Parietal Lobe Syndrome Flashcards
In very broad terms, what happens on the left side of the brain? (2 things)
Language, praxis
In very broad terms, what happens on the righ side of the brain? (3 things)
Prosody, spatial representation, attention…
What’s the anterior-posterior dichotomy of the brain, roughly?
Anterior for output, posterior for perception.
What’s the dorsal/ventral dichotomy of the brain, roughly?
Dorsal: “Where?”
Ventral: “What?”
Where is the hetero-modal association cortex? What does it do?
Just posterior to the primary somatosensory cortex in the parietal lobe. “Integrated body radar’ -where things are which places in the body, where things are touching you.
So shining a laser on a monkey’s hand will light up some neurons. How does those neurons’ visual receptive field change after tool use?
Visual receptive field will expand to include the tool (we consider it part of our hand, which is cool)
What does knowledge of affordances mean? Part of brain involved?
Knowing where to grasp a tool without having used it before. Left inferior parietal lobule.
What part of your brain do you need to tell you that a can of fruit cocktail will make a better hammer than a banana?
Left inferior parietal lobe.
What part of your brain allows you to actually swing your arm to use a hammer effectively?
Pre-motor cortices.
Most cases of apraxia, even when the left hand is the clumsy, are localized where?
In the left hemisphere.
What is the “most discussed” kind of apraxia?
How do you test for apraxia?
Ideomotor apraxia. Have patient pantomine actions to imitation and verbal command. Have them ID your pantomimes.
Common causes of ideomotor apraxia? (name 3)
Cortico-basilar ganglionic degeneration (CBGD), Alzheimer’s disease, focal error
What’s particular characteristic of ideomotor apraxia in Alzheimer’s?
“limb-as-tool” apraxia - trying to hammer in the nail with their fist
What is lesioned in “contralateral” apraxia? Will the patient be able to discriminate between poorly and well-performed movements done by someone else?
Unilateral apraxia caused by a lesion to the motor cortex (which is contralateral to the limb affected).
Yes, they’ll be able to judge the quality of others’ movements.
What kind of lesion will cause bilateral ideomotor apraxia? Will the patient be able to judge / identify movements of others?
Parietal lobe. Won’t be able to judge or identify movements of others. (won’t be able to tell you that you’re making a sawing motion.
What two number skills live in the right parietal lobe?
Subitizing (quickly counting numbers < 5)
Estimating quantities
What is subitizing? What visual process might it be related to?
Rapid counting of small quantities < 5. Related to target tracking… keeping track of 4 moving sheep?
What two number skills live in the left parietal lobe?
Counting (linked to language), arithmetic
What are the 4 signs of Gerstmann’s syndromes? Localization? one of these “always appears on the boards” things
Agraphia, acalculia, finger agnosia (not knowing finger names), Right/left confusion.
Lesion to angular gyrus of left parietal lobe.
-also called a general “body schema disturbance” (autopagnosia)… but that’s not what you’ll be pimped on
Where does “visual attention” i.e. the opposite of “neglect” live?
In the right parietal lobe.
Why doesn’t Barley eat the food on the left side of her bowl?
Left-sided neglect from stroke on right (caused transient left-sides weakness, but the neglect persisted)
What specific vascular lesion can cause left-neglect?
Right MCA, particularly right posterior MCA stroke.
Can right-sided neglect happen?
Yes, but it tends to be transient. We don’t know why.
What does anosognosia mean?
Unilateral lack awareness of one side of the body. (E.g. only shaves one side of beard)
What is somatophrenia?
Patient believes limb doesn’t belong to him/her.
What is the difference between hemi-space and hemi-object neglect?
Hemi-space: Only see right side of scene.
Hemi-object: Only see right side of objects within the scene.
What hypothesis is supported by seeing lesions in different regions for patients with hemi-space vs. hemi-object neglect?
There are different anatomical sites for different frames of reference.
Which is more dorsal: hemi-space or hemi-object neglect?
Hemi-space neglect is more dorsal, hemi-object neglect is more ventral.
This is consistent with “Dorsal = Where? ; Ventral = What?”
Is “sidedness” at least partially in respect to the orientation of the body?
Yes.
What affect does bringing neglected arm across to right side of the body have?
Patient will usually report increased strength / perception of it.
Describe the concept of extinction in neglect. What makes for a weak/strong stimulus?
When receiving stimuli from both left and right, the stimulation on the left won’t be perceived, particularly if it’s weak. A weak stimulus would be an identical stimulus on the left (such as holding up a fork on each side). A strong stimulus on the left, such as a different object, might be less subject to extinction.
Why do we think info on left side might be still getting to the brain?
Patients report not wanting to live in the house with flames on the left (though they can’t point to why)… Associations with words can happen…
What are 3 signs of Balint’s syndrome? Localization?
Optic ataxia (can’t reach for visual targets - not cerebellar)
Ocular apraxia (can’t direct gaze)
Simultanagnosia (inability to see more than one thing at a time)
Can be caused by bilateral parietal lesions.
3 causes of Balint’s syndrome?
Tau-opathies, prion disease, PML/RPLE (weird brain inflammation)
