Title: Psychology / Biopsychology / 11_VisualSystem
Tags: Biopsychology::11_VisualSystem Biopsychology::Semester_2

Q: What part of the eye is also part of the nervous system?
A: The retina.

Q: In what two parts is the retina split?
A: nasal Retina
temporal Retina

Q: What is the fovea?
A: The part of the eye that processes our central vision information, aka the space that we focus on. The rest of the retina is responsible for our peripheral vision

Q: Why is there a blind spot in our eye?
A: The part where the optic nerve connects to the retina has no receptors on it.

Q: Why is the nasal side of the retina bigger ?
A: As light is mirrored before it hits the retina, the nasal part being bigger means that the peripheral view gets better coverage (only one eye is covers each side compared to the middle, which is covered by both eyes)

Q: Why are we not confused by the blind spot in our eyes, even when we close one eye?
A: Our brain fills in the visual information by interpolating.

Q: What 5 kind of cells does the retina consist of?
A: Bottom to top:
1. Photoreceptors (translate light to electrical signals)
2. Horizontal cells (interconnect PR and connect)
3. Bipolar cells
4. Amacrin cells (connecting)
5. Ganglia cells (they have long axons that build the optic nerve)

Q: Out of all of the cells in the retina, which are the ones that emit action potential?
A: Only the ganglia cells

Q: Why do the layers of the retina seem inverted?
A: (The photoreceptors are at the bottom)
It is assumed that light going through all of the layers prevents reflections from within the eye from reaching the photoreceptors.

Q: What two types of photoreceptors are there in the eye?
A: Rods and Cones

Q: How do rods and cones process color differently?
A: Cones can differentiate many colors, while rods mostly deal with black/white on gradients

Q: Where in the retina is the lowest concentration of rods found?
A: In the blind spot.

Q: How do rods and cones compare in size?
A: Rods are a lot larger than cones (cones provide a better resolution per space)

Q: How do rods and cones differ in concentration across the retina?
A: In the fovea, we have a very high concentration of cones.
This falls off quickly when going towards the periphery, with more rods being present.
Those also fall off when going even further towards the periphery.

Q: What 3 types of cones do we have on the retina?
A: blue, green, red → for processing mixtures of colors

Q: Why are we bad at seeing colors in the dark?
A: The cones in our retina are less light-sensitive than the rods.

Q: How is the retinal ganglia connected to the visual cortex?
A: Through the Thalamus

Q: What parts of the two eyes map to which hemisphere of the brain?
A: The temporal parts go into the SAME side
The nasal parts go into the OPPOSITE side
→ things in the middle of the visual field arrive in both hemispheres

Q: What is retinotopic organisation?
A: Neighboring parts of the retina are processed in neighbouring parts of the visual cortex (flipped and mirrored)

Q: How are primitive shapes like lines recognized in the visual cortex?
A: In a group of neurons that is responsible for a certain part of the visual field, different "columns" of neurons respond to different orientations of lines → This identifies smaller line segments

Q: How does the visual cortex bind contrasts and lines together into meaningful percepts?
A: "Gamma band response" (visual binding)
Neurons that respond to similar line orientations in different parts of the visual field respond in synchronous rhythmic activity, signalling that a longer line is recognized.

Q: What are the 2 pathways of higher visual processing?
A: dorsal path: orientation in space
ventral path: identification of objects

Q: To which parts of the brain is the retinal ganglia connected?
A: Thalamus: 90% of signals
Colliclus superior: 10% of signals (eye movement control, visual attention → location)

Q: What advantage does visual processing in the colliclus superior bring?
A: Information regarding attention (and location of stimuli) arrives in the parietal cortex faster than the rest of the visual information, which makes the processing in the parietal cortex more efficient

Q: What happens when the V1 is destroyed, but the midbrain stays intact?
A: Blindsight occurs
Participants cannot consciously see anymore, however, locational information is still present in the brain, allowing them to subconsciously act upon this information

Q: How does the brain activity differ for congenitally blind and late blind people when reading braille?
A: Congenitally blind people use the higher visual areas
Late blind people ALSO use the primary visual cortex

Q: If you remove the left thalamus, what will happen to the visual field?
A: You lose sight in the right side of your visual field. (right nasal part and left temporal part)

Q: A stimulus is presented in the left visual field, which brain hemisphere processes it?
A: The right hemisphere.