Ch. 14 Flashcards
What is the function of the parietal cortex?
To process & integrate somatosensory & visual information
What is the function of area PE?
Basically somatosensory -> plays a role in guiding movement as it provides information about limb position
What is the function of area PF?
Mostly somatosensory
What is the function of area PG?
Receives more complex connections; visual, somesthetic, proprioceptive, etc; part of the dorsal stream, helps to guide spatially guided behavior
What are the 3 functional pathways of the dorsal stream?
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)
What are the functions of the anterior & posterior parietal zones?
Anterior -> somatosensory (somatic sensation & perception); Posterior -> spatial (integrates sensory input from somatic & visual regions to control movement)
What can be thought of as the “organ” of the posterior parietal cortex (PPC)?
The hand
What is sensorimotor transformation?
Neural calculations that integrate movements of different body parts w/ sensory feedback of what movements are actually being made & plans to make those movements
Most neurons in the PPR are active during ________ and ________.
Somatosensory input & movement
What are three important characteristics of PPR neuronal responses?
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
What is “route knowledge”?
A way to describe a cognitive spatial map that allows us to travel through our environments
What is one suggestion of where route knowledge is represented in the brain?
In the medial parietal region (MPR) of the parieto-medial-temporal pathway (dorsal stream); MPR cells respond to specific movements ONLY at specific locations
What are three parietal-lobe symptoms that don’t fit into a simple view of a visuomotor control center?
Difficulties w/ arithmetic, language, and movement sequences
Damage to the postcentral gyrus is typically associated w/ what changes?
Changes in somatosensory thresholds -> deficits in stereognosis (tactile perception)
What is afferent paresis?
Loss of kinesthetic feedback -> causes clumsy finger movements due to loss of feedback about exact finger movements
What is astereognosis?
Inability to recognize the nature of an object by touch
What is simultaneous extinction?
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
What is numb touch?
The tactical version of blindsight -> complete anesthesia but ability to accurately identify certain somatosensory experiences
What is asomatognosia?
The loss of knowledge/sense of one’s own body & bodily condition
What are the four kinds of asomatognosia?
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)
What is finger agnosia?
The inability to point to fingers of either hand or show them when prompted
What are the two stages of recovery from contralateral neglect?
1) Allesthesia -> person begins to respond to stimuli on neglected side; 2) Simultaneous extinction
What are the two theories behind contralateral neglect, and which is favored?
1) Defective sensation/perception (favored; states that lesions to parietal lobes disturb the integration of sensation & perception); 2) Defective attention/orientation
What is a term to describe the integration of sensory & perceptive information?
Morphosynthesis
What are the 4 conditions that make up Gertsmann syndrome?
Finger agnosia, Agraphia, Acalculia, Left-right confusion
Posner proposed that one function of the parietal cortex is to allow attention shift from one stimulus to another, which he called ______.
Disengagement
What clinical test is administered to test somatosensory threshold? Describe it.
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
What clinical test is administered to test tactile form recognition?
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
What clinical test is administered to test contralateral neglect?
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
What clinical test is administered to test visual perception?
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
What clinical test is administered to test spatial relations?
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
What clinical test is administered to test language?
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
What clinical test is administered to test apraxia?
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
What are the four proposed forms of apraxia?
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
