Outline: The Retina

Layered structure (from inside, where the light is coming from, to the outside):

Vitreous
Ganglion cell axons heading toward (and then forming) the optic nerve
Ganglion cell bodies
Inner Plexiform Layer (axons/dendrites)
Inner Nuclear Layer (amacrine, bipolar & horizontal cell bodies)
Outer Plexiform Layer (axons/dendrites)
Outer Nuclear Layer (photoreceptors)
Pigment Epithelium (melanin)
Choroid

Pigment Epithilium: Nocturnal/tapetum vs Diurnal/absorption

Passage of light through retina to receptor outer segments

Phototransduction

Rods vs cones
Quantal absorption, Photoisomerization, Cascade
Principle of univariance
Hyperpolarizing effects of light (in, e.g., mammals)

Receptor sampling

More central than eccentric/periphery
None in the blind spot
1º rod-free zone

Specialization

Rods: scotopic levels, sensitive, low spatial resolution, peripheral, slow
Cones: photopic light levels, high spatial resolution, central, color vision, fast
Mesopic light levels with both systems available
Light level range 10² - 10¹⁴ quanta/sec (starlight vs the beach on a sunny day)

Retinal processing

Wiring diagram
Concept of the receptive field (RF)
Lots of graded processing prior to the ganglion cells
Horizontal cells: diffuse, large RFs
Bipolar cells: spatially antagonistice RFs
Amacrine cells: On and off types, transient, graded responses
Ganglion cells: COMING UP SOON!!!