rod-cells

New function for rods in daylight

Vision – so crucial to human health and well-being – depends on job-sharing by just a few cell types, the rod cells and cone cells, in our retina. Botond Roska and his group have identified a novel function for rod photoreceptor cells in the retina in daylight. Driven by cones and mediated by horizontal cells, rods help to increase contrast information at times when they are not directly sensing light. The retina thus repurposes its cells in different light conditions to increase the amount of visual information about the environment.

(Caption: Horizontal cells in the retina)

Task sharing in the retina seemed clear: Two different kinds of photoreceptor cells take on two different visual tasks. Rods allow us to see at night, cones operate during the day and enable color vision. However, the question as to why there are about 20 times more rods than cones in a human retina, when daytime vision is much more relevant for us, has usually led to a shrug of shoulders. It seemed a waste of resources.

Botond Roska and his group at the Friedrich Miescher Institute for Biomedical Research, could now show in a study published recently in Nature Neuroscience that the rods in mouse take on an important function during daytime vision as well.

The scientists showed that in bright light, the rods mediate a so called surround inhibition. Surround inhibition is an important feature in the retina because it allows not only to transmit information about whether a photoreceptor is exposed to light, but also about contrast. While the cone cells hyperpolarize in bright light and thus send a visual signal to the inner retina, the rods depolarize, inversely matching the activity pattern of the cone cells. The response in the rods is driven by cone cells and mediated through horizontal cells. These horizontal cells connect rods and cones through their dendrites and long axons, and at the same time form a mesh of connections among each other. The hyperpolarization of one cone thus leads to the depolarization of many surrounding rods.

During bright light conditions, the cells of the inner retina receive therefore information through two pathways: First through the well-established cone pathway, and second through this newly identified rod pathway. “We think that the surround information relayed to the inner retina through the rod pathway has different functional properties than the information obtained through the cone pathway,” comments Roska. “In any case it is fascinating to see how the retina repurposes the rod cells during bright light conditions to increase contrast information, at times when they are not directly sensing light.”

After all, these large numbers of rods don’t seem to be present in the retina in vain.

5

Brainbeauty: Did you know chickens ‘one-up’ humans in ability to see color?

The retina contains two types of cells, rods and cones. Rods handle low light vision where as cones handle color vision and detail. A series of complex chemical reactions occurs when light contacts these two types of cells. The number and ratio of rods to cones varies among species, dependent on whether an animal is primarily diurnal or nocturnal.

Birds have five types of cones including four single cones and a double cone thought to mediate achromatic motion perception. Birds have a cone photoreceptor for violet/ultraviolet light in addition to the red, blue and green single cone cells that humans share. Much however is still unknown about the spatial organization of avian cones and the adaptive significance. 

The vibrancy of avian color vision is currently thought to be a result of not experiencing an evolutionary nocturnal period. In contrast, mammals spent millennia as nocturnal organisms and developed a high density of rod photoreceptors. Since chickens possess minimal rods, mammals still have the ‘one-up’ in the dark.

Bipolar Cells of the Mouse Retina

In the retina, bipolar cells are situated between photoreceptors and ganglion cells. They act, directly or indirectly (via amacrine cells), to transmit signals from the photoreceptors to the ganglion cells. Each bipolar cell can synapse with either rods or cones, but not both (hence the name “bipolar”). There are ten distinct types of cone bipolar cells in the mammalian retina, and only one type of rod bipolar cell (stained red in the image above).

Bipolar cells can be further classified as “ON” or “OFF” based on how they react to changes in the release of glutamate by photoreceptors. When light hits a photoreceptor cell, the photoreceptor hyperpolarizes and releases less glutamate. ON bipolar cells (stained blue in the image above) will respond to this change by depolarizing and OFF bipolar cells will respond by hyperpolarizing.

Image by Luca Della Santina, courtesy of Rachel Wong, University of Washington.

