Term
| Fundamental components of the visual system: |
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Definition
| eye, retina, optic nerves, optic chiasm, optic tract, lateral geniculate nucleus, primary visual cortex, extrastiate visual cortex |
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Term
| Every nerve impulse has to stop at the ______ before getting to the cortex. |
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Definition
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| The first stop for visual signals leaving the retina is the: |
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Definition
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Definition
| the opening that allows light to enter the eye and strike the retina |
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Definition
| the color part of your eye that regulates the size of the pupil |
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Definition
| clear sheet in front of the pupil and iris |
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Definition
| the white of your eye, 95% of your eye |
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Definition
| the lining of the iside of the eyelid |
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Definition
| six individual muscles on each eye |
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Definition
| contains the axons that travel to the LGN |
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Term
| The _______ is the most sensitive area on your body |
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Definition
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Definition
| changes shape to bring into focus |
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Definition
| muscle that pulls on lens to change shape, attached by zonule fibers |
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Definition
| fluid in the anterior chamber, between cornea and lens |
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Definition
| fluid in the posterior chamber between lens and retina |
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Definition
| lines the entire posterior wall |
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Term
| 80% of focusing is done by the ________. |
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Definition
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Term
| What instrument is used to look at the retina? |
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Definition
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Term
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Definition
| the pit or depression in the retina at the center of the macula; in humans, the fovea contains only cone photoreceptors and is specialized for high-acuity vison. |
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Definition
| the location on the retina where optic nerve axons leave the eye; also called optic nerve head. |
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Term
| Which side of the retina is 1/3 of the retina? |
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Definition
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Term
| Which side of the retina is the optic disk on? |
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Definition
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Definition
| the focusing of light by changing the shape of the eye's lens |
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Term
| The ciliary muscles pull harder when looking at ______ points. |
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Definition
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Term
| Ciliary muscles relax when looking at _________ points. |
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Definition
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Definition
| a bright light shown into one eye causes both eyes to contrict |
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Term
| A bright light shown into an eye causes the pupil to |
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Definition
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Term
| Both eyes can see over _____ degrees |
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Definition
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Term
| Each eye can see over _____ degrees. |
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Definition
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Term
| Why can't we see 300 degrees if each eye can see 150 degrees each? |
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Definition
| because we have binocular vision |
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Term
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Definition
| the ability of the visual system to distinguish between two nearby points |
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Term
| What are the five basic cell types |
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Definition
| Photoreceptors, bipolar cells, ganglion cells, horizonal cells, and amacrine cells |
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Term
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Definition
| a specialized cell in the retina that transduces light energy into changes in membrane potential |
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Definition
| in the retina, a cell that connects photoreceptors to ganglion cells. |
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Definition
| a cell in the retina that receives input from the bipolar cells and sends an axon into the optic nerve |
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Definition
| a cell in the retina of the eye that projects neurites laterally in the outer plexiform layer |
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Definition
| a neuron in the retina of the eye that projects neurites laterally in the inner plexiform layer. |
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Term
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Definition
| the retina over exaggerates edges/borders |
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Term
| What are the six layers in the retina? |
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Definition
| Ganglion cells, inner plexiform, inner nuclear, outer plexiform, outer nuclear, photoreceptor outer segments |
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Term
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Definition
| where the cell bodies are |
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Term
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Definition
| where the synapses and axons are |
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Term
| What are the two types of retinal layers |
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Definition
| nuclear and plexiform layers |
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Term
| Epithelium in humans ________ light. |
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Definition
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Term
| What are the two major parts of the photoreceptor? |
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Definition
| outer segment (the photosensitive part), and the inner segment (contains the cell body |
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Term
| What are the two types of photoreceptors? |
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Definition
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Term
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Definition
| a photoreceptor in the retina containing rhodopsin and specialized for low light levels |
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Term
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Definition
| a photoreceptor in the retina containing one of three photopigments that are maximally sensitive to different wavelengths of light. Cones are concentrated in the fovea, specialized for daytime vision and responsible for color vision. |
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Term
| Cones must have ______ to operate. |
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Definition
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Term
| Rods outnumber cones ___________ |
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Definition
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Term
| Cones are concentrated in __________ vision |
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Definition
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Term
| Rods are concentrated in ___________ vision |
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Definition
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Term
| No photoreceptors can be found on the ___________. |
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Definition
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Term
