Quiz
Visual System II and III
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1The receptive field of an individual sensory neuron is the [blank_start]particular region of sensory space[blank_end] (eg the visual field, or body surface) in which [blank_start]a stimulus affects the firing[blank_end] of that neuron.
- Aparticular region of sensory space
- Ba stimulus affects the firing
2Receptive fields in the retina are [blank_start]circular[blank_end] in shape and defined in terms of [blank_start]degrees of visual space[blank_end] (from hundredths of a degree in the fovea to tens of degrees in the periphery).
- Acircular
- Bdegrees of visual space
3Ganglion cell receptive fields are [blank_start]circular[blank_end], with [blank_start]antagonistic[blank_end] (opponent) responses between [blank_start]center and surround[blank_end], ie the show [blank_start]center surround[blank_end] organization
- Acircular
- Bantagonistic
- Ccenter and surround
- Dcenter surround
4Receptive fields are either "[blank_start]on-center[blank_end]" or "[blank_start]off-center[blank_end]"
- Aon-center
- Boff-center
5The two types of center-surround receptive fields exhibited by retinal ganglion cells are created in a two step process:
- First, the [blank_start]opponent center surround aspect[blank_end] is created by mutual inhibition among photoreceptors that is produced by [blank_start]horizontal cells[blank_end]
- Second, the [blank_start]on- and off- center aspect[blank_end] is created by [blank_start]bipolar cells[blank_end] which show opposite responses to the Glu released by their receptor (Ie [blank_start]bipolar[blank_end] cells express different Glu receptors)- Aopponent center surround aspect
- Bhorizontal cells
- Con- and off- center aspect
- Dbipolar cells
- Ebipolar
6Ganglion cells inherit the on- and off-center aspect of their receptive field responses from [blank_start]bipolar[blank_end] cells.
- Abipolar
7On-center bipolar cells have [blank_start]metabotropic glu receptors[blank_end] (activation of which leads to K+ efflux). Thus, on-center bipolar cells respond best when their receptor input releases [blank_start]less Glu[blank_end].
- Ametabotropic glu receptors
- Bless Glu
8Off-center bipolar cells have [blank_start]ionotropic Glu receptors[blank_end] (activation leads to Na+ influx). Thus, off-center cells respond best when their photoreceptor input releases [blank_start]more Glu[blank_end].
- Aionotropic Glu receptors
- Bmore Glu
9Ganglion cells (and their bipolar inputs) respond weakly if a stimulus activates their [blank_start]entire receptive field[blank_end].
- Aentire receptive field
10Ganglion cells are sensitive to spectral contrasts by virtue of their opponent, center surround organization. The on and off center responses create a [blank_start]push-pull system[blank_end] that provides [blank_start]sensory redundancy[blank_end] and [blank_start]decreases[blank_end] sensitivity to common rate changes (eg due to body temperature).
- Apush-pull system
- Bsensory redundancy
- Cdecreases
11Ganglion cells with inputs mainly from rods (in peripheral retina) are sensitive to [blank_start]light and dark[blank_end]
- Alight and dark
12Ganglion cells with inputs primarily from cones (in the fovea) are sensitive to [blank_start]color contrasts[blank_end]
- Acolor contrasts
13Most ganglion cells with cone inputs are [blank_start]color-opponent[blank_end]. The two types of color-opponent cells are:
- [blank_start]red-green[blank_end]
- [blank_start]blue-yellow[blank_end] (where [blank_start]yellow[blank_end] sensitivity is created by the sum of inputs from [blank_start]red and green cones[blank_end])- Acolor-opponent
- Bred-green
- Cblue-yellow
- Dyellow
- Ered and green cones
14M cells:
- [blank_start]peripheral[blank_end] retina (~100,000)
- [blank_start]large[blank_end] cell bodies and large RFs
- [blank_start]coarse[blank_end] resolution
- [blank_start]inputs[blank_end] from 1000s of rods and cones: convey light vs dark information
- [blank_start]rapid[blank_end] adaption and conduction of APs
- [blank_start]Motion[blank_end] response better than stationary
- optimized for [blank_start]large-scale, low-contrast moving pattern[blank_end]s- Aperipheral
- Blarge
- Ccoarse
- Dinputs
- Erapid
- FMotion
- Glarge-scale, low-contrast moving pattern
15P cells:
- [blank_start]central[blank_end] retina (esp. fovea) (~1 million)
- [blank_start]small[blank_end] cell bodies and small RFs
- [blank_start]Fine[blank_end] resolution
- inputs from ~ [blank_start]1 cone[blank_end] - convey color
- [blank_start]slow[blank_end] adaption and conduction of APs
- [blank_start]stationary[blank_end] targets better than moving
- optimized for [blank_start]small-scale high contrast fine patterns[blank_end]- Acentral
- Bsmall
- CFine
- D1 cone
- Eslow
- Fstationary
- Gsmall-scale high contrast fine patterns
16Optics of eye project [blank_start]reversed and upside-down image[blank_end] of monocular visual field onto each retina
- Areversed and upside-down image
17Optic nerves exit each eye and project [blank_start]bilaterally[blank_end] to the [blank_start]lateral geniculate nucleus (LGN)[blank_end] of the (visual) thalamus.