An important scientific breakthrough in the fight against blindness

A team of researchers at the IRCM led by Michel Cayouette, PhD, identified one of the genes responsible for producing a type of cell required for vision. The breakthrough, published in the scientific journal Neuron, could eventually help overcome obstacles associated with treatments to prevent blindness.

The retina of the eye is made up, in part, of two types of photoreceptors (light-sensing neurons): rods that enable night vision, and cones that are used for high visual acuity and colour daylight vision. The loss of cones is a major cause of blindness associated to various retinal degenerative diseases, and the scientific community is working towards restoring sight through cell replacement therapies.

“Retinal stem cells produce all types of retinal cells, including rod and cone photoreceptors,” explains Pierre Mattar, PhD, first author of the study and postdoctoral fellow in Dr. Cayouette’s laboratory. “The scientific community has been successful in generating rods from stem cells and has even used them to restore sight in mouse models of blindness, which shows that this approach is promising. However, the production of a large number of cones continues to be very difficult, for reasons that remain unknown.”

During normal development of the retina, stem cells produce the different types of photoreceptors according to a precise time sequence. They produce cones first and, later, will produce rods. The IRCM researchers identified, for the first time, one of the genes involved in this temporal change, the Casz1 gene.

“We discovered a cascade of genes that allows the sequential production of photoreceptors and other retinal cell types over time,” says Dr. Cayouette, Associate IRCM Research Professor and Director of the Cellular Neurobiology research unit. “This cascade appears to be conserved from flies to mice, which suggests that it might represent a fundamental mechanism to control stem cell development that could also be conserved in humans.”

“The current methods to produce photoreceptors from retinal stem cells do not take into account the temporal identity of stem cells or, in other words, when they are most likely to generate cones or rods,” adds Dr. Cayouette. “Our findings now provide a novel way to control this process. Manipulating the Casz1 cascade could allow us, for example, to extend the cone-producing window, thereby increasing the generation of cone cells that could be used in treatments to reverse blindness.”

Ok so I know lots of other people have provided scientific explanations for the dress - and I’m gonna provide another simplified one. I’m a neuroscience student, and I research visual perception at my job, so you can trust me on this!

Basically: everyone genetically has slightly different ratios of colour receptors in their eyes, which results in everyone actually seeing colours slightly differently. Furthermore, everyone has slightly different amounts of the main protein that senses light intensity - called rhodopsin - in their rod receptor cells in their eyes (this is also due to genetics). So everyone had different sensitivity to light.

In pictures with dim lighting and directly inverse colours, such as the dress one, those differences between people are really noticeable. Light sensitivity is a part of this -  if you are less sensitive to light, you are less likely to notice the colours and see white and gold. If you are more sensitive, you see blue and black. It may also be a difference in blue channel cone expression.

Also, in this photo, there are likely optical illusion effects (such as after-image) can make it even harder to categorize the colours.

TL;DR everyone sees colours differently due to genetics, both sides are technically right, everyone chillax it’s all good!

In case you wanted to know...

It’s blue.  There is no debate, that is the physical reality of the situation.

tl;dr: Your brain got confused on the lighting context of the object it was looking at and so while creating an image for you to perceive it miscalculated the color of the dress, similar to a camera in artificial light.  If you want to see the actual color of the dress just look at it through your phones camera which will properly color balance the image.    

Getting that out of the way, why does it look white and gold? Unfortunately people are passing around false information that so many blindly listen to.  

The reason that anything looks like anything is because our eyes have four important types of cells (three types of cone cells and rod cells) that are responsible for collecting four streams of data for our brains to interpret.  

Each eye measures overall light level, this is done by your rod cells, and the three different types of cone cells measure specific wave lengths of light.  While these sensitivities will differ from person to person, they are fairly uniform. They are uniform for a very good reason, human beings need high color accuracy to survive.  While some animals use other senses such as hearing in echolocation to perceive the world around them, humans use our highly sensitive eyes.  So if we could only see overall light coming off of an object anything that reflected a similar amount of light would appear to be the same object.  

