Ch. 14

Question 1

What is the function of the parietal cortex?

Answer 1

To process & integrate somatosensory & visual information

Question 2

What is the function of area PE?

Answer 2

Basically somatosensory -> plays a role in guiding movement as it provides information about limb position

Question 3

What is the function of area PF?

Answer 3

Mostly somatosensory

Question 4

What is the function of area PG?

Answer 4

Receives more complex connections; visual, somesthetic, proprioceptive, etc; part of the dorsal stream, helps to guide spatially guided behavior

Question 5

What are the 3 functional pathways of the dorsal stream?

Answer 5

Parieto-premotor -> proposed “how” pathway; Parieto-prefrontal -> proposed visuospatial functions related to working memory for objects; Parieto-medial-temporal -> proposed to have role in spatial recognition & navigation (flows to hippocampus & parahippocampal regions)

Question 6

What are the functions of the anterior & posterior parietal zones?

Answer 6

Anterior -> somatosensory (somatic sensation & perception); Posterior -> spatial (integrates sensory input from somatic & visual regions to control movement)

Question 7

What can be thought of as the “organ” of the posterior parietal cortex (PPC)?

Answer 7

The hand

Question 8

What is sensorimotor transformation?

Answer 8

Neural calculations that integrate movements of different body parts w/ sensory feedback of what movements are actually being made & plans to make those movements

Question 9

Most neurons in the PPR are active during ________ and ________.

Answer 9

Somatosensory input & movement

Question 10

What are three important characteristics of PPR neuronal responses?

Answer 10

1) These neurons receive combinations of sensory, motivational, and related motor inputs; 2) Neuronal discharge is enhanced when the subject attends to a target/moves towards it; 3) Area PPR only codes the desired goal of the movement, not the details of how the movement gets us there

Question 11

What is “route knowledge”?

Answer 11

A way to describe a cognitive spatial map that allows us to travel through our environments

Question 12

What is one suggestion of where route knowledge is represented in the brain?

Answer 12

In the medial parietal region (MPR) of the parieto-medial-temporal pathway (dorsal stream); MPR cells respond to specific movements ONLY at specific locations

Question 13

What are three parietal-lobe symptoms that don’t fit into a simple view of a visuomotor control center?

Answer 13

Difficulties w/ arithmetic, language, and movement sequences

Question 14

Damage to the postcentral gyrus is typically associated w/ what changes?

Answer 14

Changes in somatosensory thresholds -> deficits in stereognosis (tactile perception)

Question 15

What is afferent paresis?

Answer 15

Loss of kinesthetic feedback -> causes clumsy finger movements due to loss of feedback about exact finger movements

Question 16

What is astereognosis?

Answer 16

Inability to recognize the nature of an object by touch

Question 17

What is simultaneous extinction?

Answer 17

The inability to detect a sensory event with paired w/ an identical one (or two versions of the same kind of object, ex. two different spoons) on the opposite side of the body/visual space

Question 18

What is numb touch?

Answer 18

The tactical version of blindsight -> complete anesthesia but ability to accurately identify certain somatosensory experiences

Question 19

What is asomatognosia?

Answer 19

The loss of knowledge/sense of one’s own body & bodily condition

Question 20

What are the four kinds of asomatognosia?

Answer 20

Anosognosia (unawareness/denial of illness), Anosodiaphoria (indifference to illness), Autopagnosia (inability to localize/name body parts), Asymbolia for pain (absence of typical reactions to pain)

Question 21

What is finger agnosia?

Answer 21

The inability to point to fingers of either hand or show them when prompted

Question 22

What are the two stages of recovery from contralateral neglect?

Answer 22

1) Allesthesia -> person begins to respond to stimuli on neglected side; 2) Simultaneous extinction

Question 23

What are the two theories behind contralateral neglect, and which is favored?

Answer 23

1) Defective sensation/perception (favored; states that lesions to parietal lobes disturb the integration of sensation & perception); 2) Defective attention/orientation

Question 24

What is a term to describe the integration of sensory & perceptive information?

Answer 24

Morphosynthesis

Question 25

What are the 4 conditions that make up Gertsmann syndrome?

Answer 25

Finger agnosia, Agraphia, Acalculia, Left-right confusion

Question 26

Posner proposed that one function of the parietal cortex is to allow attention shift from one stimulus to another, which he called ______.

Answer 26

Disengagement

Question 27

What clinical test is administered to test somatosensory threshold? Describe it.

Answer 27

Two-point discrimination -> blindfold subject, ask to report whether they felt one or two points touch their skin; gradually reduce space between the points until subject perceives only one point

Question 28

What clinical test is administered to test tactile form recognition?

Answer 28

Seguin-Goddard form board (tactile patterns); Blindfolded subject manipulates 10 different blocks on a board; blocks & board are then removed, patient must draw board from memory

Question 29

What clinical test is administered to test contralateral neglect?

Answer 29

Line bisection -> Subject asked to mark middle of each set of different lines spread out randomly on a sheet of paper; those w/ contralateral neglect fail to mark the lines on the left side of the page

Question 30

What clinical test is administered to test visual perception?

Answer 30

Mooney closure & Gollin incomplete-figures -> Each test presents a series of incomplete representations of faces/objects; subject must combine elements to form a gestalt and identify the picture

Question 31

What clinical test is administered to test spatial relations?

Answer 31

Right-left differentiation -> series of drawing of body parts are presented in different orientations; subject is asked whether each drawing is of a left or right body part; verbal variant of test where subjects read instructions aloud before following them

Question 32

What clinical test is administered to test language?

Answer 32

Token test -> 20 tokens of different shapes & colors are presented to subject; test begins w/ simple identification tasks & become more difficult (ex. touch the white square); can also test reading comprehension by asking subject to read instructions themselves before following them

Question 33

What clinical test is administered to test apraxia?

Answer 33

No standardized test, one option is Kimura box test -> subject must make consecutive movements with their hands/fingers (ex. first push button w/ index finger, then pull handle w/ 4 fingers, etc.) -> Patients w/ apraxia struggle to perform the sequence despite many accurately performing each action individually

Question 34

What are the four proposed forms of apraxia?

Answer 34

Ideational apraxia -> difficulty conceiving overall goal of the movement; Ideomotor apraxia -> difficulty forming subgoals necessary to achieve main goal; Motor apraxia -> difficulty executing the actual movements necessary; Constructional apraxia -> difficulty making a series of movements to assemble components together & form an object