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Neuroendocrine Test Three > Visual Physiology Dr. Pierce > Flashcards

Visual Physiology Dr. Pierce Flashcards

1
Q

How are the three main cells connected in vision

A

Photoreceptors connect to bipolar cells which connect to ganglion cells which connect to the brain

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2
Q

What photoreceptor has many cells and many bipolar cells connected to one ganglion cell? What is the benefit?

A

Rods Sacrifice acuity to gain sensitivity allowing rods to operate in dim light

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3
Q

What photoreceptor has less convergence and sends info to only one bipolar cells that goes to only one ganglion cell? What’s the benefit?

A

Cones Maximizes acuity

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4
Q

Where do the density of rods and cones peak?

A

Rod density is greatest about 20 degrees from fovea and cones peak at the fovea

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5
Q

Explain what happens to photoreceptors in the dark.

A
  • Photoreceptors Depolarize in the Dark creating a graded potential
  • Glu is released
  • Binds MgluR6 acting inhibitory on bipolar cells
  • Bipolar cell does not depolarize so no impulse is sent to the brain

(Glutamate release from rods/cones is highest in dark and not stimuluated by photons)

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6
Q

What happens to photoreceptors in the light?

A
  • They hyperpolarize and do not create graded potentials
  • No glutamate is released
  • Bipolar cells spontaneously depolarizes releasing Glu on Ganglion cells
  • Ganglion cell generates an AP
  • Send signal to brain

(Glutamate release from rods/cones is low in light )

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7
Q

What are the direct targets of the retina? Describe 3 of them

A
  • LGN:
    • Major target, regulates flow of info to primary VC
  • Superior colliculus:
    • Connects tectospinal tract sends info to ant. horn cells
    • makes map of visual space to make correct motor responses to move eyes
  • Pretectum:
    • Pupillary light reflex- sends projections to edinger westphal then ciliary ganglion
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8
Q

What are two more of the direct targets of the retina? (Continuation of another card)

A
  • Hypothalamus:
    • visual imput to drive light dark circadian rhythm and endocrine fxns
  • Accessory optic nuclei:
    • Adv. visual processing
    • optokinetic nystagmus in response to prolonged large field motion
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9
Q

What is the fxn of LGN

A
  • Control motion of eyes and converge on point of interest
  • Control focus of eyes based on distance
  • Determine relative postiion of objects to map them
  • Detet movement relative to object
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10
Q

V1 function

A

Edges and contours of objects

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11
Q

V2 function

A

Depth perception

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12
Q

V3a fxn

A

Identify if motion is occuring, yes or no

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13
Q

V4 fxn

A

Complete processing of color inputs

  • lesions can cause achromatopsia
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14
Q

MT/V5 fxn

A

Tracks motion across a scene with directionality by responding to moving edges

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15
Q

What are occular dominance columns? What are Orientation columns? What are blobs?

A
  • Columns in the visual cortex that respond to one eye or the other. They span all six layers. Truly look like stripes. Prominent in V1.
  • Respond to different orientations, each column responds to visual line stimuli of different angles. Spans all 6 layers. Truly look like swirls
  • Neurons that are sensitive to color and assemble into cylindrical shapes. All layers. Polka dots, cytochrome oxidase stain shows
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16
Q

What is the importance of Melanopsin Ganglion cells?

A
  • Detect blue light without forming an image
  • Goes directly to the suprachiasmatic nuclei of the hypothalamus which impacts pineal gland production of melatonin
17
Q

Describe the dorsal pathway of vision.

A
  • This is the “Where” path. Information comes from primary visual cortex and travels to parietal/frontal cotex to associate vision with movement
  • V1
  • V2,3
  • V5/MT
  • Parietal lobe
18
Q

Where does information in the dorsal pathway travel specifically?

A
  • V1
  • V2,3
  • V5/MT
  • Parietal lobe

Complete motor acts based on vision

19
Q

What is the ventral pathway?

A
  • “What” path that involves figuring out what you are looking at, so interpretation of images.
  • From primalry visual cortex to the inferior temporal cortex
  • Recognizing or copying shapes, forms and faces and complex patterns are part of this pathway
    • you can damage one area and not the others
20
Q

What is the specific path of information in the ventral path?

A
  • V1
  • V2
  • V4
  • Temporal lobe

Neuroendocrine Test Three (19 decks)

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