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29 Cards in this Set
- Front
- Back
Layers of LGN
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Magnocellular (2)
Parvocellular (4) koniocellular interposed between principal layers |
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Properties of LGN neurons
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-functionally similar to retinal ganglion cells
-moncular -concentric receptive fields |
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mLGN cells
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-process M retinal ganglion cell inputs
-large center-surround receptive fields -color insensitive -sensitive to movement of visual stimuli |
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pLGN cells
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-process P retinal ganglion cell inputs
-small center surround receptive fields -color sensitive -detect contrasts that form basis of shape/form discrimination |
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kLGN
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-process P retinal ganglion cells
-behave lie P RGCs -smallest concentric receptive fields -stronger color sensitivity that P RGCs |
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Striate cortex
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includes calcarine cortex and extends around occipital pole to include lateral aspect of caudal occipital lobe
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LGN neurons......
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send their axons in the internal capsule to the occipital lobe where they terminate in the striate cortex
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Path of LGN axons in Sublenticular segment
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form Meyer's loop, travel up to the inferior bank of striate cortex and terminate (superior visual field)
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Path of LGN axons in Retrolenticular segment
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pass superiorly t hrough the parietal lobe to end in the superior bank of striate cortex (inferior visual field)
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V1 Blob Cells
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resemble kLGN neurons, color sensitive, monocular, small concentric receptive fields, found in clusters or "blobs," special target of kLGN axon terminals, color processing cells of V1
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V1 Interblob Cells
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-binocular
-NOT color sensitive -elongated receptive fields -found around the V1 blob cells -ocular dominance -orientation specificity |
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Location specific V1 interblob cells
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-p-stream info
-reponsds best when the stimulus is in a specific location of the receptive field (location specificity) -poor response to movement -shape/form processing cells and location processing cells of v1 |
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Movement sensitive v1 interblob cells
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-respond best to moving stimuli with no preference for direction of movement
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Direction specific V1 interblob cells
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-preference for movement in a particular direction
-M stream info -detects object movement and direction/velocity "motion detectors" |
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Which is weaker: long range connection or short range connections?
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long range connections--exclusively excitatory and tend to connect cortical columns that encode similar features., mediate contextual interactions
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What is the locus of mid-level vision?
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Extrastriate cortex
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What is included in the extrastriate cortex/
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all of the occiptial lobe areas surrounding the primary visual cortex
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What modulates the neurons in the extrastriate visual cortex?
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extraretinal factors such as attention or memory
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What does damage to the extrastriate cortex cause?
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higher order visual perceptual deficits including failure to recognize objects, colors, and or movement of objects
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What sends projections to the extrastriate cortex?
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V1 primary visual corrtex (info about color, shape/form, location and motion
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What are the boundaries of the visual association cortex?
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extends anteriorly from the extrastriate cortex to encompass adjacent areas of the posterior parietal lobe and much of the posterior temporal lobe
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Wht does the visual association cortex receive input from?
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via extrastriate cortex
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Dorsal Stream Properties
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-parietal assoc cortex, superior and middle temporal visual assoc cortex
-binocular receptive fields -process P channel info about object location -process M channel info about object movement |
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What are dorsal stream neurons responsible for?
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Our sense of:
-spatial orientation -binocular fusion/depth perception -location, direction of motion and velocityof objects in space |
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Ventral stream properties
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-neurons in inferior temporal visual assoc cortex
-process p channel info about object color and form |
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Ventral stream is responsible for.....
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Our abilities to
-recognize objects and color -learn and rememberf visual objects -processes info about the "what" of visual stimulus -damage results in perception, attention, and learning/memory deficits |
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What kind of information do the optic radiation fibers traveling the most direct course carry?
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info about the central visual field
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What do sublenticular optic radiations carry?
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info abou superior hemifield
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What do retrolenticular optic radiations carry?
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info about inferior hemifield
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