Chapter 14: Parietal Lobes

Question 1

What is the primary function of the parietal lobes ?

Answer 1

• to process and integrate somatosensory and visual information
• especially as it applies to movement

Question 2

How do we study the parietal lobe?

Answer 2

• this part of the brain is more difficult to study in animals because animals have small parietal regions in comparison to humans
• ours (humans) have evolved to a much greater extent than that of rats, cats

Question 3

Who is patient HP and what where their deficits?

Answer 3

• 28 year old accountant diagnosed with a tumour in the left parietal lobe
• issues with simple subtraction, knocking over water glass, issues manipulating a rubix cube, words become flipped and backwards, difficulty distinguishing left and right

Question 4

Where does the parietal lobe sit in the brain in reference to the other lobes?

Answer 4

• the parietal lobe lies between the frontal and occipital lobes, and above temporal
• behind central fissure and above sylvian fissure

Question 5

Is the parietal lobe a singular function zone?

Answer 5

• no

- it can be divided

Question 6

Which Brodmanns areas are included in the anterior parietal area?

Answer 6

The anterior parietal areas includes brodmanns areas 3, 1, 2, ( the three along the central sulcus ) and adjacent region area 43 (circle to the right of BA2)

Question 7

Which Brodmanns areas are included in the posterior parietal cortex/ how is it divided ?

Answer 7

The posterior parietal cortex is further divided into the superior and inferior regions

• superior: brodmanns areas 5 and 7
• inferior: brodmanns areas 40 and 39

Question 8

Who is Constatine Von Economo ? (VE)

Answer 8

• He is an austrian psychiatrist, he studied the parietal area similar to Brodmanns
• he mapped 4 anterior parietal areas PA, PB, PC, PD
• he mapped 3 posterior parietal ares PE, PF, PG

Question 9

What is important about where area PG is located?

Answer 9

• may have implication in the STS pathway
• it overlaps with the occipital lobe
• area PG is more expanded in humans

Question 10

What is the Precuneus region?

Answer 10

• it is the least understood region
• primarily because of its location, but location seems to be important in sensorimotor functioning
  (located roughly where PE is but inside )

Question 11

What are Saccadic Eye Movements?

Answer 11

• rapid and abruptly changing the point of fixation

- saccadic eye movements are controlled by the parietal cortex

Question 12

What is the Lateral Intraparietal area involved in?

Answer 12

• controls saccadic eye movements

- this brain region has a high degree of overlap between the parietal and the occipital lobes

Question 13

What is the Anterior Intraparietal area responsible for?

Answer 13

• visual object-directed grasping

Question 14

What is the Parietal reach region involved in ?

Answer 14

• plays a role in visually guided reached movements

Question 15

What does Polymodal mean?

Answer 15

• polymodal cells receive input from more than one sensory modality
• the majority of the cells in the parietal lobe are polymodal

Question 16

What is Stereognosis

Answer 16

• tactile perception

Question 17

What is afferent paresis

Answer 17

• loss of kinesthetics feedback, makes finger movements clumsy

Question 18

What is Asterognosis

Answer 18

• the inability to recognize objects by touch

Question 19

How can you test for tactile perception (Asterognosis)

Answer 19

2 common tests
patients are blind folded and objects are EITHER placed on their palm OR they are told to handle shapes, than you match the original shape to one of several alternatives

Question 20

What is Simultaneous Extinction

Answer 20

• This disorder is when a patient loses the ability to detect a sensory event when it is paired with an identical one on the opposite side of the body or visual space.
• it is unnatural to experience the world one item at a time

Question 21

Damage to areas PE and PF result in ?

Answer 21

• More often results from damage to the right hemisphere, lose sight of things in the left visual field. Damage is most common in areas PE and PF.

Question 22

How can you test for Simultaneous Extinction

Answer 22

-These involve presenting two tactile stimuli simultaneously to the same or different body parts. The objective is to uncover those situations in both stimuli

Question 23

What is Numb Touch
Who reported it
Where was the damage in the brain
What are the symptoms

Answer 23

• often called blind touch or numb touch
• Jacques Pillard in 1983
• woman who appears to have the tactile analogue of blindsight.
• This woman had Damage to PE/PF in left hemisphere,
• resulting in complete anesthesia of the right side to the point that patients could be cut or burned without knowing.
• However, if you touched her right arm or hand, she could point to the area with her left hand, even though she said you didn’t touch her.
• This is the only reported case of numb touch.

Question 24

What is Somatosensory Agnosias

Answer 24

• Asomatognosia is a condition where the patient loses knowledge about their own body or condition. It is almost an unbelieveable condition until you see it.
• usually affects one side and more commonly the left side

Question 25

What is Autopagnosia

Answer 25

inabiltiy to locate and name body parts

Question 26

what is anosodiaphaoria

Answer 26

indifference to illness

Question 27

What is Balints Syndrome and what are the symtpoms

Answer 27

• in 1909 Rezso Balint described a patient whose bilateral parietal lesion was associated with peculiar visual symptoms.
• oculomotor apraxia (paralysis of gaze)
• simultagnosia
• optical ataxia

Question 28

What is oculomotor apraxia

Answer 28

• paralysis of gaze.
• Can move your eyes, but cannot fixate on specific visual stimuli. Looked ahead but eyes were directed ~35-40 degrees to the right.
• Have difficulty with info in the peripherals and must move their head to see these things. Will only perceive things in the direction of their gaze and miss everything else.

Question 29

What is Simultagnosia

Answer 29

-When attention was directed toward an object, missed other stimuli. Slightly different from simultaneous extinction.

Question 30

What is Optic Ataxia

Answer 30

• visually guided movements were impaired.
• Optic ataxia by itself can emerge from unilateral or bilateral lesions, but the combination of symptoms in Balints syndrome must have damage to both hemispheres.
• Balints is rare but optic ataxia is a common symptom of posterior parietal lesions (both unilateral and bilateral).

Question 31

What is contralateral neglect

Answer 31

• A perceptual disorder that results from RIGHT parietal lobe lesions.
• Have no visual field deficits.
• Completely neglect or ignore the left side of the body and their world.
• Generally lack accurate spatial locations and exhibit topographical disability.
• The neglect occurs in the visual, auditory and somatosensory world,

Question 32

Why do Neglect patients present obstacles to our understand of the parietal lobe connections?

Answer 32

two main theories

1. defective sensation and perceptions
2. Defective attention or orientation

Question 33

What areas does the patient need in order to demonstrate neglect

Answer 33

• intraparietal sulcus and angular gyrus

Question 34

What is TMS?

What disorder

Answer 34

• Passing a strong brief current through an insulated wire coil placed on the skull. Single-pulse TMS can induce motor evoked potentials (essentially you get brain activity). You can either activate or suppress activity.