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65 Cards in this Set
- Front
- Back
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Sensory receptors
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A specialized neuron that detects a particular category of physical events
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Sensory transduction
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a process by which sensory stimuli are transduced into slow, graded receptor potentials
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Receptor potential
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a slow, graded electrical potential produced by a receptor cell in response to a physical stimulus
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How much of the cortex is devoted to vision senses?
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20% of the cortex
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What is the wavelength of light our eyes detect?
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380-760 nm is visible
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On what three levels to we perceive light?
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1. Hue (wavelength)
2. Brightness (intensity) 3. Saturation (purity) |
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Vergence movements:
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the cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas
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Saccadic movement
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the rapid, jerky movement of the eyes used in scanning a visual scene
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Pursuit movement
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the movement that eye makes to maintain an image of a moving object
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-Accommodation
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CHANGING THICKNESS OF LENS TO FOCUS IMAGE ON RETINA
changes in the thickness of the lens of the eyes, accomplished by ciliary muscles, that focus images of near or distant objects on the retina |
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Retina
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the neural tissue and photoreceptive cells located on the inner surface of the posterior portion of the eye
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Rods
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one of the receptor cells of retina, sensitive to light of low intensity
120 MILLION |
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cones
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one of the receptor cells of retina, maximally sensitive to 1 of 3 different wavelengths of lights and thus color vision, daytime vision
LOTS IN FOVEA 20 MILLION |
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Photoreceptor
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one of receptor cells of retina, transduces photic energy into electric potentials
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Foveal
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the region of retina that mediates the most acute vision of birds and higher mammals. Color sensitive cones constitute the only type of photoreceptor found in the fovea
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Bipolar cell
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a bipolar neuron located in the middle layer of retina, convey info from photoreceptor to ganglion cell
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Ganglion cell:
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a neuron located in the retina that receives visual info from bipolar; axons give way to optic nerve
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Horizontal cell:
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a neuron in the retina that interconnect adjacent photoreceptors and the outer processes of bipolar cells
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Amacrine cell
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a neuron in the retina that interconnects adjacent ganglion cells and the inner processes of bipolar cells
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Lamella
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a layer of membrane containing photopigments; found in rods and cones of retina
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Photopigments
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a protein dye bonded to retinal, a substance derived from Vitamin A, responsible for transduction of visual info
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Opsin
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a class of protein that, together with retinal makes photopigments
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Retinal
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a chemical synthesized from vitamin A, joins with an opsin to form a photopigment
"CARROTS GOOD FOR YOUR EYES" |
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-Rhodopsin
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rhod-rose; pinkish hue
- LIGHT BREAKS INTO 2 CONSTITUENTS AND THE SPLIT MAKES A POTENTIAL * |
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dhow do depolarizations affect the release of neurotransmitters?
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INCREASE RELEASE!!
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How do hyperpolarizations affects the release of neurotransmitters?
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DECREASE RELEASE!
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dorsal lateral genicular nucleus (LGN):
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very important for vision
“bent knee”; a group of cell bodies w/in lateral genicular body of thalamus; receives inputs from retina and project to primary visual cortex o Contains 6 layers of neurons |
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Magnocellular layer
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one of the inner two layers of neurons in DLG nucleus; transmits info necessary for perception of form, movement, depth and small difference in brightness to PVC
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Parvocellular layer
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one of the four outer layers of neurons in DLG nucleus; transmits info necessary for perception of color and fine details to PVC
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Koniocellular layer
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one of the sublayers of neurons in the DLG found ventral to each of the magnocellular and parvocellular layers; transmits info from short wavelength “blue” cones to PVC
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Calcarine fissure
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a horizontal fissue on the inner surface posterior cortex, location of PVC
STRIATE CORTEX = PVC |
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Optic Chiasm
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a cross shaped connection between the optic nerves, located base of brain, just anterior to pituitary gland
o Contralateral o Not correct say receive SOLE from other side o Fibers also go to hypothalamus (24 hour cycles) and optic tectum (eye movements, visual stimuli attention, size of pupils) |
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Receptive field
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the portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron
- Field that neuron “sees” |
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What is the trichromatic theory?
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Photoreceptors absorb different light wavelength depending on particular opsin it has
Short, medium, long = “blue”, “green”, “red” |
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Protanopia
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an inherited form of a defective color vision in which red & green hues are confused, “red” cones filled with “Green” cone opsin
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Deuteranopia
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an inherited form of a defective color vision in which red and green hues are confused; “green” cones filled with “red” cone opsin
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Tritanopia
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an inherited form of defective color vision in which hues with short wavelengths are confused, “blue” cones lacking or faulty
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What is opponent-process coding?
