Integrate information from
vision with somatosensory
information for movement
A theory of parietal
lobe function
Use of spatial information
Object recognition
Viewer centered object identification
Posterior parietal cortex
Guidance of movement
Sensitive to eye movements
Posterior parietal cortex
Cognitive spatial map
Route knowledge,
unconscious knowledge of
how to reach a destination
Three symptoms do not
fit with the visuomotor
view of the parietal lobe
Difficulties with arithmetic
Acalculia
Might result from the
spatial properties of
addition and subtraction
Two digit number
occupy different spaces
"Borrowing" during
subtraction
Difficulties with certain
aspects of language
Words have spatial
organization
Tap vs. pat
Difficulties with
movement sequences
Individual elements of the
movement have a spatial
organization
Somatosensory
symptoms of
parietal lobe lesions
Lesions to the
post central gyrus
Abnormally high
sensory thresholds
Impaired position sense
Deficits in stereogenesis,
also tactile perception
Somatoperceptual
disorders
Astereognosis
Inability to recognize
an object by touch
Simultaneous extinction
Two stimuli are applied
simultaneously to opposite
sides of the body
A failure to report a
stimulus on one side is
referred to as extinction
Symptoms of posterior
parietal lobe damage
Contralateral neglect
Neglect for visual, auditory
and somethetic stimulation on
one side of the body or space
During recovery, patients go
through allesthesia and then
simultaneous extinction
Allesthesia - begins to
respond to the neglected
stimuli as if they were on the
other side of the body
Lesion most often in the
right inferior parietal lobe
Right intraparietal
sulcus and the right
angular gyrus
Object recognition
After right parietal lobe
lesions, patients are poor
at recognizing objects in
unfamiliar views
Apraxia
Movement disorder in which the loss
of movement is not caused by
weakness, inability to move, abnormal
muscle tone, intellectual deterioration,
or other disorders of movement
Ideomotor apraxia
Cannot copy serial
movements
More likely to be associated
with left parietal lesions
Constructional apraxia
Cannot copy pictures, build
puzzles, or copy a series of
facial movements
Associated with right
and left parietal lesions
Deficits in drawing
appear after damage to
the right parietal lobe
Spatial attention
Function of the parietal
lobe to selectively attend
to different stimuli
Disengagement
Shifting attention from
one stimulus to the next
Disorders of spatial cognition
Mental rotation requires:
Mental imaging of the stimulus
Manipulation of the image
LH deficit may result
from the inability to
generate the image
RH deficit may result
from the inability to
manipulate the image