Introducing the eye (Introduction)
by David Turell 
, Friday, April 02, 2021, 15:16 (1114 days ago)
Its complexity is equal only to our brain:
https://uncommondescent.com/evolution/from-philip-cunningham-the-human-eye-like-the-hum...
"The human eye consists of over two million working parts making it second only to the brain in complexity.
"The retina covers less than a square inch, and contains 137 million light-sensitive receptor cells. The retina possesses 7 million cones, which provide color information and sharpness of images, and 120 million rods which are extremely sensitive detectors of white light.
"There are between seven to ten-million shades of color the human eye can detect.
"The rod can detect a single photon. Any man-made detector would need to be cooled and isolated from noise to behave the same way.
***
"The eye is so sensitive that it can, under normal circumstances, detect a candle 1.6 miles away,
"But if you’re sitting on a mountain top on a clear, moonless night you can see a match struck 50 miles away.
"It only takes a few trillionths of a second, (picoseconds), for the retina to absorb a photon in the visible range of the spectrum.
"The inverted retina, far from being badly designed, is a design feature, not a design constraint. Müller cells in the ‘backwards’ retina span the thickness of the retina and act as living fiber optic cables to shepherd photons through to separate receivers, much like coins through a change sorting machine.
"The eye is infinitely more complex than any man-made camera.
"The eye can handle between 500,000 and 1.5 million messages simultaneously, and gathers 80% of all the knowledge absorbed by the brain.
"The brain receives millions of simultaneous reports from the eyes. When its designated wavelength of light is present, each rod or cone triggers an electrical response to the brain, which then absorbs a composite set of yes-or-no messages from all the rods and cones.
"There is a biological computer in the retina which compresses, and enhances the edges, of the information from all those millions of light sensitive cells before sending it to the visual cortex where the complex stream of information is then decompressed.
"This data compression process has been referred to as “the best compression algorithm around,”.
***
"In an average day, the eye moves about 100,000 times, and our mind seems to prepare for our eye movements before they occur.
"In terms of strength and endurance, eyes muscles are simply amazing. You’d have to walk 50 miles to give your legs the same workout as the muscles in one of your eyes get in a day.
"The brain exploits a feedback system which produces phenomenally precise eye movements.
"The human is the only species known to shed tears when they are sad.
"Tears are not just saline. Tears have a similar structure to saliva and contain enzymes, lipids, metabolites and electrolytes.
"And, tears contain a potent microbe-killer (lysozyme) which guards the eyes against bacterial infection.
"The average eye blinks one to two times each minute for infants and ten times faster for adults.
"This blinking adds up to nearly 500 million blinks over an average lifetime."
Comment: No need to comment on the need for a designer. Not by chance development from ancient eye sports
Introducing the eye
by David Turell , Monday, January 03, 2022, 22:50 (837 days ago) @ David Turell
Seeing faint light:
https://www.sciencedaily.com/releases/2022/01/220103121742.htm
"PSI scientists have shed light on an important component of the eye: a protein in the rod cells of the retina which helps us see in dim light. Acting as an ion channel in the cell membrane, the protein is responsible for relaying the optical signal from the eye to the brain.
***
"'It's thanks to the rod cells in our eye that we can observe the stars in the night sky," explains Jacopo Marino, a biologist with PSI's Laboratory of Biomolecular Research. "These photo cells are so sensitive to light that they can detect even a single photon reaching us from a very remote part of the universe -- a truly incredible feat." The ability of our brain to eventually translate these light beams into a visual impression is partly down to the cyclic nucleotide-gated (CNG) ion channels whose three-dimensional structure has now been illuminated by a PSI research group led by Jacopo Marino.
"The ion channel acts as a gatekeeper controlling whether specific particles are allowed through to the interior of the receptor cell. It is embedded in the protein-rich shell -- the cell membrane -- of the rod cells. In darkness, the ion channel, and thus the gate to the cell, is completely open. But when light hits the eye, it triggers a cascade of processes in the rod cells. This ultimately causes the gate to close, with the result that positively charged particles, such as calcium ions, can no longer enter into the cell.
