Cortical Area V1 Flashcards

1
Q

Where do ganglion cells terminate

A

LGN of thalamus- primary visual pathway
Superior colliculous- saccades
Pretectum- Pupillary responses
Hypothalamus- circadian control

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2
Q

What is central homonymous defect and where is the lesion at

A

VF defect in central vision OU. Damage to the lesion at tip of occipital lobe

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3
Q

Most of the LGNs input is from

A

Most from V1
RGC 80% parvocellular, 20% magnocellular.

Activation of V1 neurons depends completely on LGN input, but v1 receives many other cortical and subcortical inputs.

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4
Q

6 layers of the LGN

A

1- contra lateral. Magnocelllular. On and off.
2- ipsilateral. Magnocellular. On and off.
3- ipsilateral. Parvo. Off.
4- Contralateral. Parvo. Off
5- ipsilateral. Parvo. On.
6- contra lateral. Parvo. On.

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5
Q

Retinotopic Mapping. What portion of the VF does each correspond to?

Posterior LGN
Anterior LGN
Lateral/inf LGN
Medial/Superior LGN

A

Central visual field
peripheral visual field
superior VF
Inferior VF

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6
Q

Ratio of Relay to interneurons

A

Relay: Interneurons 4:1

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7
Q

Relay cells receive input from where?
-what NT does it use
Interneurons do what?
-What NT does it use?

A

Relay: receive input from sources outside the LGN. Including magnocellular, parvocellular, and koniocellular. Uses glutamate. Excitatory.

Interneurons help with input/output within the LGN.
GABA. Inhibitory.

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8
Q

Central sulcus separates what portions of the brain

A

Frontal and parietal

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9
Q

Sylvian/lateral fissure separates what portions of the brain

A

temporal from frontal and parietal

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10
Q

Transverse fissure separates what portions of the brain

A

Cerebellum from occipital lobe

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11
Q

Why is V1 called the striate cortex?

A

Has a stripe of myelin down the center called the line of gennari. Projects into layer 4B from 4C alpha

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12
Q

First site along primary visual pathway that has binocular neurons- they can respond to either eye or both

A

V1

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13
Q

Cortical mag

A

mm of cortex/deg of VF

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14
Q

Inverse cortical mag

A

deg of VF/mm of cortex.

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15
Q

Layers of V1

A

Layer 1: Supergranular. Synapses are sending info to each other.

Layer 2,3,4A,4B: Supragranular. Send excitatory output to other cortical areas. Koniocellular cells send axons to blob cells in layer 3.

Layer 4C: Granular layer. LGN sends input here from M and P cells. Within this layer, signals from the R and L eye are separated. Monocular.
(parvo–> 4C beta. Magno–> 4C alpha)

Layer 5, 6: Infragranular. Send output to cortical and subcortical areas.

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16
Q

Ways to classify visual cortex cells.

A

Anatomical:
Spiny- excitatory. Glutamate.
Smooth- Inhibitory. Gaba.

Functional classifications:
Simple
Complex
End stopped

17
Q

Simple cells of V1

A

Little or no spontaneous activity.
Edge detects (-+-) or line detectors (-+)
Spatially linear elongated receptive fields. Not center surround.
Either mono or bino
Show spatial frequency (size) specification

18
Q

Complex cells of V1

A
Spatially non linear 
High spontaneous activity 
More numerous than simple cells 
Strong orientation specificity (tuning) 
May show true direction of motion
Most binocular
19
Q

End stopped cells of V1

A

If the stimulus gets beyond a certain length, the cell does not increase its response.

20
Q

What is the simple cell receptive field made up of? What is the complex cell receptive field made up of?

A

Simple cell receptive field made of LGN input.

Complex cell receptive field made from simple cell input.

21
Q

Huber and Wiesel classification of binocularity

A

1 can only respond to info from the contralateral eye.
2-3 respond stronger to the contralateral eye but can respond to ipsi.
4 equally responds to ipsi and contralateral.
5-6 respond to ipsilateral stronger but can respond to the contralateral one.
7 can only respond to ipsi