- Abilaterally
- Blateral geniculate nucleus (LGN)
18Fibers from [blank_start]temporal hemi retina[blank_end], which views the contralateral half of a monocular visual field, projects to [blank_start]ipsilateral LGN[blank_end].
- Atemporal hemi retina
- Bipsilateral LGN
19Fibers from the [blank_start]nasal hemi retina[blank_end], which views the ipsilateral half of a monocular visual field, cross the midline ([blank_start]decussate[blank_end]) in the [blank_start]optic chiasm[blank_end], and project to [blank_start]contralateral LGN.[blank_end]
- Anasal hemi retina
- Bdecussate
- Coptic chiasm
- Dcontralateral LGN.
20LGN on each side projects [blank_start]ipsilaterally[blank_end] to the [blank_start]primary visual cortex.[blank_end]
- Aipsilaterally
- Bprimary visual cortex.
21Information from each visual hemi field processed in [blank_start]contralateral[blank_end] hemisphere of [blank_start]visual cortex[blank_end].
- Acontralateral
- Bvisual cortex
22Approx [blank_start]90[blank_end]% of retinal ganglion cells project to the LGN. The remainder (not M or P cells) project to the [blank_start]hypothalamus[blank_end], [blank_start]pre-tectum[blank_end], and [blank_start]superior colliculus[blank_end].
- A90
- Bhypothalamus
- Cpre-tectum
- Dsuperior colliculus
23Primate LGN is organized into [blank_start]6[blank_end] distinct layers (laminae):
- Layers 1 and 2: [blank_start]Magnocellular[blank_end] - large cells, input from M-RGCs
- Layers 3-6: [blank_start]Parvocellular[blank_end] - small cells, input from P-RGCs- A6
- BMagnocellular
- CParvocellular
24LGN cells in each layer are [blank_start]monocular[blank_end] because they receive RGC input from hemi retina of [blank_start]only one eye[blank_end]:
- Layer 1, 4, 6: [blank_start]contralateral nasal[blank_end] hemi retina
- Layer [blank_start]2, 3, 5[blank_end]: ipsilateral temporal hemi retina- Amonocular
- Bonly one eye
- Ccontralateral nasal
- D2, 3, 5
25Each lamina is [blank_start]retinotopically organized[blank_end] (adjacent points of the visual field are represented in adjacent regions). Each point in contralateral visual space is [blank_start]precisely aligned[blank_end] across layers (with the fovea over-represented).
- Aretinotopically organized
- Bprecisely aligned
26Laminae are [blank_start]retinotopic[blank_end]: orderly space map of [blank_start]contralateral[blank_end] visual hemi field in [blank_start]each layer[blank_end] of LGN
- Aretinotopic
- Bcontralateral
- Ceach layer
27Cells are [blank_start]monocular[blank_end]: segregation of [blank_start]RGC input[blank_end] from each eye in [blank_start]overlapping laminae[blank_end] of LGN
- Amonocular
- BRGC input
- Coverlapping laminae
28Receptive fields are [blank_start]circular/opponent[blank_end], similar to the RGC inputs
- Acircular/opponent
29[blank_start]Visual cortex[blank_end] includes many interconnected cortical areas processing visual information in the [blank_start]occipital, parietal, and temporal lobes[blank_end]. Primate visual cortex occupies more than [blank_start]50[blank_end]% of the neocortex, reflecting importance of vision for behavior.
