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Definition
| the whole area you can see without moving your head or eyes |
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Definition
sharpness of vision - falls off towards the periphery of the visual field
(can't actually see color in periphery) |
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Definition
| light-sensitive receptor cells in the retina |
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Definition
| a process in interconnected neurons where each photoreceptor inhibits its neighbors at the edges of regions |
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Definition
| can enhance the perception of objects |
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Definition
| what the band of electromagnetic radiation is measured in |
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Definition
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Definition
| quanta of light energy with visible wavelengths |
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| retina --> primary visual cortex |
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Definition
| Visual pathways start and end at: |
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Definition
| where neural signals in the retina converge |
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Definition
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| the bending of light that is done by the cornea and forms the image |
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| adjust the focus of the eye by changing the shape of the lens |
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Definition
| the process of focusing the lens |
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Definition
| controls light entering the eye; an opening in the iris |
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Definition
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Term
1. Photoreceptors
2. Bipolar cells
3. Ganglion cells
4. Horizontal cells
5. Amacrine cells
(all but ganglion cells generate graded potentials) |
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Definition
| 5 cell types of the retina |
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Term
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Definition
| 2 types of photoreceptor cells |
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Definition
| receive input from photoreceptors and synapse on ganglion cells |
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Definition
axons of these form the optic nerve
- generate action potentials |
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Term
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Definition
| contact photoreceptors and bipolar cells |
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Term
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Definition
| contact bipolar and ganglion cells |
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Definition
| works in dim light (rods) |
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Definition
| requires more light, and allows color vision (cones) |
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Definition
the photopigment rods respond to
- cones use similar photopigments |
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Definition
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Term
| ...Retinal dissociates and the opsin is activated |
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Definition
| When light activates rhodopsin... |
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Definition
| What the visual system responds to |
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Term
1. Sensitivity - weak stimuli are amplified
2. Integration - of the stimulus over time increase sensitivity
3. Adaptation - to a wide range of light intensities |
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Definition
| 3 characteristics of the visual system that are accounted for by the processes needed to stimulate visual receptors |
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Term
1. Adjusting pupil size
2. Range Fractionation
3. Photoreceptor Adaptation |
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Definition
| 3 ways the visual system can deal with a wide range of intensities |
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Definition
| says that receptors with different thresholds handle different intensities |
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Term
1. The role of Ca2+
2. The level of photopigment
3. The availability of retinal chemicals for transduction |
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Definition
| 3 factors that contribute to photoreceptor adaptation |
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Definition
| where visual acuity is best; has a high density of cones |
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Definition
| where blood vessels enter and leave the eye |
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Definition
| due to a lack of photoreceptors in the optic disc |
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Definition
| a spot where nothing can be perceived; perceptual gap |
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Definition
| where the optic nerve crosses |
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Definition
| what the axons of the optic nerve are called after passing the optic chiasm |
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Term
| Lateral Geniculate Nucleus (LGN) |
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Definition
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Term
| Primary Visual Cortex (V1) |
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Definition
the region where most visual information first arrives
- perceives objects and events and is necessary in forming mental images |
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Term
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Definition
| axons of postsynaptic cells in the LGN form this and project to the occipital cortex |
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Definition
| another name for primary visual cortex |
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Definition
| visual cortical areas outside the striate cortex |
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Definition
| orderly mapping of the visual field |
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Definition
| steadily released by photoreceptors at rest (in the dark); depolarizes some bipolar cells and hyperpolarizes others |
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Definition
turning on light excites them
- light causes them to receive less glutamate, which normally inhibits them |
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Definition
turning off light in the center of the field excites the cells
- receive more glutamate and are depolarized in the dark |
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Term
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Definition
excited by on-center bipolar cell when light is turned on
(low glutamate) |
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Term
| Off-Center Ganglion Cells |
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Definition
| excited by off-center bipolar cells when light is turned off (high glutamate) |
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Term
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Definition
| How many layers does the lateral geniculate nucleus have? |
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Definition
four dorsal layers of the LGN
- small cells, small receptive fields |
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Definition
two ventral layers
- large cells, large receptive fields |
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Term
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Definition
| layers with very small cells, between the main layers |
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Term
1. P ganglion cells
2. M ganglion cells |
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Definition
| Two main types of retinal ganglion cells: |
