spatial cognition Flashcards
Parietal cortex
has key components of spatial processing
subdivisions
anterior lobe
posterior parietal cortex
anterior parietal lobe
somatosensory representations (not considered part of the dorsal stream proper)
posterior parietal cortex (PPC)
multisensory and crucial in many aspects of spatial cognition
intraparietal sulcus
separates the superior and inferior parietal lobules
middle temporal and medial temporal areas
contribut to motion
where does the dorsal stream receive visual info from
primary visual cortex and somatosensory cortex and vestibular system (info about position of the body in space)
central sulcus
separates parietal and frontal lobe
parieto-occipital sulcus
seperates parietal and occipital lobes
what are the three pathways of the dorsal stream
- connects the parietal cortex with prefrontal cortex
- connects the parietal cortex with premotor cortex
- connects the parietal cortex with medial temporal cortex (includes hippocampus and parahippcampal cortex
function of the connection between the parietal cortex with prefrontal cortex
supports spatial working memory
function of the connection between the parietal cortex with premotor cortex
supports visually guided actions such as reaching and grasping
function of the connection between the parietal cortex with medial temporal cortex
supports spatial navigation ie/ wayfinding
cells of the dorsal stream
responsive to attributes of visual info that are useful for processing spatial relations
these cells do not play a large role in object recognition as they are not sensitive to form, colour, and items positions in central vision (where acuity is the highest)
coding for the three dimensions of space
the brain is able to code for the vertical, horizontal and depth dimensions
the retinal images that the brain receives are 2D and the depth dimension must be computed in the cortex
distinguishing left and right
cortex of left parietal lobe may be involved
binocular disparity
how depth is determined
not provided directly by retinotopic map
used via comparing images from both eyes
cells in the primary visual cortex are sensitive to different amounts of binocular disparity, and provide important info about depth for use by the dorsal stream regions
motion parallax
refers to the fact that as you move through an environment near objects and displaced more on your retina than objects that are far away
ie/ car moving and building behind not so much
monocular depth cue - input only perceived by one eye
egocentric reference frames
specify an object’s location in relation to some aspect of the self (body, head, eye, etc.)
neglect associated with right parietal lobe damage
allocentric reference frame
specify an object’s location in relation to other objects, independent of one’s own location
object centered neglect associated with
right hemisphere middle and inferior lobe damage
akinetopsia
selective deficits in motion perception
area MT (V5)
important for perceiving motion
MST
involved for coding for more complex motion like optic flow
optic flow
the pattern of movement of images on your retina as you actively move through an environment
depends on your speed and direction as well as the spatial relationship of each scene element in relation to the body
understanding that when you are moving towards smt it is getting closer
sources that provide the visual system with info about eye movements
motor regions of the brain are planning to move the eyes (sends a corollary discharge)
sensory receptors within the eye muscles provide ongoing feedback about changes in the position of the eye. ie/ i know my eyes are moving, so the object might not be
optic ataxia
a disorder of visually guided reaching
result of parietal lobe damage
usually the most pronounced in the peripheral region rather than the central visual field
deficit is most profound for real-time integration of vision and motion
may result from an inability
to integrate cues involving eye-gaze directions (perception) and reaching direction (action)
sensory-motor integration within subregions of the parietal cortex
cells in the lateral intraparietal cortex code the location of the stimulus first and then shift to the location of the planned movement
lateral intraparietal region
coding of space for intended eye movements
parietal reach region
disrupting activity here produces symptoms similar to optic ataxia
route based strategy for spatial navigation
the person’s understanding is represented as a sequence of steps, often specified in terms or particular landmarks
map based strategy for spatial navigation
involves having an allocentric understanding od how all the different parts of the landscape relate to one another
egocentric disorientation
involves the inability to represent the location of object in relationship to the self
patients with difficulties with navigation because they are unable to represent spatial relations
landmark agnosia
patients lose the ability to recognize certain landmarks that are usually used for navigation (route-based navigation becomes difficult)
if you can’t tell what smt is, how do you know if yu got there
deficits typically occur following damage to the ventral stream
parahippocampal place area
codes for landmarks relative to navigation
retrosplenial complex
determines a person’s location within a familiar spatial environment
location no matter where you are facing
medial temporal lobe
contains a map-like allocentric representation of familiar environements
anterograde disorientation
trouble constructing new environmental representions, but can still navigate previously learned environments
associated with PPA damage
heading disorientation
trouble understanding one’s own orientation (heading), butn can recognize landmarks and understand relations between locations in space
associated with RSC damage
