This week we learned many a thing about visual information processing starting from the structure-function relations of eye all the way to further information processing in the human brain.
One exciting thing that was new to me is the basis of light energy conversion into changes in membrane potential – the process known as phototransduction. Even though process behind light transformation into membrane potential is somewhat different for two different kinds of photoreceptor cells (namely rods and cones), they still have quite a lot in common. Both are initiated when light photon gets absorbed by a photoreceptor. This changes photoreceptors conformation, which leads to a biochemical cascade causing the closing of Na+ channels and thus the cell membrane hyperpolarizes. This causes an action potential, which proceeds down the optic nerve and optic tract all the way to primary visual cortex which situates in the back of the forebrain. One interesting thing about visual information processing in the brain is that the input from right eye is processed in the primary visual cortex of left hemisphere and vice versa.
Considering the complexity of visual information processing machinery in human bodies, no wonder there is so many different kinds of eye-function disorders. While some of the these are already fixable with modern medical technology, there is still no treatment for some others.