| The fovea is actually a pit, with the ganglion and bipolar cells pushed to the side, so that ________________ |
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Definition
| the light has an easier time striking the photoreceptors. |
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Term
| Why is it difficult to see color at night? |
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Definition
| because cones need light to operate |
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Term
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Definition
| the conversion of light energy into changes in membrane potentials |
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Term
| The membrane potential of rod outer segments is normally ____________. This is caused by a steady influx of sodium ions. |
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Definition
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Term
| A second messenger ____________ is produced in the cell and its action keeps the channels open. |
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Definition
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Term
| Light reduces cGMP - this causes the sodium channels to __________. This makes the membrane more negative. |
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Definition
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Term
| Photoreceptors __________ in response to light. |
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Definition
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Term
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Definition
| the photopigment in rod outer segments |
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Term
| Prolonged rod illumination caused cGMP levels to fall to a point where no more hyperpolarization is possible. When this situation happens, the rods are said to be |
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Definition
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Term
| ____% of males have some form of color blindness. |
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Definition
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Term
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Definition
| the transition from day to night vision, takes about 20 minutes to fully adjust, time lag is due to the regeneration of rhodopsin |
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Term
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Definition
| the transition from night to day vision, takes about 5 minues to fully adjust |
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Term
| only ________ cells fire action potentials |
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Definition
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Term
| Photoreceptors releases more neurotransmitter in the __________. |
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Definition
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Term
| Photoreceptors ____________ other cells when in darkness. |
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Definition
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Term
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Definition
| an area of the retina that changes the bipolar cell's membrane potential when stimulated by light. |
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Term
| Bipolar cells and ganglion cells have _____________ organization. |
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Definition
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Term
| Center surround organization produces responses that _________ borders |
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Definition
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Term
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Definition
| parvo cells, smaller, 90% of the ganglion cells, sensitive to color |
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Term
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Definition
| magno cells, larger, 5% of all ganglion cells |
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Term
| In the optic chiasm, ganglion cells axons originating from nasal retina cross to the ___________ side. |
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Definition
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Term
| What happens when you cut an optic nerve? |
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Definition
| you lose the ipsilateral monocular crescent |
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Term
| What happens when you cut an optic tract? |
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Definition
| you lost the contralateral hemifield |
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Term
| What happens when you transect the optic chiasm? |
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Definition
| both monocular crescents are lost, tunnel vision |
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Term
| Where does the optic tract go? |
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Definition
| 90% terminate in the LGN, 10% branch off to the midbrain, a very small number go to the hypothalamus |
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Term
| How many layers are in the LGN? |
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Definition
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Term
| Layers 1,4, and 6 receive input form the _______________ eye. |
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Definition
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Term
| The ________ two layers (1 and 2) are magnocellular - receives input from M-cells. |
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Definition
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Term
| The ____________ four layers (3-6) receive parvocellular, receive input from P-cells. |
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Definition
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Term
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Definition
| send their axons to the primary visual cortex |
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Term
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Definition
| a collection of axons coursing from the lateral geniculate nucleus to the visual cortex |
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Term
| The majority of synapses formed in the LGN are not from retinal axons, they are from axons coming back down from _____. |
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Definition
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Term
| ____ is the first place where cells receive signals from both eyes. |
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Definition
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Term
| All neocortex including V1 contains __________ layers. |
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Definition
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Term
| Axons from LGN neurons terminate in _____________. |
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Definition
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Term
| Why is the V1 also known as the striate layer? |
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Definition
| because of the thick black band in layer 4C. |
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Term
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Definition
| the expression used to describe how the retina is mapped in a given structure |
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Term
| Brain structures such as the ___, ____ and ______ contain maps of the retina. |
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Definition
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Term
| Generally, the fovea is going to be |
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Definition
| magified (overrepresented) |
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Term
| Most pyramidal cells are in |
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Definition
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Definition
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Definition
| midbrain structures (pons, and superior colliculous) |
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Definition
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Term
| Types of neuron responses in V1 |
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Definition
| orientation selectivity and direction selectivity |
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Term
| Where do visual signals go after striate cortex? |
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Definition
| the head dorsally toward area MT or head ventrally toward IT cortex |
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Term
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Definition