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Red light stimulates red cone = red-green ganglion excited = signals red
Green light stimulates green cone = red-green ganglion inhibited = signals green Yellow light stimulates red and green equally =cancel each other out = signals yellow Blue light stimulates blue cone = yellow-blue ganglion inhibited = signals blue This explains why some colors not mix! |
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Negative after-image
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the image seen after a portion of the retina is expose to an intense visual stimulus; consists of colors complementary to those of the physical stimulus
- Rebound effects after stimulus is gone |
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Complementary colors
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colors that make white or gray when mixed together
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How much of striate cortex devoted to analysis of foveal region?
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25% of striate cortex devoted to analysis of fovea
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What are three types of cells involved in the perception of orientation and movement?
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Simple: ORIENTATION ONLY
Complex: ORIENTATION AND MOVEMENT Hypercomplex: ENDS |
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Sine Wave Grating
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a series of straight parallel bands varying continuously in brightness according to a sine wave function, along a line perpendicular to their lengths
- Looks like a series of fuzzy, unfocused lines - b/c stimulus varies in size according to how close from eye, use visual angle instead of physical distance (when lines closer together, angle smaller) |
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Spatial frequency:
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a relative width of the bands in a sine-wave grating, measure in cycles per degree of visual angle
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What is high-frequency information?
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small objects, details within large object, large object with sharp edges
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What is low-frequency information?
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larges areas of light and dark
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Which frequency provides the most important information?
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Low-frequency provides details; high frequency looks pixelated!
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Retinal Disparity:
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the fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides basis for stereopsis (
“3d movie”) |
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Cytochrome oxidase (CO) blob
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central region of module of the primary visual cortex, revealed by a stain for cytochrome oxidase (enzyme in mitochondria); contains wavelength neurons; part of the parvocellular system
- In visual cortex |
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What is the division of the visual cortex?
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2 areas: V1 and V2
V2 has 3 stripes: thick, thin and pale V1 has blobs |
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Ocular dominance
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the extent to which a particular neuron receives more input from one eye or the others
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Extrastriate cortex
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a region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to the inferior temporal cortex
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Dorsal stream
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A system of interconnected regions of visual cortex involved in the perception of SPATIAL LOCATION, beginning with the striate cortex and ending with the posterior parietal cortex
• GUIDES NAVIGATION AND SKILLED MOVEMENTS DIRECTED TOWARD OBJECT • Posterior parietal cortex: the highest level of the dorsal stream of the visual association cortex; involved in perception of movement and spatial location • Dorsal from magnocellular - Color blind - All animals have this |
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Ventral stream
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• Definition: a system of interconnected regions of the visual cortex involved in the perception of FORM; beginning with the striate cortex and ending with the inferior temporal cortex
• SIZE, SHAPE, COLOR AND TEXTURE • Inferior temporal cortex: the highest level of the ventral stream of the visual association area; involved in perception of objects, incl people’s bodies and faces • Ventral from parviocellular/magnocellular - This sees fine details - Only primates have |
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Color constancy
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the relative constant appearance of the color of objects viewed under varying lighting conditions
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Cerebral achromatopsia
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inability to discriminate among different hues; caused by damage to area V8 of visual association cortex
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Visual Agnosia
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deficits in visual perception in the absence of blindness; caused by brain damage
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prosopagnosia
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failure to recognize people from faces
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Laeral occipital complex:
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a region of the extrastriate cortex, involved in perception of objects other than people’s bodies or faces
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Fusiform face area (FFA):,
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a region of the visual association cortex located in the inferior temporal; involved in perception of faces and other complex objects that require expertise to recognize
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Extrastriate body area (EBA):
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a region of the visual association cortex located in the lateral occipitotemporal cortex; involved in perception of the human body and body parts other than faces
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Parahippocampal place area (PPA):
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a region of limbic cortex on the medial temporal lobe; involved in perception of particular places “Scenes”
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Optic Flow
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the complex motion of points in the visual field caused by relative movement between the observer and environment; provides information about the relative distance of objects from the observer and of the relative direction of movement
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Akinetopsia
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inability to perceive movement, caused by damage to area V5 (also: MST)
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Intraparietal sulcus (IPS)
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the end of the dorsal stream of the visual association cortex; involved in perception of location, visual attention, and control of eye and hand movements
LIP/VIP = saccadic eye movements VIP/MIP = reaching and pointing AIP = grasping, manipulating hand CIP = depth |