- AVisual cortex
- Boccipital, parietal, and temporal lobes
- C50
30LGN projects to [blank_start]primary visual cortex[blank_end] (aka [blank_start]striate cortex, V1, Brodman's area 17[blank_end]) in the [blank_start]occipital lobe[blank_end] (caudal cortical pole).
- Aprimary visual cortex
- Bstriate cortex, V1, Brodman's area 17
- Coccipital lobe
31Neocortex has [blank_start]6[blank_end] layers labeled [blank_start]I to VI[blank_end] from [blank_start]top (pia surface) to bottom[blank_end].
- layer [blank_start]IV[blank_end] receives inputs from the thalamus
- layer [blank_start]interconnected vertically[blank_end], forming cortical columns, the fundamental [blank_start]processing unit of the cortex[blank_end]- A6
- BI to VI
- Ctop (pia surface) to bottom
- DIV
- Einterconnected vertically
- Fprocessing unit of the cortex
32LGN cells project to [blank_start]lowest part of layer IV (layer IV-C)[blank_end] of striate cortex
- P and M cells project to [blank_start]different subdivisions of layer IV-C[blank_end]
- inputs from the two eyes [blank_start]terminate side-by-side[blank_end]- Alowest part of layer IV (layer IV-C)
- Bdifferent subdivisions of layer IV-C
- Cterminate side-by-side
33V1 is [blank_start]retinotopic[blank_end]; the [blank_start]central[blank_end] (~4 degree) visual space (esp fovea) is heavily over-represented
- Aretinotopic
- Bcentral
34By and large, the receptive fields of neurons of layer IVC ([blank_start]the input layer[blank_end] of [blank_start]primary visual cortex; striate cortex; V[blank_end]1) are similar to those of their LGN inputs and, in turn, of retinal ganglion cells.
- Athe input layer
- Bprimary visual cortex; striate cortex; V
35Receptive fields of neurons of layer IVC are
- [blank_start]monocular[blank_end]
- [blank_start]circular[blank_end]
- [blank_start]center-surround[blank_end]- Amonocular
- Bcircular
- Ccenter-surround
36retinal inputs from the left and right eye (with receptive fields in the same spot in space) [blank_start]remain segregated in the LGN[blank_end] and the input layer of visual cortex (layer IVC)
- Aremain segregated in the LGN
37Beyond layer IVC, the signals from the two eyes are [blank_start]combined at the cellular level[blank_end]; that is, neurons in most layers of visual cortex are [blank_start]binocular[blank_end]. However, the input from one eye is usually dominant; the bands of cells extending through the thickness of the striate cortex are called [blank_start]ocular dominance columns[blank_end].
- Acombined at the cellular level
- Bbinocular
- Cocular dominance columns
38Cells in layer IVC are [blank_start]monocular[blank_end] and have receptive fields with [blank_start]opponent center-surround organization[blank_end].
- Amonocular
- Bopponent center-surround organization
39Many neurons beyond layer IVC are [blank_start]simple[blank_end] cells.
- [blank_start]rectangular receptive field[blank_end]
- [blank_start]on and off regions[blank_end], like cells in layer IVC
- neurons are [blank_start]orientation-selective[blank_end] and location sensitive
- many are [blank_start]binocular[blank_end]- Asimple
- Brectangular receptive field
- Con and off regions
- Dorientation-selective
- Ebinocular
40Simple cells can be constructed simply from the [blank_start]convergence of center surround inputs[blank_end]. [blank_start]Optimal stimulus for their elongated RF[blank_end]: [blank_start]edge, bar, or grating[blank_end] precisely oriented and placed at the [blank_start]boundary[blank_end] of on and off region of RF.
