Chapter 14: Parietal Lobes Flashcards
What is the primary function of the parietal lobes ?
- to process and integrate somatosensory and visual information
- especially as it applies to movement
How do we study the parietal lobe?
- 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
Who is patient HP and what where their deficits?
- 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
Where does the parietal lobe sit in the brain in reference to the other lobes?
- the parietal lobe lies between the frontal and occipital lobes, and above temporal
- behind central fissure and above sylvian fissure
Is the parietal lobe a singular function zone?
- no
- it can be divided
Which Brodmanns areas are included in the anterior parietal area?
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)
Which Brodmanns areas are included in the posterior parietal cortex/ how is it divided ?
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
Who is Constatine Von Economo ? (VE)
- 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
What is important about where area PG is located?
- may have implication in the STS pathway
- it overlaps with the occipital lobe
- area PG is more expanded in humans
What is the Precuneus region?
- 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 )
What are Saccadic Eye Movements?
- rapid and abruptly changing the point of fixation
- saccadic eye movements are controlled by the parietal cortex
What is the Lateral Intraparietal area involved in?
- controls saccadic eye movements
- this brain region has a high degree of overlap between the parietal and the occipital lobes
What is the Anterior Intraparietal area responsible for?
- visual object-directed grasping
What is the Parietal reach region involved in ?
- plays a role in visually guided reached movements
What does Polymodal mean?
- polymodal cells receive input from more than one sensory modality
- the majority of the cells in the parietal lobe are polymodal
What is Stereognosis
- tactile perception
What is afferent paresis
- loss of kinesthetics feedback, makes finger movements clumsy
What is Asterognosis
- the inability to recognize objects by touch
How can you test for tactile perception (Asterognosis)
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
What is Simultaneous Extinction
- 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
Damage to areas PE and PF result in ?
- 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.
How can you test for Simultaneous Extinction
-These involve presenting two tactile stimuli simultaneously to the same or different body parts. The objective is to uncover those situations in both stimuli
What is Numb Touch
Who reported it
Where was the damage in the brain
What are the symptoms
- 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.
What is Somatosensory Agnosias
- 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
