 symptoms of apraxia
- inconsistent articulatory errors
- articulatory grasping
- disruption in prosody
- disruption in rate of speech
apraxia is not a _______ problem
perceptual. no problem perceiving or recognizing speech sounds, including their own articulatory errors
