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perception nuke > from lgn to cortex > Flashcards

from lgn to cortex Flashcards

1
Q

Axons of ganglion cell

A

Very long
Make contact with a subcortical structure on their side or cross over

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2
Q

Vice versa representation

A

Left visual field represented in right LGN and vice versa

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3
Q

Contralateral projection

A

Nasal area

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4
Q

Ipsilateral projection

A

Away from nose
Same side of the brain

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5
Q

Retinotopic maps

A

Neighbouring relations that exist in the retina exist in the LGN
Next door neighbour neurons stay neighbours in the LGN

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6
Q

LGN

A

Lateral geniculate nucleus

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7
Q

Monocular cells in LGN

A

Each layer gets input from only one eye
Form a retinotopic map of half a visual field

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8
Q

Layers 1 and 2

A

Large cell bodies
Magnocellular layers
Receive input from M ganglion cells - rods
High contrast sensitivity and low spatial resolution
Process coarse features and motion
Coarse feature is what you can see when you squint

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9
Q

Layers 3 to 6

A

Small cell bodies
Parvocellular layers
Receive input from P ganglion cells - cones
Low contrast sensitivity and high spatial resolution
Process fine features and colour
Fine details are seeing leaves on trees etc

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10
Q

Koniocellular cells

A

Between layers
Receive input from S-cones

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11
Q

Function of LGN

A

Richly connected to many other parts of the brain
Locus at which retinal information can be modulated by brain areas
Part of the brain where retinal informational processing can be modulated by information processing that happens in other parts of the brain

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12
Q

V1

A

Organised in a retinotopic map - spatial neighbouring relations are maintained
First stage of information processing where we combine info from both eyes
Map is distorted due to cortical magnification

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13
Q

Cortical magnification in V1

A

Much more space in the cortex so more neurons dedicated to processing some parts of the stimulus than others

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14
Q

Consequences of cortical magnification

A

More neurons the closer in to the visual field you go
Trade off between having a large visual field and some areas of high acuity
If we had same acuity that we have in the fovea across the whole visual field we would need a fucking huge brain.

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15
Q

Importance of eye movements

A

Move your eyes around to get the high resolution part of the visual system
Visual system patches up all the experiences in order to create a full picture of our visual field

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16
Q

Centre surround receptive field responds best to…

A

Spots of light

17
Q

Neurons in V1

A

Elongated receptive field
Respond best to lines, bars and edges

18
Q

Simple cell structure will connect to…

A

A large amount will connect to one V1 simple cell

19
Q

One simple cell hit with light…

A

V1 cell may not respond

20
Q

Beam of light across simple cells…

A

V1 will really strongly respond to light being beamed across the middle of the receptive fields

21
Q

Simple Cell Receptive Fields

A

Similar to concentric receptive fields, with on centre and off centre
A lot more diversity, but they all have in common that they respond to longer bars of light
They respond to different orientations - orientation tuning

22
Q

Orientation tuning

A

Will respond best when they fire to the orientation they are tuned to
Maximum response from the neuron when it is completely aligned with the faciliatory fields

23
Q

Feature detectors and population codes

A

Neurons not only respond to orientation, but also to intensity of the stimulus
A weak optimal orientation stimulus will fire the same as a slightly slanted bright stimulus

24
Q

Activity in context

A

Have to consider activity of all neurons in context to overcome the ambiguity of what kind of stimulus it is
Brain looks not just at one neuron but at relative activity of neurons that are attuned to different values of the same parameters

25
Q

Complex cells

A

Complex cells would respond to certain orientations independently of where you present that orientation within the receptive field of that cell
Doesn’t matter where the orientation is, it will respond
If you shine light over the whole field, complex cells wont change their response rates

26
Q

Hypercomplex cells

A

Hypercomplex cells are similar to complex cells in that they don’t have clearly defined inhibitory and facilitative regions
But if you extend the bar of light beyond the receptive field, that would reduce the firing rate - endstopping

perception nuke (14 decks)

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