Week 5

[blank_start]Light[blank_end]: waves of electromagnetic radiation. [blank_start]Rays[blank_end]: travels in straight lines at a constant, very high speed [blank_start]Particles[blank_end]: discrete packets or 'quanta'.

[blank_start]Cornea[blank_end]: transparent window into the eyeball. [blank_start]Pupil[blank_end]: dark, circular opening at the centre of the iris, where light enters the eye [blank_start]Lens[blank_end]: enables changing focus using ciliary muscles [blank_start]Retina[blank_end]: light-sensitive membrane in the back of the eye that contains rods and cones, which receive an image from the lens and send it back to the brain through the Optic Nerve. [blank_start]Aqueous/Vitreous Humour[blank_end]: squishy bits

Transduction occurs when:

Recombining rays from various directions to form a single point on the imaging surface is known as:

Focusing is the job of the:

The [blank_start]cornea[blank_end] refracts light at a constant amount. The [blank_start]lens[blank_end] refracts light by a variable amount.

[blank_start]Emmetropia[blank_end]: normal refractive condition [blank_start]Myopia[blank_end]: short-sightedness [blank_start]Hyperopia/Hypermetropia[blank_end]: long-sightedness [blank_start]Presbyopia[blank_end]: inability to change accommodation [blank_start]Astigmatism[blank_end]: different focal lengths for different orientations

Which of the following is true for myopia:

Rods: [blank_start]high[blank_end] sensitivity; [blank_start]night vision[blank_end] Cones: [blank_start]lower[blank_end] sensitivity; [blank_start]daytime[blank_end]

[blank_start]Rods[blank_end] & [blank_start]cones[blank_end] pass electrical impulses to [blank_start]ganglion[blank_end] cells (via [blank_start]bipolar[blank_end]/[blank_start]amacrine[blank_end]/[blank_start]horizontal[blank_end] cells). Ganglion cells have long [blank_start]axons[blank_end] that exit the eyeball via a bundle called the [blank_start]optic nerve[blank_end]. Where the optic nerve leaves the eye, there are no [blank_start]photoreceptors[blank_end] - this is the blind spot.

There are many photoreceptors in the optic disk.

Receptive fields for foveal vision are:

Retinal ganglion cell axons terminate in the

Properties of OFF Centre cells:

Having both OFF and ON Centre cells makes it more difficult to go below the spontaneous firing rate.

Layers [blank_start]1[blank_end], [blank_start]4[blank_end], and [blank_start]6[blank_end] are from the contralateral eye. Layers [blank_start]2[blank_end], [blank_start]3[blank_end], and [blank_start]5[blank_end] are from the ipsilateral eye.

Magnocellular Cells: [blank_start]large[blank_end] RFs, [blank_start]fast[blank_end] response, [blank_start]high[blank_end] sensitivity, process [blank_start]motion[blank_end] Parvocellular Cells: [blank_start]small[blank_end] RFs, [blank_start]low[blank_end] response, [blank_start]low[blank_end] sensitivity, process [blank_start]colour[blank_end]

The majority of the focusing power in the eyes comes from the lens

High pressure of the aqueous humour can cause:

When our pupils constrict, our depth of focus [blank_start]increases[blank_end].

[blank_start]Horizontal[blank_end] Cells: receptors synapse with bipolar cells [blank_start]Amacrine[blank_end] Cells: bipolar cells synapse with ganglion cells

When only rods are active, vision is [blank_start]scotopic[blank_end]; when rods cannot function, vision is [blank_start]photopic[blank_end]; when both rods and cones are active, vision is [blank_start]mesopic[blank_end].

Axons from the [blank_start]temporal[blank_end] side of the retina don't crossover at the optic chiasm.

How many layers does each LGN have?

OFF Centre cells are sombrero shaped

Ganglion Cells: