Term
| Visual acuity can be due to both ___ factors and ___ factors |
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Definition
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Term
| There are 6 types of neurons in retina: These include... |
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Definition
2 photoreceptors: Rods and cones
Horizontal cells
Bipolar cells (2nd order neurons)
Amacrine cells
Ganglion cells (send of message to higher centers)
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Term
| The retinal through pathway is made up of... |
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Definition
| Photoreceptors-Bipolar cells- Ganglion cells |
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Term
| The lateral pathway is made up of two of the 6 neurons in the retina known as the horizontal and the amacrine cells. The ... retina is modulated by horizontal cells and the ... retina is modulated by amacrine cells. |
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Definition
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Term
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Definition
* 20/1 outnumber cones (100million to 5 million)
* Very sensitive
* No colour
* Absent from fovea |
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Term
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Definition
* Day vision
* Less sensitive
* 3 types
* allows colour vision
*Descent in fovea |
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Term
| Photoreceptors respond to light by ...polarising. There is no cell in the retina that fires and AP other than the ... cell. Photoreceptors communicate via relative ....... , not ... |
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Definition
| hyper, ganglion, neurotransmitter release, AP's |
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Term
| There are ... types of bipolar cells for cones and ... types of bipolar cells for rods. |
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Definition
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Term
| Horizonatal cells ...polarise in response to light and use the inhibitory NT .. |
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Definition
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Term
| Amacrine cells ... have an axon. They can either use ... or .. as thier NT. |
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Definition
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Term
| The 3rd order neuron in the retinal pathway is the ... cell. These have axons that project down the optic nerve. These cells release ... and fire AP. There are 4 types of ... cells. On, off, M and P |
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Definition
| Ganglion, glutamate, ganglion, |
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Term
| The are 95-125 million photoreceptors. There is space for only 1 million ganglion cells and axons. This problem is solved by using ... The number of ganglion cells is restricted becasue of 3 reasons... |
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Definition
Parallel pathways .
1. Optic nerve/blind spot is small enough that we don’t notice it
2. No restriction on eye movements
3. Energy demands are manageable
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Term
| The point at which the information is split into 2 functional streams is at the ... synpase. These .. respond 2 either depolarising or hyperpolarising when light falls on the retina. Ganglion cells carry 2 types of info: ... |
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Definition
| Ph-BC's. BC's , M type ganglion cells = Motion and low spacial resolution. P type ganglion cells = Colour and high spacial resolution |
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Term
| The reason we have so many types of cells is because of parallel processing. |
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Definition
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Term
Glutamate is release by all receptors in the direct pathway, that being Ph-BC,GC.
True or false |
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Definition
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Term
| Glutamate binds to an ionotropic receptor and allows and infulx of ... to ... the cells and therefore an ... results. |
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Definition
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Term
| Glutamate also binds to metabotropic receptors that work via 2nd messenger system. The receptor in the retina is a mGluR6 receptor and when glutamate binds this receptor it ... the cell |
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Definition
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Term
Bipolar cells with ionotropic receptors (AMPA or Kainate) are ... by light and are therefore known as ... BC's.
Bipolar cells with metabotrobic receptors (mGluR6) are ... by light and therefore known as ... BC's. |
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Definition
hyperpolarised, OFF.
Depolarised, ON. |
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Term
The difference between on an off bipolar cells is the types of receptors they use. Ph release glutamate in dark. BC's react by either hyperpolarising or depolarising depending on if they use mGluR6 or ionotropic receptors |
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Definition
Hyperpolarised = off bipolar cells = ionotropic receptors
Depolarised = on bipolar cells = Metabotropic receptors |
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Term
| On BC only synapse with On GC and the same is with Off and off. True or false |
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Definition
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Term
| On ganglion cell depolarises to light. But this view is still 2 simple. There is something called centre surround where depending on where the light is shone it hyperpolarises or depolarises. An On GC with light on the centre will depolarise. |
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Definition
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Term
| The reason we have this centre surround system is to see ... |
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Definition
| edges and contrast. The center-surround receptive field organization allows ganglion cells to transmit information not merely about whether photoreceptor cells are exposed to light, but also about the differences in firing rates of cells in the center and surround. This allows them to transmit information about contrast. |
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Term
Melanoma Associated Retinopathy is when ...