So using all this data, and the differences from the light one eye picks up to the other, the brain can create an image that we can use to navigate the world around us.  This is where the dumb dress comes back into play.  

The dress is simply an optical illusion.  Depending on who looks at it, and with what display they are reproducing the image, the dress will be a slightly different color.  Now obviously this is a special case otherwise this problem would have come up before many times. 

The reason that this dress looks so dramatically different is the lighting of the photo, and our brains natural response to put everything in the context of sunlight, which our eyes are optimized for. 

To make it easier to understand, think about your eyes and brain like a camera.  The sensor (eyes) is picking up light, and the software and processor (brain) are trying to make sense of it all.  The camera looks around at stuff and tries to auto white balance so it can adjust the image to keep colors true to life.  If you bring your camera into a room that is only filled with one color of light it get’s very confused as it can not differentiate colors properly because it has no other colors to reference, so it will keep trying to no avail to white balance a room that only has one color, and so one small part of the spectrum of white light.  If you want to see the dress for its actual color you can either color balance it with an image editor, or you can point your phone at the screen and let it auto color balance the image.

This is how optical illusions work, you see something, your brain tries to put it into context, and the perceived context differs from reality.  Our brain is getting information that it logically knows must be false based off of our past experiences and our understanding of the world, and yet the only way that it can put the information from the eyes together is to defy what we know to be true.  This is however not something we are entirely powerless to.  Our brains can be trained to perceive things differently, and then our perception will morph to be back to what it was naturally before the artificial perceptual skew altered the data coming to us. You need only look at the famous experiment by George M. Stratton in which he tested the brains proficiency for perceptual adaptation.  

So, to sum this up. 

Depending on who/where/when you saw this image, and under what context your brain was referencing white light for color comparison, you could have seen a different image.  This image is very curios because the light coming from it tricks many peoples brains into perceiving it at as being a very different color.  

If the dress you saw was white and gold, you’re not wrong about what you saw, but your brain is wrong about what it thinks it is seeing.  Our senses only collect data, while our brain is what turns it all into usable information.  This image just happens to confuse a lot of brains.   

This is a very simplified explication of a mental phenomenon that I’m am equally fascinated and confused by, so please take all of this under that light (intended) and read more into it yourself, and tell me if I got anything wrong.

anonymous asked:

OK SO ON THE NORMAL PIC ITS WHOTE AND GOLD BUT ON SHANES PHOTO ON IG Its blue and black?!! (Shane dawson)

Okay apparently it has to do with how the rod and cone cells in your eyes perceive the photo’s dimness, and seeing them alternating could be from the dimness of your room or the tilt of your phone. But I finally see the blue and black in Shane’s picture so omf this is so messed up.

landof-thecrazies replied to your post: wait how is the dress white & gold

it only looks white and gold in the shade to some people due to poor eyesight because of their rod cells. if you see it blue and black you have superior vision.

i just looked this up bc i am a nerd, but yes :-) & also this:

"Your eyes have retinas, the things that let you interpret color. There’s rods, round things, and cones that stick out, which is what gives your eye a textured appearance in the colored part. The “cones” see color. The “rods” see shade, like black, white and grey. Cones only work when enough light passes through. So while I see the fabric as white, someone else may see it as blue because my cones aren’t responding to the dim lighting. My rods see it as a shade (white). There’s three cones, small, medium and large. They are blue sensitive, green sensitive, and red sensitive.
As for the black bit (which I see as gold), it’s called additive mixing. Blue, green and red are the main colors for additive mixing. This is where it gets really tricky. Subtractive mixing, such as with paint, means the more colors you add the murkier it gets until it’s black. ADDITIVE mixing, when you add the three colors eyes see best, red, green and blue, (not to be confused with primary colors red, blue and yellow) it makes pure white.—Blue and Black: In conclusion, your retina’s cones are more high functioning, and this results in your eyes doing subtractive mixing.—White and Gold: our eyes don’t work well in dim light so our retinas rods see white, and this makes them less light sensitive, causing additive mixing, (that of green and red), to make gold.**** UPDATE to prove this theory I turned my phone brightness from the lowest to highest and saw it switching from white and gold (at the lowest) to light blue and darker gold (at the highest) meaning people that see blue and black are more sensitive to light (better eyesight and not looking at the sun like your moms told you)” x