| an area of neocortex, on the inferior surface of the temporal love, that is part of the ventral visual processing stream and contains neurons with responses to complex objects, including faces |
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Term
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Definition
| an area of neocortex, at the junction of the parietal and temporal loves, that receives input from primary visual cortex and appears to be specialized for the dtection of stimulus movement, also called V5 |
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Term
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Definition
| an area of neocortex, anterior to striate cortex, that is in the ventral visual processing stream and appears to be impotant for both shape perception and color perception |
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Term
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Definition
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Term
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Definition
| failure to recognize faces |
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Term
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Definition
| variations in air pressure |
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Term
| What is the speed of sound |
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Definition
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Term
| What are the vaiables in sound? |
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Definition
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Term
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Definition
| the number of compressed air patches, measured in Hertz, human range 20-20,000 Hertz |
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Term
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Definition
| the difference in pressure between compressed air patches, loudness |
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Term
| The higher the intensity, the _________ the sound |
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Definition
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Term
| Three major divisions of the auditory system |
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Definition
| outer ear, middle ear and inner ear |
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Term
| Components of the outer ear |
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Definition
| auricle (pinna) and auditory canal |
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Term
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Definition
| tympanic membrane, ossicles |
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Term
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Definition
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Term
| The five fundamental steps for turning sounds into signals |
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Definition
| sound waves move the tympanic membrane, tympanic membrane moves the ossicles, the ossicles move the oval window, the motion of the oval window moves the fluid in the cochlea, the movement of the fluid in the cochlea causes hair cells to respond |
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Term
| The middle ear is an air filled cavity, it contains these three ossicles |
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Definition
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Term
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Definition
| an airway between the middle ear and the pharynx, important in equalizing pressure from middle ear and the outside |
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Term
| The ossicles amplify the force exerted against the |
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Definition
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Term
| The ossicles convert air pressure changes into |
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Definition
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Term
| There are two very small muscles attached to the ossicles |
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Definition
| tensor tympani and stapedius |
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Term
| Contraction of the tensor tympani and stapedius decreases the mechanical force exerted by the ossicles on the oval window. Why? |
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Definition
| it protects the inner ear from loud noises, negates the sound of your own voice |
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Term
| If you unroll the cochlea, it is about ____cm long and _____mm in diameter |
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Definition
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Term
| At the beginning of the tube, there are two windows with membranes: |
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Definition
| the oval window (what the stapes contacts) and the round window |
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Term
| Three chambers of the cochlea |
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Definition
| scala vestibuli,(reissner's membrane) scala media, (basilar membrane) scala tympani |
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Term
| How does sound move through the cochlea? |
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Definition
| oval window - scala vestibuli - through Helicotrema - scala tympani - round window |
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Term
| Base of the basilar membrane |
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Definition
| thin and the membrane is stiff, high frequencies encoded here |
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Term
| apex of the basilar membrane |
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Definition
| the apex is wide and the membrane is less rigid, low frequncies are encoded here |
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Term
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Definition
| lies on the basilar membrane, contains the hair cells |
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Term
| Hair cells have about ___________ stereocilia on their heads |
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Definition
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Term
| The tips of the hairs cells contact the ______________. Movement of the hairs cells against the ______________ changes the activity of the hair cells. |
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Definition
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Term
| Hair cells __________ when the stereocilia bend. |
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Definition
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Term
| How do signals get out of the cochlea? |
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Definition
| hair cells synapse with spiral ganglion cells, the cell bodies of these neurons are located in the spiral ganglion, the axons of these neurons form the auditory portion of the vestibulocochlear nerve. |
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Term
| destruction of auditory cortex on one side results in |
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Definition
| the ability to localize sound |
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Term
| Most hearing loss is due to the death or destruction of |
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Definition
| hair cells, these do not generate |
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Term
| Two structures of the vestibular labyrinth |
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Definition
| otolith organs (detect gravity forces and head tilt) and semicircular canals (detect head rotation) |
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Term
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Definition
| saccule and utricle, detect changes in head angle and linear acceleration |
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Term
| The hair cells of semicircular canals are located in the _____ - the bulge at the end of each canal |
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Definition
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Term
| Where do vestibular signals go? |
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Definition
| Hair cells of the vestibular organs synapse with neurons that have their cell bodies in Scarpa's ganglion. Axons from the ganglion form the vestibular portion of the vestibulocochlear nerve. This nerve then goes to the vestibular nucleus in the brain stem. |
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Term
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Definition
| a series of linkages between your vestibular system and the three nerves that control eye movements. The purpose of the relex is to keep you looking in the same place, despite what your body may be doing. |
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