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Definition
| Antibodies are made against ON BC's. she could still see. |
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Term
| The conventional visual pathway is ... |
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Definition
| Retina to optic nerve to Lateral geniculate nucleus to visual cortex. |
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Term
There are several types of retinoganglion cells.
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Definition
M-ganglion cells are large (Magni), Large receptive fields, motion detection, flicker analysis.
P-ganglion cells are small (Parvi), most numerous >75%, visual acuity and colour vision. |
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Term
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Definition
| The lateral geniculate nucleus (LGN) is the primary processing center for visual information received from the retina of the eye. The LGN is found inside the thalamus of the brain, and is thus part of the central nervous system. It is made up of 6 layers and contains 2 types of cells, the M cells (big) that occupy Layers 1 and 2 and the P cells (small) that occupy layer 3-6. |
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Term
| Neurons of the LGN send their axons through the ... , a pathway directly to the ... (or V1), also known as the striate cortex |
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Definition
| optic radiation, primary visual cortex |
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Term
| The input from the LGN to the visual cortex is in layer ... The M-cells terminate in the 4C alpha section of IVC and the P-cells terminate in 4C beta section of IVC. |
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Definition
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Term
The are geniculate and non geniculate targets of the ganglion cells. The geniculate targets the visual pathways but the non geniculate dont and are involved in .... This works via Melanopsin ganglion cells, these are a small population of GC's that contain the visual pigment. Light activation of melanopsin leads to depolarization of ipGCs.
The melanopsin GC's are involved in circadian rhythm and target the ... found just above the optic chiasm. |
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Definition
circadian rhythm and sleep.
Suprachiasmatic nucleus of hypothalamus (SCN).
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Term
| There is a mixing of information of M and P pathways at the layers ... and ... |
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Definition
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Term
Primary visual cortex = ...
extrastriate visual cortical areas = ... |
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Definition
1. striate cortex or V1 or visual cortex
2. V2, V3, V4, and V5. |
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Term
| How was it discovered that the visual cortex is involved in more that what we can just see? |
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Definition
| Circadian rythms in blind people being jetlagged on planes. This means we can see light completely independent of photo receptors (GC's) . |
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Term
M cells from LGN project to Layer IVC
Cell in Layer IVC project to Layer IVB
In Layer IVB:
some cells show orientation selectivity, Some neurons show preference for the direction of motion of the target and this is called...
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Definition
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Term
There are 2 cortial streams of visual processing.
The ... pathway (where?)
The ... pathway (what?) |
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Definition
Dorsal, Ventral
Remember DW = dorsal where? |
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Term
| The middle temporal lobe (MT) is an area specialised for .... These cells are ... |
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Definition
processing object motion, and receives input from V2, V3 and Layer IVB from V1 (primary visual cortex).
Directional selective. |
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Term
| Colour is defined by 3 properties: |
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Definition
| Hue (wavelength), Saturation (purity), brightness (intensity). |
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Term
Ventral stream
Three photoreceptors for colour vision, REd green blue.
Area V4
Receives input from the blob and interblob regions of the primary visual cortex via V2.
Neurons in V4 have large receptive fields that are both orientation selective and colour selective.
Important for perception of shape and colour.
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Definition
| The final path of the V4 area is the IT, the inferior temportal. This is important for visual memory and perception and is very imporatn for perception of faces. The IT is the last path for the Ventral stream. |
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Term
S
UMMARY
* Conventional visual pathway
M & P Ganglion cells carry information about colour, or motion.
Retina-LGN-V1
* Non-geniculate targets of ganglion cells.
Melanopsin ganglion cells
Suprachiasmatic nucleus
Circadian rhythm.
*
Extrastriate cortical regions
Dorsal pathway: where pathway (area MT)
Ventral pathway: Inferior Temporal lobe
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Definition
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