PSYC2020 Practice Questions - Wk5 Visual System Flashcards
How much visual information goes to the superior colliculus, and not to visual processing?
10%
What are the 3 steps to visual pathway (overview)?
- Image formation - eye
- Transduction - retina
- Visual processing
what is the difference between optic tracts and optic nerves?
Nerves = bilateral visual fields
Tracts = unilateral visual fields
How much of optic nerve fibres cross a the optic chiasm? And what is the effect of this?
50%
information from the nasal hemiretina crosses over to the cortex that process that respective visual field
What’s the difference between optic nerves and optic tracts? And what does this mean for potential damage?
Bilateral vs unilateral information, respectively. So if you cut one you’ll lose either both fields or just one.
What does the term retinotopic mean?
Adjacent points in the visual field map onto adjacent points on the retina. and this mapping maintained through the processing hierarchy
What does cortical magnification refer to?
More cortex is dedicated to processing the central visual field (near the fovea) than the periphery
What is a receptive field?
The regions on the retina which excite or inhibit a cell. So a neuron has an area in space which it will respond to.
What are possible characteristic of Receptive Fields? 4
They can have small or large spatial resolution.
They have both an excitatory and inhibitory region.
What shape are centre surround cells (1) and simple cells (1)? 2
Round and rectangular, respectively.
What are four things that happen in the eye?
- Form an image
- Generate a neural signal through transduction
- Early neural processing !
- Transmit the visual signal to the brain
Where does the visual spectrum of light lie on the whole spectrum?
Between ultraviolet and infrared light
what is the cornea and what does it do?
A transparent outer layer of the eye. It refracts (bends) light
what does the lens do in the eye?
Fine tunes the image. It stiffens with age
What is the accomodation reflex of the eye lens?
Lens shape automatically changes depending on what you are looking at
What do the pupil and iris do?
The opening (pupil) is regulated by contractile tissue (iris). It varies light and thereby focal length.
What is the fovea?
High acuity part of the eye, lots of cones. Where RGCs are cleared away
what is the backward writing problem and how is it solved?
Light has to pass through the processing layers before the receptors, meaning it will pass through all the nerves. The fovea clears away most of the wiring in the center to allow more clarity of light.
Where does the optic nerve go?
To LGN
What is the optic disc?
The blind spot where nerves and blood vessels exit the eye.
What does it mean if each eye has a blind spot but there is no black hole in vision?
Vision is construction
In completion what happens to edges, and what happens to surfaces?
Continued, interpolated respectively
What cells in the eye contribute to lateral communication?
What is lateral communication?
Horizontal and amacrine cells. Early processing
What is photopic vision?
Well lit vision