Light Particles Rays( Light, Particles, Rays ): waves of electromagnetic radiation.
Light Particles Rays( Light, Particles, Rays ): travels in straight lines at a constant, very high speed
Light Particles Rays( Light, Particles, Rays ): discrete packets or 'quanta'.
❌: transparent window into the eyeball. ❌: dark, circular opening at the centre of the iris, where light enters the eye ❌: enables changing focus using ciliary muscles ❌: 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. ❌: squishy bits
Transduction occurs when:
Light enters the pupil
Light hits the retina
The retina sends the image to the Optic Nerve
The lens is in focus
Recombining rays from various directions to form a single point on the imaging surface is known as:
Focusing
Refracting
Accommodation
Transduction
Focusing is the job of the:
Cornea
Pupil
Lens
Retina
The cornea lens( cornea, lens ) refracts light at a constant amount.
The cornea lens( cornea, lens ) refracts light by a variable amount.
❌: normal refractive condition ❌: short-sightedness ❌: long-sightedness ❌: inability to change accommodation ❌: different focal lengths for different orientations
Which of the following is true for myopia:
Focal length is too short
Light is focused behind the retina
Need concave corrective lenses
Occurs with old age
Rods: high low( high, low ) sensitivity; daytime night vision( daytime, night vision )
Cones: high low( high, low ) sensitivity; daytime night vision( daytime, night vision )
❌ & ❌ pass electrical impulses to ❌ cells (via ❌/❌/❌ cells). Ganglion cells have long ❌ that exit the eyeball via a bundle called the ❌. Where the optic nerve leaves the eye, there are no ❌ - this is the blind spot.
There are many photoreceptors in the optic disk.
Receptive fields for foveal vision are:
Smaller
Larger
Densely packed
Sparsely packed
Retinal ganglion cell axons terminate in the
Lateral Genicular Nucleus
Optic Nerve
Vitreous Humour
Occipital Lobe
Properties of OFF Centre cells:
Light on the inner portion causes a decrease in ganglion cell activity
Tell us how bright an area is
Help detect local luminance decrements
Cancel out the effect of ON Centre cells
Having both OFF and ON Centre cells makes it more difficult to go below the spontaneous firing rate.
Layers ❌, ❌, and ❌ are from the contralateral eye.
Layers ❌, ❌, and ❌ are from the ipsilateral eye.
Magnocellular Cells: ❌ RFs, ❌ response, ❌ sensitivity, process ❌
Parvocellular Cells: ❌ RFs, ❌ response, ❌ sensitivity, process ❌
The majority of the focusing power in the eyes comes from the lens
High pressure of the aqueous humour can cause:
Glaucoma
Retinal damage
Blindness
Myopia
When our pupils constrict, our depth of focus increases decreases( increases, decreases ).
Amacrine Horizontal( Amacrine, Horizontal ) Cells: receptors synapse with bipolar cells Amacrine Horizontal( Amacrine, Horizontal ) Cells: bipolar cells synapse with ganglion cells
When only rods are active, vision is ❌; when rods cannot function, vision is ❌; when both rods and cones are active, vision is ❌.
Axons from the nasal temporal( nasal, temporal ) side of the retina don't crossover at the optic chiasm.
How many layers does each LGN have?
6 - 2 magnocellular & 4 parvocellular
4 - 2 magnocellular & 2 parvocellular
6 - 4 magnocellular & 2 parvocelluolar
4 - 2 contralateral and 2 ipsilateral in each
OFF Centre cells are sombrero shaped
Ganglion Cells:
Only signal the 'edges' in patters
Respond to absolute rates of intensity
Nothing changes when the overall level of illumination goes up or down
Have antagonistic receptive fields
The surrounding area does the same job as the centre of the cell