Guys the only reason some people are seeing white and gold vs blue and black are because of the amount of cone cells (which detect color) and rod cells (which detect light) in our eyes

It really just depends on your genetics, if you see blue and black im pretty sure you just have more cone cells ? And vice versa w/ rod cells+ white and gold (im not entirely sure on the specifics here pls correct me if its wrong)

There, its over, we can stop now

the-surfing-pikachu asked:

Basically in your retinas there are two kinds of cells, rods and cones. Cones make you see color (red, green and blue) and rods make you see shades (black, white, grey). By mixing those, you get all the colors in the spectre. On dim light, your cones don't work well and the colour blue is percieved as white. As for the black part, when your red and green cones mix up without blue, you see gold. If you see blue and black you have a better eyesight in dim light. If you see both you're average. :)

Damn my eyes suck then lol thanks for the info

anonymous asked:

WHAT ABOUT WHEN IT CHANGES FOR ME IT SWITCHES SOMETIMES.

Now that could be due to adaptation of your rod receptor cells. Basically, if your eyes keep seeing the same light signal, they get “tired” and stop sending info about it to the brain. So let’s say at first you see black and blue, but then your rods adapt to the intensity of the light, and so you may receive less info about the light intensity to your brain, and thus you might perceive it as “dimmer”, which makes it look white and gold, instead.

Another possible explanation is that when you try to see it in a different way, you are unconsciously focusing your eyes on particular features that fit that perception so you’re seeing it the way your brain wants to. For people who can’t switch even when they try, they likely just don’t have the right level light sensitivity and/or don’t have the proper combo of colour receptors to see it the other way.

"Color: Is it Real and Does it Impact Our Behavior"

The scientific definition of color fails to capture the importance that color has in our world. From a scientific perspective, color is defined as a sensation produced in the brain by light that enters the rod cells — one of the two types of photoreceptors found in the retina of the eye - via the absorption/reflection of different wavelengths and frequencies of photons (1). When light is transmitted from an object to the eye, it stimulates the different color cones of the retina, therefore making the perception of various colors in the object possible. This definition is limited because it does not answer the important question about whether color is real or just a function of our brain. It does not establish that color is extremely important in the way we perceive the world today, regardless of whether color is real or not.”


-Ebony Dix

http://serendip.brynmawr.edu/bb/neuro/neuro06/web2/edix.html

闹眼睛:这裙子到底啥颜色?

This photo of a dress has caused an internet uproar: Is it blue and black, or white and gold?
这张照片让网友们吵翻天了,到底是”蓝+黑”还是”白+金”啊?

So far, according to Buzzfeed, about three-quarters of respondents see white and gold.
截止目前,Buzzfeed的投票显示,3/4的人认为这条裙子的颜色是”白+金”。

But why are people seeing such wildly different colors? First off, it’s not monitor settings.
为什么不同的人看到的颜色差别这么大?首先给显示屏洗脱冤屈吧。

It’s probably not about the cells in your eyes.
与视网膜细胞貌似没啥关系。

Our retinas have specialized cells called rods, which are used for night vision, and cones, which deal with color. But these cells are probably not the source of the dress dilemma.
视网膜中有视杆细胞,负责夜视,以及视锥细胞,负责颜色。但这些细胞并不能解释这条诡异的变色裙子。

