Week Six Flashcards

1
Q

Function of eye lenses

A

Lenses in our eyes invert the image and project is back onto the photoreceptors.

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2
Q

Retinal Ganglions

A
  • In order to see objects/ lines/ shapes etc. we have a system for enhancing edges.
  • Ganglion cells in the retina have a receptive field. Some of these cells can be excited by light inside the receptive field or inhibited by light outside the receptive field.
  • Retinal ganglions cells can act as edge detectors. They an integrate patterns of light over an area and indicate whether that pattern is different to that in an adjacent area.
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3
Q

What is the Fovea

A
  • The exact centre of the visual field.
  • Represents the location they eye is pointing when you look at something.
  • The fovea has the greatest concentration of photoreceptors.
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4
Q

Photoreceptors

A

Split into two categories

  • cones
  • rods
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5
Q

cones

A
  • Cones are for coloured vision
    ○ They can see very fine detail as they are densely packed with fovea.
    Work primarily in bright light.
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6
Q

rods

A
- Rods are black and white vision 
	○ Mostly widely spaced throughout the retina
	○ More in the peripheral visual field 
	○ Low acuity 
Work well at night
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7
Q

Process of Seeing

A
  • Left side of the visual field of each eye projects to the right side of the brain and vice versa.
  • Nerve cells cross over at the optic chiasm
  • Travel to lateral geniculate nucleus of thalamus (LGN) then back to occipital cortex at the back of the brain
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8
Q

Primary Visual Cortex Cell Division

A
  • Simple cells
    * Respond to an edge at a particular orientation in a specific part of the visual field
    • Complex cells
      • Respond to an edge at a particular orientation but falling anywhere within a wider field. May also repond to direction of motion
    • Hypercomplex cells
      • Respond to a line which ends within the receptive field (‘end-stopping’)
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9
Q

agnosia

A
  • Inability to recognise objects

* Prosopagnosia – specific inability to recognise faces

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10
Q

temporal lobe and vision

A

• Temporal lobe – detectors for combinations of lines/eges (squares or cone shapes)

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11
Q

parietal lobe and vision

A

damage to parietal lobe causes problems of spatial awarenesss

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12
Q

visual maps

A
  • At all levels of the visual system, information is distributed in multiple parallel visual maps
  • Retinotopic – mimics the layout of the visual field
  • Often center-weighted (central 5 degrees represented most strongly)
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13
Q

stabalisation of visions

A
  • Other connections exist with higher cortical levels, including frontal association cortex
    • Tell you where your eyes are pointing to make an internal map of where things are located
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14
Q

blindsight

A

• Unconscious, but not conscious, awareness of a visual stimulus
May be observed in some cases of visual neglect

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