memorize 7-6.4 hehe

So ligh enters the corenea and it will bend it, this is calle refraction. The light will enter the cornea and refract the light to adjust it onto the lens where the lens will fine tune it and send it to the retina for transduction so it sends neural signals to the brain. Again so light enters the cornea and bends it, refraction onto the lens where the lens will fine tune the image onto the retina where it will go through neural transductionn. The lens will fine tune the image through the ciliary muscles thaht will make the image focus onto the retina.

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Light wil enter the cornea, refraction/bend it into the lense where ciliary muscles will fine tune the image onto the retina. the ciliary muscles in the lense will contract. myopia is nearsightedness where u cant see from far away. the eyeball is too long in myopia where the image from far away will focus infront of the retina so it is blurred. What glasses do is that they will bend/refract the light before it even enters the cornea so the image is focused sharper onto the retina.

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Light goes into the cornea where it will refract the light onto the lens where cilary muscles will contract and focus the image onto the retina. Although myopia is nearsighteness where the image is focused infront of the retina this is why it is blurry. So glasses will already refract the light before it even enters the cornea to make the vision more focused.

THE MF RETINAAAAA-

the retina has photoreceptors called rods and cones. they are sensory neurons that detect light. These photoreceptor rods and cones will release neutransmittors onto bipolar cells and then they will release snapses onto ganglion cells and then the axons off the gangilon cells will form the optic nerve which carry infromation to the brain.

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Corenea gets light - lense cilary musclese - retina where photoreceptor sensory neurons rods and cones will detect light and repsond to wavelengths and color. Cones and rods will relaese neurotranmitters onto the bipolar cells, ganglion cells and their axons will become the optic nerve. the retina has photorecepto cells cones and rods that will detect the lighht and then will release neurtransmitters onto the bipolar cells, then ganglion cells where its axons will become the topic nerve that carries infromation. then theres horizontal and amacrine cells that also intereact with the retina. So cornea-lens-retina-photoreceptor cones and rods-bipolar-ganglion-opticnerve-brain.

AGAIIINNN - corenea-lens cilary muscles- retina photoreceptor rods - bipolar-ganglion—-optic nerve axons -brain

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SCOPTIC system is a rod sytem that is very senstive and works in low light and insenstive color- SCOPtic system involves rods that reponds to low light but doesnt detect color. Photopic is cones and detects higher light and color. rods converge onto each ganglion cell and cones only converve onto one ganglion cell.

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the scoptic system involves rods and these rods only detect low dim light and dont detect color and have many converges to ganglion cells. THe phototopic system is thhe cones and detects high light and color and fewer converges.

Summary - Ligh goes into the cornea then refract light onto the lens where cilary muscles will contract onto retina where photoreceptor neurons rods and cones will detect the light. Then they will release neurotransmitters onto the bipolar cells , then those onto ganglion whhere its axons will from the optic nerve and send infromation to the brain. THen cones and rods - scoptic system is rods that will detect low light,, no color and form many converges onto ganglion cells and photopic is thhe cones that detect more light, color, and fewer convervges onto ganglion cells.

Light goes onto retina, photoreceptorr cones and rods detect light, they detect light because they have a stack of disc where the light particles are detected. light will hit the eye and only a fraction of it will reach the retina, so disc increase the proabbiluty thaht one of them will capturea photon(light particle). So thehse discs inside the rods and cones… they have photopigements called rhodopisns, the disc will capture light through photpigemnts in the rods called rhodospin.

AGAIINNN so light will hit the retina where photoreceptors cones and rods will detetect lighht through discs that will catch these photon light particles and they have photopigments called rhodpsins that will catch these light. so these disc will increase the surface area that allows for light to hit. when light hits the photopigment it will cause a chemical cascade where it will lead to signal transduction pathway of neural signals being sent to the brain.

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image focused onto the retina, light is detected by photorecepto rods and cones that hvae these discs that will increase surface area for light photons to hit and inside the discs are photopigemtns that when light hits will cause a chemical cascade /reaction to allow for signal transduction pathway or neural signals being sent to the brain and neurotransmitters are hit. It will trigger a chemical cascade that will hyperpolarize the cell and cause the cell to release less enutransmitters onto the bipolar cellls. THis is because photoreceptors in the dark release neutranmitter on bipolar cells so when light hits it will stop the neutrotamitter releasing onto bupolar cells.

HUHHH—— so glutamate is constantly being released onto bipolar cells when it is dark. So when light hits these photopigements a chemical cascade is released where it will hyperpolarrize the cells and stop the gluutmate from going into the bipolar cells. This in turn causes the bipolar cell to release a signal to ganglion cells.