Cones come in three types: red, blue, and green. And each of us has very different ratios of these types. But the different ratios “don’t seem to have a big impact on our color vision,” said Cedar Riener, associate professor of psychology at Randolph-Macon College. “I could have a 5-1 ratio of red to green cones, and you could have 2-1, and we could both have similar color sensitivity.”
伦道夫-麦肯学院心理学副教授Cedar Riener解释说,视锥细胞有三种形式:红、蓝、绿。不同的人眼睛中这三种形式的视锥细胞比率都不尽相同,但是这并不影响我们对颜色的认知。比如我可以有红:绿=5:1的视锥细胞,你的是2:1,但是我们看到的红和绿是类似的。

It’s about how your brain is interpreting the light coming into your eyes.
是你的大脑如何解释进入眼睛的光。

The dress phenomenon, according to neuroscientist Dale Purves of Duke University, “shows how strongly people are wedded to the idea that colors are properties of objects, when they are in fact made up by the brain.”
杜克大学神经系统学家Dale Purves说这条诡异的裙子很好的说明了一个问题:”人们根深蒂固的坚信颜色是物体本身的属性,其实它们不过是大脑的解释罢了”。

OK, but why do different people’s brains interpret the light differently?
好吧,但是为什么每个人的大脑给出的解释都不一样呢?

Our vision is heavily influenced by so-called “top-down” processing, John Borghi, a cognitive neuroscientist at Rockefeller University, told BuzzFeed News. Top-down processing “begins with the brain and flows down, filtering information through our experience and expectations to produce perceptions.”
洛克菲勒大学认知神经系统学家John Borghi解释了我们视觉形成的过程:视觉是一个从上向下的过程,从大脑开始,根据经验和预期向下过滤信息,直到产生视觉。

Each person brings a different set of experiences and expectations, as well as attention levels and particular eye movements.
每个人的经验和预期不同,关注程度以及眼球运动也不同。

For example, what you looked at just before you looked at the dress could influence the way your brain perceived it, Borghi added. “It could also be that you’ve seen dresses (or fabric) with the same texture or shape before, which could also affect your perception.” This general phenomenon is called priming.
Borghi打了个比方,你看这条裙子前看了什么可能影响你看到这条裙子的颜色。”如果此前你看到过与这条裙子材质或形状相似的裙子(或织物),也可能影响你的视觉。”这叫启动效应。

Vocabulary
uproar:骚动、哗然
retina:视网膜
ratio:比例
neuroscientist:神经系统科学家
filter:过滤
phenomenon:现象

(来源:中国日报网双语新闻 编辑:张默)

ACTUAL SCIENTIFIC EXPLANATION FOR WHY THE DRESS SEEMS TO BE DIFFERENT COLORS:

Some people think this is caused by emotions, some people think it is the rod cells.

FIRST OF ALL. ROD CELLS SEE LIGHT, NOT COLOR. CONE CELLS SEE COLOR. WHY DOESN’T ANYONE EVER CHECK IF WHAT THEY HEAR IS CORRECT?
If the cone cells in your eye were bad, you would be color blind. Not tricked by an optical illusion. If the rods were bad, you would have no peripheral vision.
And really? Emotions? No. Just no.

There is a thing our brains do to figure out what color something is in different lightings, such as if you are in a room with all blue lights you can still kinda tell what color things are

Some people see it as in a blue lit room (white/gold people), some people see it in a very yellowy room(blue/black people)
I see it as the person who took the photo really sucks at white balance (making the colors in the photo accurate) (i see light blue/dark gold normally, so i guess my brain doesn’t do that thing.

The ACTUAL dress is blue and black, its just weird lighting and bad camera skills, and that it just happens to accidentally be an optical illusion. 