- Aconvergence of center surround inputs
- BOptimal stimulus for their elongated RF
- Cedge, bar, or grating
- Dboundary
41Response may also be [blank_start]direction and velocity selective[blank_end] for visual stimuli moving across RF of simple cells.
- Adirection and velocity selective
42[blank_start]V1[blank_end] neurons show a range of optimal stimulus orientations. As an electrode passes parallel to the surface, the preferred orientation shifts progressively forming [blank_start]orientation columns.[blank_end]
- AV1
- Borientation columns.
43Cortical modules (or hyper columns) consist of:
- [blank_start]pairs of ocular dominance columns[blank_end]
- [blank_start]many orientation coumns[blank_end]
- [blank_start]blobs and inter blob regions[blank_end]- Apairs of ocular dominance columns
- Bmany orientation coumns
- Cblobs and inter blob regions
44Higher order neurons that prefer the same orientation as simple cells may also be sensitive to the line [blank_start]over larger areas of visual space[blank_end] (complex cells), to the line's [blank_start]length[blank_end] (hyper complex), and/or to [blank_start]binocular disparity.[blank_end]
- Aover larger areas of visual space
- Blength
- Cbinocular disparity.
45Module is [blank_start]necessary and sufficient[blank_end] for analysis of each point in visual space.
- Anecessary and sufficient
46Staining for the mitochondrial enzyme [blank_start]cytochrome oxidase[blank_end] (CO) reveals patches of more (blobs) or less densely labeled cells (inter-blob) in [blank_start]V1[blank_end].
- Acytochrome oxidase
- BV1
47Blobs most apparent in [blank_start]superficial layers II and III.[blank_end]
- Asuperficial layers II and III.
48Both blobs and interblob regions receive their dominant input from [blank_start]P type[blank_end] cells. [blank_start]M type[blank_end] cells project to [blank_start]layer IVB[blank_end] and then out of V1 (to [blank_start]extrastriate cortex[blank_end]).
- AP type
- BM type
- Clayer IVB
- Dextrastriate cortex
49Functional significance:
- neurons in blobs process [blank_start]color[blank_end]
- neurons in inter blobs process [blank_start]form[blank_end]- Acolor
- Bform
50Evidence suggests that there are two major parallel output pathways (streams) from V1 to extrastriate cortex:
- dorsal: [blank_start]M cells; motion/space[blank_end]
- ventral: [blank_start]P cells; color and form[blank_end]- AM cells; motion/space
- BP cells; color and form
51[blank_start]MST[blank_end] responds best to global motion patterns. Different cells are selective for [blank_start]apparent movement heading[blank_end]. May be important for [blank_start]navigation in space[blank_end], distinguishing [blank_start]self motion from object motion.[blank_end]
- AMST
- Bapparent movement heading
- Cnavigation in space
- Dself motion from object motion.
52[blank_start]Parietal[blank_end] cortex lesions lead to selective impairments of spatial processing:
- akinetopsia: [blank_start]selective inability to perceive motion[blank_end]
- optic ataxia: [blank_start]impairment of visually guided reaching[blank_end]
- hemi neglect syndrome: perceptual unawareness of the [blank_start]half of visual space contralateral[blank_end] to the lesion- Aselective inability to perceive motion
- Bimpairment of visually guided reaching
- Chalf of visual space contralateral
- DParietal
53[blank_start]Inferotemporal[blank_end] cortex cells have very large RFs (often bilateral) that include fovea. Large RF may be important for recognizing [blank_start]objects regardless of orientation[blank_end] in space ([blank_start]position invariance[blank_end]).
- AInferotemporal
- Bobjects regardless of orientation
- Cposition invariance
54Specific deficits occur with lesions to ventral stream. Examples:
- achromatopsia: [blank_start]loss of color vision[blank_end] ([blank_start]V4[blank_end] lesion)
- prosopagnosia: [blank_start]failure to recognize familiar faces[blank_end] ([blank_start]IT[blank_end] lesion). (may play a role in autism).- Aloss of color vision
- BV4
- Cfailure to recognize familiar faces
- DIT
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- Description
- Quiz on Visual System II and III, created by Hannah Miller on 10/11/2019.
- Author
- Hannah Miller
- Language
- English
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