Light intensity wil cause the size of a pupil to change. So what happens is when there is a lot of light the pupil will decerase and with low light will become bigggg. This is cause of the iris whhich is thhe opining for the pupil that opens or closes. sOOOO SOOOOS OSOO the pupil size gets bigger or smaller because of the iris which opens or closes. So in dark light the iris opens more so the pupil is bigger to allow more light to come in.

AAGIIINNN so photopigments get light and this stops the release of gllutumate to the bipolar cells which will cause for bipolar cells to release a signal to ganglion clels into the brain. And when light is high the pupils will be small to miminizze the light cominign in because the iris closes.

so when light comes in it reaches the retina, and the fovea that is compact with cones that absorb the light. the rods are outside the fovea. visual acuity is high here. This allows us to have a visual field or pheripheral vision. So what we look at is more sharper than the iamge around us because the fovea is in the center. The whole area where u can see without moving your head or eyes is called visual field. Visual acuity is the sharpness of vision. It is fine in the center but blurry around the visual fiedl. The fovea is the fune strtucture of the retina and explains why our vision or acuity is best in the center. THis is because the cones are more densly packed in the fovea. they absorb more light. higher vision means more cones in the fovea. rods are around the fovea. rods = dim light cones = bright light. the light reaches the fovea without having ot pass through layers of cells and blood vessels. the axons of ganglion cells will makeup the otpic nerrve. So eachh eye will have a optic nerve

SOOO EXPLANiAITON. each eye has a optic nerve. The optic nerve has two sections of fibers one nasal and one temporal. It will reach a section of the brain called optic chiasm where the fibers of the optic nerve clsoes to the nose (nasal retina fibers) will converge to the opposite side and the temporal side will continue to the same side.. after the optic chaism each side will reache the optic tract.

√So the fibers cross over at the optic chiasm then will proceed to the optical tract. It will carry information from both eyes some fibers will go to the LGN and others will go to the superior colliculus midbrain involved in rapid eye movements. . .. in the superior colliculus midbrain the fibers play a role in eye movements and focus on targets. In the LGN visual information proceeds to the next step. Some axons are terminated? … then LGN information proceeds to the optical radiations. Where information will carry out to the primary visual cortex v1 in the occipital lobe. The primary visual cortex v1 located in the occipital love in the back of the brain is known as the striate cortex. The information from both eyes is processed.

SUMMARY OF THE WHOLE THINNGGGGGGGGGGG—

light comes in and reaches the cornea, this is where the cornea will refract the light or bend it into the lens where ciliary muscles will contract in order to focus thhe image onto the retina. when this happens it will be caughht by discs in photoreceptor cones and rods. the disc increase the surface area for photons to hit the retina. inside these discs there are photopigments that when hit with light will lead to a chemical cascade. when it is dark neurotransmitter glutumate is released from photoreceptor to bipolar cells so the cell is depolarized although when light hits these photopigments glutamate stops being released onto bipolar cells which then causes a signal to be send to ganglion cells. fovea in the center of the eye in the back of retina where it is compacted with cones therefore the center of our visual field is more sharp because around the fovea there are rods therefore expalisn that our visual field is blurry around the pherpheral but in the middle our visual acuity is sharp. scoptic refers to rods that work in dim light and dont detect color and converge a lot onto ganglion cells and photopic referes to cones that work in brighter light and converge less and detect color. so the processes of infromation being sent to the brain starts whwen retina sends singals to the bipolar cells and then to the ganglion cells where its axons will become the optic nerve. each eye has two fibers of this optic nerve where it is closer to the nasal side or temporal side. both optic nerves of both eyes will reach the optic chiasm where the nasal fibers will cross over to the opposite side of the brain and the temporal side will remain. then these fibers will reach the optic tract where some parts of the fibers will go to the superior colliculus of the midbrain where it works with eye movements and focusin onto targets and the other fibers will proceed to the LGN of the thalamus. and then from the LGN go to the optic radiation that will carry infroamtion to the oocipital lobe or primary visual cortext v1 that is the striate cortext that receives and proccesses the infromationn of both eyes.

7.2

light hyperpolarizes phhotorecepotrs and causes glutmatmet to stop being sent to bipolar cells. Glutamate in bipolar cells is inhibitory. So dark release glutatmate and stops bipolar cells. So lgith will stop glutamate and will start bipolar cells.o

On center bipolar cells - so light on the center of the bipolar receptive field will excite it. Off center bipolar cells, light shining will inhibit the bipolar cells. Off center bipolar - thhe middle is dark therefore needs light to be off to excite it.

So lets reexplain this. in an on center bipolar cell liight will hit the center and therefore will deopolarize the bipolar cell. So bipolarr cells are stopped by glutamate. When there is no light photoreceptors will release glutamte to the bipolar cells. So when there is light, no gluamate is released and the light will hit the center of the bipolar cell and therefore deoplarize it and cause it to release singals to the ganglion cells.

so in on center bipolar cells glutmamtate is inhibtory

In off center bipolar cells glutamate is excitatory. So when light comes in and hits the photopigments it will lead to less glutmatame and therefore will lead to less singals sent to ganglion cells and decrease firing rate.