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ตอนนี้ที่ทำงานผมเห็นภาพนี้แล้วกำลังถกเถียงกันว่ามันคือสีอะไร ระหว่าง ขาว-ทอง กับ น้ำเงิน-ดำ ผมก็มากว่าทำไมเห็นไม่เหมือนกัน เห็นเป็นสีอะไรกันครับผม #ทีมขาวทอง

เสื้อตัวนี้สีขาวทอง หรือ ดำน้ำเงิน! ปริศนา(น่าจะ)ไขกระจ่างแล้ว !?!
เป็นประเด็นที่คนถามกันมากมายจากsocial mediaต่างประเทศ ว่าชุดนี้สีอะไร
ในต่างประเทศ คนลงความเห็นว่า ชุดนี้ขาวทอง 70% ดำน้ำเงิน30%
ในกูเกิล ถ้าครอปภาพไปบางส่วน กูเกิลจะดึงภาพมาไม่เท่ากัน เช่น ถ้าโยนภาพนี้ลงไป จะได้ของสีขาวหม่นปนเหลืองมา … แต่ถ้าเอาภาพที่มีเฉพาะชุด จะได้สีน้ำเงินดำมา
ตะกี้ถามในห้องพักแพทย์ 80%บอกว่า ดำน้ำเงิน 20%บอกว่าขาวทอง
กับบางส่วนเปลี่ยนมาเลือกขาวทอง เมื่อขยายภาพ
กับพี่หมอท่านนึงที่เป็นตาบอดสี บอกว่าน่าจะเป็น น้ำเงินดำ
ในinternet เวลาปรับGamma หรือเพิ่มแสง คนก็เปลี่ยนสีที่รับรู้ได้
ดังนั้นหมอแมวสรุปว่า คงเป็นเรื่องของ entoptic phenomenon ที่เกี่ยวกับการรับรู้สี
เพราะการรับแสงสีขาวแบบชัดๆ ต้องอาศัยการทำงานของทั้งเซลล์รับแสงทั้งRod กับCone กับอาศัยการผสมแสง (แดงเขียวน้ำเงินรวมกันเป็นสีขาว)
การทำงานของ Cone ของคนทุกคนทำงานต่างกันเล็กน้อยอยู่แล้ว เฉดสีที่รับได้ก็ต่างกันเล็กน้อย
การทำงานของ Rod ที่รับความเข้มแสง เวลารับแสงสีขาวก็จะคล้ายๆกล้องถ่ายภาพ คือเวลาถ่ายภาพสีขาวจัดๆจะกลายเป็นสีเทา ตาคนเราบางคนเวลามองสีขาวจัดก็มองเห็นเป็นสีน้ำเงินหรือฟ้าได้ กับยิ่งมีสีอื่นเทียบ สีจะเพี้ยนขึ้นกว่าเดิม
(อธิบายอีกทีให้สั้น
สีขาว เวลาแสงน้อย เราจะเห็นเป็นสีฟ้าหม่นอยู่แล้ว พอเจอสิ่งท่ีเหมือนสีเหลือง อยู่รอบๆ จะเจอตัดแสงไปอีก สมองจะมองเป็นสีน้ำเงิน
กับสีเหลืองทอง ถ้าเจอสีฟ้ามาขนาบข้าง สมองจะปรับแสงมองเป็นสีดำ)
แล้วคุณมองเห็นสีอะไรครับ
ปล. ใครที่มองเป็นสีขาวทอง ให้มองไปที่ขอบภาพส่วนที่เป็นสีดำแล้วหรี่ตาครับ (ลดการทำงานของCone cell กับเพิ่มการทำงานของ Rod cell คุณจะเห็นเป็นสีน้ำเงินดำเอง)
ปอ. ชุดจริงเป็นสีน้ำเงินดำ (ตามที่คนหลายๆคนแจ้งมา)
ปฮ. ในนี้พยายามพูดถึงเหตุที่บางคนมองเป็นน้ำเงินดำ บางคนมองเป็นขาวทอง บางคนมองได้สองสีว่าเป็น entopic phenomenon (ในกลุ่ม optic illusion แต่ไม่ใช่ optic illusion 100%)

ที่มา : ohozaa

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