"This electrochemical signal continues via the nerve cells into the brain's visual cortex, where a visual impression -- such as a flash of light -- is created.
***
"The protein comprises four parts: three lots of subunit A, and one lot of subunit B. A correctly functioning ion channel is only possible in this combination. In their study, PSI scientists show why the B subunit seems to play such an important role: a side arm of the protein -- a single amino acid -- protrudes from the rest of the protein, like a barrier across a gateway. This narrows the passage in the channel to the point where no ions can pass through.
"'No one expected that -- it came as a total surprise," says Diane Barret. Other narrow places already exist in the A subunit -- like main gateways -- which were previously thought to be the only ones. It is interesting to note that the additional barrier is found not only in the protein from the cow's eye, but seems to apply to all types of animal, as the scientists showed. Whether crocodiles, eagles or humans -- all living creatures with an ion channel in their eye have the same protruding amino acid at this position in the protein. As it has been preserved so consistently during evolution, it must be essential for the functioning of the channel."
Comment: The fact that it is conserved shows the detail of design in stepwise fashion by God. It seems the disparaged backward human retina by Darwinists has received perfect results in design from past stages.
Introducing the eye: a study of retina cells
by David Turell , Sunday, April 09, 2023, 16:20 (377 days ago) @ David Turell
Not exactly like a camera:
https://medicalxpress.com/news/2023-04-functional-cells-retina-natural-panoramic.html
"Existing neuroscientific models of the visual system suggest that it represents the visual world just as a camera would, encoding the positions of different objects similarly. An animal's surrounding environment, however, constantly changes, and these changes could also influence the processing of visual information.
"Researchers at the Institute of Science and Technology in Austria and LMU in Germany recently gathered evidence supporting this hypothesis and showing that the organization of neurons in the mouse retina is affected by panoramic (i.e., wide view) visual statistics, such as non-uniformities in light levels.
***
"To examine the organization of sensory space that activate each neuron in the mouse retina (receptive fields) in relation to the scenes that mice are observing, Jösch and his colleagues developed a new optical imaging technique. This technique allows them to measure and track the activity of thousands of neurons in a single retina simultaneously.
***
"The researchers conducted their experiments on extracted mice retinas. Like that of most mammals, the mouse retina does not include the small area known as the fovea, a small slump in the retina that allows humans and other primates to see at high definition. The fovea, which makes up less than 1% of the entire human retina, is known to play a key role in the visual perceptions of which humans are more conscious. The remaining 99% of the human retina also contributes to visual perceptions, from which many appear to be unconscious processes. Thus, from a human centric perspective, this study focuses on the processing happening the latter 99%.
"Jösch and his colleagues found that the computations performed by neurons in the mice retina changed depending on the panoramic visual statistics of what that part of the retina usually sees during daylight. This supports their initial hypothesis that the visual system is not inherently homogenous and is in fact adapted to the external environment.
"'To our surprise, we found that retinal neurons are more likely to inform the rest of the brain when a stimuli change is unexpected," Jösch said. "Importantly, the unexpected depends on where the neuron looks, either the sky or the ground. Thus, retina circuits systematically adapted their properties from the lower to the higher visual field to represent the world more efficiently."
"Overall, the findings gathered by this team of researchers suggest that the panoramic structure of natural scenes affects the organization of different processing strategies in different regions of the retina. This expands previous models of the visual system, highlighting its adaptive and dynamic nature.
"'We usually assume that the visual system is homogenous, or in other words, that the visual world is represented like a camera, measuring each position similarly," Jösch added. "However, our natural surroundings are not similar; they systematically change from ground to sky. Thus, a system that evolved to live in nature should consider this. Our results indicate that living organisms' visual system has adapted to cope with natural constraints to improve the efficiency of their neuronal code.'"
Comment: such complex organization requires design in my view. Our eyes don't mimic cameras, they mimic our eyes.