So on center bipolar cells - glutamate is inhibitory and in off center bipolar cells glutamate is excitatory. When it is dark glutamate is released onto the bipolar cells. The bipolar cells acts differently depending on if the bipolar cell is on or off center. On the on center bipolar cells glutamate is inhibitory so when light hits the center of the receptive field which is the center of the on center bipolar field, it will cause a decrease in glutamate release from photoreceptors and depolarize the center of the bipolar cell and send signals to the ganglion cells. But when light hits the center of the off center bipolar cells it will lead to decrease glutamate release and therefore will hyperpolarize the off center bipolar cell and lead to a decrease in the signals sent to the ganglion cells. So in the dark when there are off center cells , darkness will hit the center of the off center bipolar cell and then cause an increase of glutamate and therefore depolarize the cell.

soooooooo like lets come back to this. There are two types of bipolar cells there are the on center bipolar cells. these on center bipolar cells have a light center and a dark center. What happens is that light will stop the productinon of glutmamate, and therefore light will also hit the on center of the bipolar cells. then this causes an excitatory deopolarization of the cell and cause and action potential release onto ganglion cells. then if light hits the dark surroundings of this cell then it will lead to more glutamate to be made and therefore horizontal cells to inhibit these bipolar cells.

SOOOO light hits the center of the on center cell and this will cause less glumamate to be made and therfore will deopolarize the cell and if light hits the surrounding which is dark then it will actually lead to more glutmatate to be made and the horizontal cells will be the ones to inhibit the on center bipolar cell

So when light hits the center of the off center cell this will cause for

on center cell - glutmamte will depolarize

off center cell - glutmamte will hyperpolarize

When light hits the center of the off center bipolar cell It will lead to a decrease of glutamate therefore since glutamate is excitatory for off center bipolar cells the reduction will lead to hyperpolarize. So when light hits the surrounding which is white then it will lead to an increase of glutamate which then will lead to a depolarize of the bipolar cell

on center - center is white surrounding is black

off center - center is black surrounding is white

on center - glumaate is inhibitory

off center - glutmate is excitatory

light hits the center of the on center and this causes for the glumate to stop releasing and will lead to depolarization of the cell

Light hits the center of the off center and this causes for glumate to stop releasing and therefore lead to hyperpolarization of the cell

the light hits the center of the off center cells and leads to less production of glutamate and then the amacrine cells will hyperpolarize the bipolar cells?

On center cells - light hits the middle and therefore this decreaes the making of glumatate and will deopolarize theh cell

Off center cells - light hits the middle and this decreases the making of glumaate and therefore will hyperpolarize the cell thourgh amarcrine cells

thhe sourrdoungings of the oncter - light will hit the surddounf and will lead to the increase of glumaate and therfore horiztonal cells will hyperpolarize the bipolar cells

The surroudning of the off center cells - thhe light will hit the sourrounding and therefore lead to a increae of gluamate and therefore lead to depolarization off the cell

off center -glumamate will excite theh cell - therefore hates light in the middle because it will stop glumamate and the cell will not reach action potential.

On center - glumamate will inhibit therefore likes light in the middle becausde it stops glumamate

so cortical cells are in the straite cortext/v1/occipital lobe/pimrary visual cortext. The simple cortical cells have a distinct on or off where light has to hit the on to detect, edges, spatial locaiton, bars. but the compleext cortical cells dont have a distinct on or off because they detect motion and curves.

spatial frequency model - visual system analyzes the numer of cycles of light dark patches in any stimulus. some cucles are narrow and others are braod . cortical cells repond better to patters of light than a single bar of light. Some neurons in the v1 are tued to speciif sptail frequencies where some repond better to fine or borad sapes. it analyzes the number of dark light cycles in any stimulus. cortical neurons will detect dark light cycles and respond to repeatind boards of light better

so some areas of the brain will respond to specific patters of dark and light. v2 will respond to illusory contours, v4 to concentric and radial sitmuli and color differences, v5 repsonds to visual moving sitmuli

7.3

photors vary in frequncy of vibration wavelengths of light can be detected as blue green when its fast and slow is orangge and red.

there are three dimension of color preception - brigtnes, hue,and saturation

and there are three different types of cones with seperate pathway to the brain. color is reconzied based on which receptors are activated. then opponen process hypotheisi of color perception, there are unique hues, three opposed pair of color. the responds of each cone depends on which wavelength of light its pitment is absorbed. trichormatic is the three types of cones detecting color . small waves is blue, medium is green and large is yellow