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Term
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Definition
project to the parvocellular layer of the LGN
- correspond to the Photopic system |
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Term
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Definition
project to the magnocellular layer of the LGN
- corresponds to the scotopic intensity |
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Term
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Definition
| What type of receptive field visual cells in the LGN have? |
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Term
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Definition
respond to an edge or bar of a particular width, orientation, and location
- aka bar or edge detectors |
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Term
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Definition
| respond to a bar of a particular width and orientation, but the bar may be located anywhere in the visual field |
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Term
| Spatial-Frequency Filter Model |
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Definition
| emphasizes Fourier analysis of visual stimuli |
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Term
| Spatial Frequency of a Visual Stimulus |
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Definition
| the number of light-dark (or color) cycles per degree of visual space |
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Term
| V2, V4, and the Inferior Temporal Lobe |
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Definition
| 3 corteces that are involved in perception of form |
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Definition
| specialized for motion perception |
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Definition
| senses color and has a strong response to concentric and radial stimuli |
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Definition
can respond to illusory boundaries, and perceive complex relations among parts of the receptive fields
- adjacent to V1 and has similar properties |
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Term
| Inferior Temporal Area (IT) |
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Definition
respond to complex forms, including forms that the subject has learned to recognize
- receptive fields probably develop through experience and learning |
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Definition
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Term
1. Location in the Visual Field
2. Ocular Dominance
3. Orientation
4. Color |
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Definition
| 4 parts of a visual stimulus that V1 has representations for |
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Definition
| a region of cortex with greater synaptic input from one eye |
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Term
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Definition
| vertical columns are arranged in these; neurons in all layers respond better to one eye |
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Definition
| responds to rod-shaped stimuli of a particular orientation |
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Term
1. Brightness
2. Hue
3. Saturation |
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Definition
| 3 dimensions color is created in by the visual system |
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Definition
| varies from dark to light |
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Definition
| varies throughout all colors |
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Definition
| varies from full colors to gray |
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Definition
Color perception:
- three different types of cones
- Each responds to a different part of the spectrum
- Each has a separate pathway to the brain
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Term
| Opponent-Process Hypothesis |
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Definition
Color perception:
- Four unique hues and three opposed pairs of colors
- Three systems that produce opposite responses to different wavelengths
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Term
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Definition
| peak sensitivity at 420 nm |
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Term
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Definition
| peak sensitivity at 530 nm |
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Definition
| peak sensitivity at 560 nm |
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Term
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Definition
the cell has opposite firing responses to different regions of the spectrum (+L/-M)
- receive input from different types of cones, and record the difference |
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Term
1. Outputs go to other circuits for form, depth, and movement detection
2. Their peak sensitivities do not correspond to the wavelengths for the main colors |
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Definition
| 2 reasons spectrally opponent neurons are not color cells |
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Term
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Definition
| 2 things that stimulate brightness detectors |
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Term
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Definition
| 2 things that inhibit darkness |
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Term
1. Excellent Trichromatic Color Vision
2. Robust Dichromatic Color Vision
3. Feeble Dichromatic Vision
4. Minimal Color Vision |
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Definition
| Four categories of color vision in mammals: |
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Term
| diurnal primates and humans |
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Definition
| mammals with excellent trichromatic color vision |
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Term
| dogs, pigs, and new world monkeys |
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Definition
| Mammals with robust dichromatic color vision |
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Term
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Definition
| Mammals with feeble dichromatic vision |
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Term
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Definition
| Mammals with minimal color vision |
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Term
1. Ventral Processing Stream
2. Dorsal Processing Stream |
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Definition
| 2 main processing streams originate in primary visual cortex |
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Term
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Definition
| for identifying objects (what) |
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Term
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Definition
| for assessing the location of objects (where) |
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Term
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Definition
| can cause difficulty in using vision to reach for an object |
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Term
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Definition
active in premotor cortex when watching another perform an action
- transforms visual information into knowledge |
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Term
1. Three different types of cones
2. Each responds to a different part of the spectrum
3. Each has a separate pathway to the brain |
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Definition
3 parts of the Trichromatic Hypothesis |
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Term
1. Four unique hues and three opposed pairs of colors
2. Three systems that produce opposite responses to different wavelengths |
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Definition
| 2 parts of the Opponent-Process Hypothesis |
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