👀 Vision

Vision

What is bottom-up processing?

Works by building meaning from raw sensory data

What is top-down processing?

Driven by our prior knowledge

Light is a form of…

Electromagnetic radiation

What are the waves in radiation called?

Photons

What is wavelength?

Determines the colour we see

What is amplitude?

Determines how bright it appears

What is the electromagnetic spectrum for humans?

400 and 700 nanometers

Light can be…

Refracted

Where does the eye sit?

Orbit of the skull

What cushions the eye?

Fat

What is the purpose of blinking tears?

Helps to keep the surface clean

What type of neurons does the retina contain?

Interneurons

What receptors does the retina contain?

Photoreceptors

What is one structure that processes incoming light?

Sclera, cornea, anterior chamber, pupil, lens, vitreous chamber, and retina

Where can visual interneurons and photoreceptors be found?

The retina

What is the purpose of interneurons and photoreceptors?

For detecting and processing incoming light

What is the retina made up of?

The optic disk, the macula and the fovea

What type of vision does the retina support?

Central vision

What is central vision?

Allows us to see fine detail, and peripheral vision

What is found underneath the optic disk, macula and the fovea?

The pigmented epithelium

How many layers are in the retina?

5

What is the outermost layer of the retina?

The ganglion cell layerWhat

is the purpose of the ganglion cell layer?

Ganglion cells

What is the inner plexiform layer?

Ganglion cells form connections with amacrine and bipolar cells

What cells does the inner nuclear layer contain?

Bipolar, amacrine, and horizontal cells

Where does bipolar cells connect with horizontal cells and photoreceptors?

The outer plexiform layer

What are the layers of the retina?

Outermost layer

Inner plexiform layer

Inner nuclear layer

Outer plexiform layer

Outer nuclear layer

What are the two types of photoreceptors?

Rods and cones

Are rods suitable in high-light or low-light conditions?

Low-light conditions

What are rods responsible for?

Scotopic vision

What are cones responsible for?

Photopic vision

Where are cones found?

In the fovea

Where are rods found?

In the peripheral retina

Cones are sensitive to…

Colour

What are photoreceptors responsible for?

Transducing light energy into electrical signals

What is the name of the molecule responsible for transducing light into electrical signals?

Rhodopsin

What are the two components of rhodopsin?

Opsin and retinal

What vitamin is responsible for retintal?

Vitamin A

Opsin is a…

Large protein chain

Retinal is sensitive to…

Light

What is the process of the retina absorbing light?

Isomerisation

Photoreceptors produce ________ rather than action potentials

Graded potentials

What is the resting potential for photoreceptors?

-30mV

What maintains the resting potential of photoreceptors?

Cyclic guanosine monophosphate (cGMP)

Does cGMP open or close sodium channels?

Open

What are horizontal cells?

Integrates information from neighbouring photoreceptors

What are the two types of bipolar cells?

Diffuse bipolar cells & midget bipolar cells

What is the role of bipolar cells?

Respond to light falling within their receptive field

Where are diffuse bipolar cells located?

The peripheral retina

Where are midget bipolar cells located?

The fovea

Ganglion cells receive input from _______ cells and ________ cells

Bipolar and amacrine

What are the three types of ganglion cells?

M cells, P cells and K cells

Visual information leaves the eye via the ________

Optic nerve

What is the optic chiasm?

When the two optic nerves partially cross at a point

Which part of the brain contains LGN?

The thalamus

What does LGN stand for?

Lateral geniculate nucleus

What is another name for the striate cortex?

The primary visual cortex

What is the striate cortex responsible for?

The initial cortical processing of visual information

What is cortical mapping?

Correlating the location of neural activity with the position of an object in the visual field

What are simple cortical cells?

Respond to lines and adges of a specific orientation in a fixed location

What are complex cortical cells?

Similar to simple cortex cells but are less dependent on the exact position of the stimulus within their receptive field

What are end-stopped cells?

Respond best to lines or edges of a specific length

What are the types of cues associated with vision?

Monocular and binocular cues

What are monocular cues?

Cues that can be detected with one eye

What are binocular cues?

Cues that can be detected with both eyes

________ theory proposes that colour perception arises from the combines output of three types of cone photoreceptors

Trichromatic

What is colour contrast?

Refers to the way in which the same colour can appear quite different depending on the surrounding colours

What is colour constancy?

The ability to perceive the colours colours of objects as remaining stable even when the type of light illuminating them changes