Chapter 14 - Parietal Lobe Flashcards
1
Q
What’s the general function of the parietal lobes?
A
- Process and integrate somatosensory and visual information, especially as it pertains to movement control
2
Q
What purpose does the intraparietal sulcus have?
A
- Divides the inferior and superior parietal lobes
3
Q
What components make up the inferior parietal lobe?
A
- Supramarginal gyrus (crescent-shaped)
- Angular gyrus (posterior to supramarginal gyrus)
4
Q
What’s another term for the postcentral gyrus?
A
- S1 (primary somatosensory area)
5
Q
Which Brodmann’s areas correspond to the superior and inferior parietal lobes?
A
- Superior - 5 and 7
- Inferior - 40, and 39
6
Q
Which Brodmann’s areas correspond to the anterior zone of the parietal lobes?
A
- S1 (1-3)
- 43
7
Q
What types of sense is closely associated with the angular gyrus/area PG BA 39)?
A
- It’s largely visual and contains polymodal regions
- Larger in the right hemisphere.
8
Q
What type of inputs does area PG receive?
A
- Visual, somatosensory, oculomotor (eye movements), cingulate (cognition, emotion), auditory
9
Q
What roles does area PG have?
A
- Role in intermodal mixing
- Role in spatially-guided behaviour with respect to both visual and tactile information
10
Q
What general functions does the dorsolateral prefrontal cortex have (DLPFC)?
A
- Internally-motivated behaviour
- Working memory
- Planning
11
Q
Which other brain regions are areas PG/PF highly connected to?
A
- The DLPFC and the OFC
12
Q
T/F: Posterior parietal areas and dlPFC project to very different areas as a form of parallel processing.
A
- FALSE
- They both project to very similar areas including the paralimbic cortex, hippocampus, and various subcortical regions
13
Q
Parieto-premotor stream?
A
- Apart of the dorsal stream anatomy
- The principle unconscious “how” pathway
- Affects motor output most directly
14
Q
Parieto-prefrontal?
A
- Apart of dorsal stream anatomy
- May be related to working memory for visuospatial objects
15
Q
Parieto-medial-temporal?
A
- Apart of dorsal stream anatomy
- Role in spatial recognition and spatial navigation
- More perceptual/conscious
- Projects to the hippocampus and the parahippocampal regions
16
Q
Role of anterior zones in parietal lobe function?
A
- Processes somatic sensations and perceptions
17
Q
Role of posterior zones in parietal lobe function?
A
- Integrates somatic and visual input to control movement
- Involved in mental imagery (ex. object rotation, arithmetic, reading etc.)
18
Q
What’s acalculia?
A
- Inability to perform mathematical computations
19
Q
What’s the name for Brodmann’s area 40?
A
- Supramarginal gyrus
20
Q
What would damage to S1 cause?
A
- Affects thresholds for detecting touch
- Can create high sensory thresholds (i.e., less sensitive to stimuli)
21
Q
WHat’s afferent paresis?
A
- Difficulty executing smooth, coordinated movements due to loss of afferent (somatosensory) feedback from the muscles. Don’t have info on what you’re doing
- Often caused by damage to S1
22
Q
What is astereognosis?
A
- A somatoperceptual disorders
- The inability to recognize an object by touch
- Have normal thresholds, but patient is unable to recognize objects when blindfolded
- “A loss of body knowledge”
23
Q
What can cause astereognosis?
A
- Small lesions to S1
24
Q
What’s simultaneous extinction?
A
- A somatoperceptual disorder- The failure to perceive a sensory stimulus only if that stimulus is presented simultaneously with a second stimulus
25
What can cause simultaneous extinction?
- Damage to secondary somatic cortex (areas PE and PF) in RIGHT hemisphere
- ALWAYS RIGHT HEMISPHERE
26
How would you test for extinction in a stroke patient?
- When holding up two objects, patient would have to focus on one object at a time, using their left visual field to identify the object.
27
What's numb touch?
- A type of somatoperceptual disorder
- It's the tactile analogue of blindsight
- Loss of tactile perception, but are able to locate objects through touch (better than chance selections)
- Very rare
28
Asomatognosia?
- Loss of knowledge or sense of one's own body and bodily condition
- Most commonly due to right hemisphere lesions
29
What are the different types of asomatognosias?
- Anosognosia - unawareness or denial of illness
- Anosodiaphoria - indifference to illness (able to recognize it, but doesn't care)
- Autopagnosia - inability to localize and name body parts, caused by left hemisphere damage
- Asymbolia for pain - absence of typical reactions to pain, such as reflexive withdrawal from a painful stimulus. Get easily injured. Associated with insular lesions
30
Balint syndrome?
- A host of symptoms of posterior parietal damage
- Usually associated with large bilateral lesions, resulting in deficits in visual attention, as well as motor function
31
What three major symptoms make up Balint syndrome?
- Oculomotor apraxia
- Optic ataxia (no visually-guided reaching)
- Simultagnosia (can't perceive more than one object at a time)
32
What's oculomotor apraxia?
- Paralysis of eye fixation with inability to look voluntarily into the peripheral visual field
33
What's contralateral neglect?
- Another symptom of posterior parietal damage
- Neglect of the body or space contralateral to a (usually) right lesion (i.e., ignore the left side of their visual field
- It's a deficit of attention, nothing wrong with visual fields
34
When asked to copy a clock drawing, the patient only fills in the right side of the drawing. What might we diagnose this patient with?
- Contralateral neglect
35
What are the stages of contralateral neglect recovery?
- Stage 1: Allesthesia
- Stage 2: Simultaneous extinction
36
Allesthesia?
- Responds to stimuli on the neglected side as if they were present on the unlesioned side
- Ex. poked on left arm , they may mistake this for being poked on the right arm
37
What brain area is the locus of contralateral neglect?
- Damage to both intraparietal sulcus (divides vs. inferior parietal lobe) and right angular gyrus are necessary
38
What's one theory for why contralateral neglect occurs?
- Left hemisphere orients attention towards right visual space
- Right hemisphere orients attention to both visual hemifields
- Loss of left parietal function could be compensated for by right hemisphere
39
What's Gerstmann syndrome and its symptoms?
- Caused by damage to left parietal lobe
- Symptoms include finger agnosia (can't recognize fingers), agraphia (can't write) , acalculia, right-left confusion
40
What may disturbed language function indicate?
- May be a symptom of left parietal damage
41
What's apraxia and impaired recall?
- Both may indicate damage to left parietal lobe
- Apraxia - loss of skilled movement
- Impaired recall - Unable to recall a list of numbers properly whether presented orally or visually
42
T/F: Apraxia can be caused by intellectual deterioration.
- FALSE
- Apraxia is not caused by weakness, paralysis, intellectual deterioration or poor comprehension
43
Ideomotor apraxia?
- Inability to use and understand non-verbal communication such as gestures or to copy movement sequences
- Associated with left posterior parietal lesions (right parietal performs normally)
44
How can you test for ideomotor apraxia?
- Kimura box tests (patient must move through movement series)
- Serial arm-movement copying test
- Serial facial-movement copying test
45
Constructional apraxia?
- Visuomotor disorder - spatial organization is disturbed
- Posterior parietal damage to either hemisphere
- Ex. cannot assemble a puzzle, build a tree house, draw a picture
46
Why does damage to the parietal often result in apraxia?
- There's a disruption of the parietofrontal connections that control movement
- Posterior parietal cortex receives tactile, visual, and proprioceptive afferent signals and is highly connected to frontal cortex, which commands our movements
