Parietal Lobe Syndrome

Question 1

In very broad terms, what happens on the left side of the brain? (2 things)

Answer 1

Language, praxis

Question 2

In very broad terms, what happens on the righ side of the brain? (3 things)

Answer 2

Prosody, spatial representation, attention…

Question 3

What’s the anterior-posterior dichotomy of the brain, roughly?

Answer 3

Anterior for output, posterior for perception.

Question 4

What’s the dorsal/ventral dichotomy of the brain, roughly?

Answer 4

Dorsal: “Where?”
Ventral: “What?”

Question 5

Where is the hetero-modal association cortex? What does it do?

Answer 5

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.

Question 6

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?

Answer 6

Visual receptive field will expand to include the tool (we consider it part of our hand, which is cool)

Question 7

What does knowledge of affordances mean? Part of brain involved?

Answer 7

Knowing where to grasp a tool without having used it before. Left inferior parietal lobule.

Question 8

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?

Answer 8

Left inferior parietal lobe.

Question 9

What part of your brain allows you to actually swing your arm to use a hammer effectively?

Answer 9

Pre-motor cortices.

Question 10

Most cases of apraxia, even when the left hand is the clumsy, are localized where?

Answer 10

In the left hemisphere.

Question 11

What is the “most discussed” kind of apraxia?

How do you test for apraxia?

Answer 11

Ideomotor apraxia. Have patient pantomine actions to imitation and verbal command. Have them ID your pantomimes.

Question 12

Common causes of ideomotor apraxia? (name 3)

Answer 12

Cortico-basilar ganglionic degeneration (CBGD), Alzheimer’s disease, focal error

Question 13

What’s particular characteristic of ideomotor apraxia in Alzheimer’s?

Answer 13

“limb-as-tool” apraxia - trying to hammer in the nail with their fist

Question 14

What is lesioned in “contralateral” apraxia? Will the patient be able to discriminate between poorly and well-performed movements done by someone else?

Answer 14

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.

Question 15

What kind of lesion will cause bilateral ideomotor apraxia? Will the patient be able to judge / identify movements of others?

Answer 15

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.

Question 16

What two number skills live in the right parietal lobe?

Answer 16

Subitizing (quickly counting numbers < 5)

Estimating quantities

Question 17

What is subitizing? What visual process might it be related to?

Answer 17

Rapid counting of small quantities < 5. Related to target tracking… keeping track of 4 moving sheep?

Question 18

What two number skills live in the left parietal lobe?

Answer 18

Counting (linked to language), arithmetic

Question 19

What are the 4 signs of Gerstmann’s syndromes? Localization? one of these “always appears on the boards” things

Answer 19

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

Question 20

Where does “visual attention” i.e. the opposite of “neglect” live?

Answer 20

In the right parietal lobe.

Question 21

Why doesn’t Barley eat the food on the left side of her bowl?

Answer 21

Left-sided neglect from stroke on right (caused transient left-sides weakness, but the neglect persisted)

Question 22

What specific vascular lesion can cause left-neglect?

Answer 22

Right MCA, particularly right posterior MCA stroke.

Question 23

Can right-sided neglect happen?

Answer 23

Yes, but it tends to be transient. We don’t know why.

Question 24

What does anosognosia mean?

Answer 24

Unilateral lack awareness of one side of the body. (E.g. only shaves one side of beard)

Question 25

What is somatophrenia?

Answer 25

Patient believes limb doesn’t belong to him/her.

Question 26

What is the difference between hemi-space and hemi-object neglect?

Answer 26

Hemi-space: Only see right side of scene.

Hemi-object: Only see right side of objects within the scene.

Question 27

What hypothesis is supported by seeing lesions in different regions for patients with hemi-space vs. hemi-object neglect?

Answer 27

There are different anatomical sites for different frames of reference.

Question 28

Which is more dorsal: hemi-space or hemi-object neglect?

Answer 28

Hemi-space neglect is more dorsal, hemi-object neglect is more ventral.
This is consistent with “Dorsal = Where? ; Ventral = What?”

Question 29

Is “sidedness” at least partially in respect to the orientation of the body?

Answer 29

Yes.

Question 30

What affect does bringing neglected arm across to right side of the body have?

Answer 30

Patient will usually report increased strength / perception of it.

Question 31

Describe the concept of extinction in neglect. What makes for a weak/strong stimulus?

Answer 31

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.

Question 32

Why do we think info on left side might be still getting to the brain?

Answer 32

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…

Question 33

What are 3 signs of Balint’s syndrome? Localization?

Answer 33

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.

Question 34

3 causes of Balint’s syndrome?

Answer 34

Tau-opathies, prion disease, PML/RPLE (weird brain inflammation)