Relearn from zewo — all about vision

the light will enter the eye through the cornea will the light will becomre refracted onto the lens where the cillarymuscles will contract and tune the image onto the retina. myopia is near sightedness so glasses will be used in order to refract the light before it hits the cornea in order to sharpen the image more. Also there is the pupil and the iris and the pupil wil become bigger at night because the iris will open and allow more light to enter the pupil the eye and when its too bright the iris will shrink and the pupil will be smaller to minimie the amount of light coming in so its not too harmful.

in the retina there are photoreceptors cones and rods. Rods work in dim light and converge to many ganglion cells, so cones and rods have these discs that will maximize the area to have light come in and hit it and when light hits it hits a photogiment. when photogiment is hit it will cause a chemical cascade. also the rods system is scoptic and the cones is the photonic which the cones is related to more light and color. Also the visual acuity is better in the center when we focus on an object because the fovea that is in the center of the retina is packed with cones which explains our more sharpened sense. Also around the fovea there are more rods so when we want to look at a dim object its best to look at it from our side so our peripheral vision is worse due to lack of cones. ANywho so the signal goes from our retina, to bipolar cells, to the ganglion cells where the axons will form the optic nerve in which will reach to the optic chiasm were the fibers of each eye will cross over to the other side. So the eye has two nerve fibers one close to the nasal side and one on the termpal side and so the one on the nasal side will cross over to the other side where then it will reach the optic tract …. LGN… Optic radiation… primary visual cortext v1 occiptial lbe .

things i need to reclarify and learn.

so the photopigments in the disc are called rhodospins. photopigments are called rhodopsins. at night there is always gluamate being released into bipolar cells. in some bipolar cells this is inhibiting. So when light comes in it will stop the glumatamte and thsi excites the bipolar cell so therefore will release action potential into ganglion cells and cause infromation to be released. glumate hyperolarize the cells. also the light passes to the fofvea without going through blood cells or layers of the cell.

again so once the fibers cross over at the optic chiams then what happens is that the fibers will go to each hemispheres optic tract. Some of the ifnroamtion will gog the LGN and other to the superior colliculus midbrain involved in rapid eye movment and focusing on eye targer.

Superior colliculus in the midbrain. Some nerve fivers to go the superior collicus in the brain for target movment and rapid eye movments. Others will go the LGN in the optic tract. Then from the LGN will go to the optic radiation where infroamtion is carried out to the visual prikary cortext in the occipital lobe known as ths traite cortext.

again so the infromation from the optic chiasm wil enter the topci tract will some fibers will go the supeiror colliclus in the midbrain in order to engage in rapid eye movemnt and target focusing. Also the others go to the LGN where the information will go to the radiation and then the primary visual cortex in the occpital lobe known as the strait cotrex. this is wher einrfomation from both eyes is

there are some bipolar cells that will be either inhibited or excited by glumatate.

So on center cells are inhibited by gluamate and off gener bipolar cells are excited by glumatamte. So when the light hits the center of these on center bipolar cells then glumate production stops and therefore what happens is that the bipolar cell is deoplarized and releases action potential to the ganglion cell. But if the light hits the off center then the glumate production stop and therefore the cell will be hyperalized becuase these off center bipolar cells is excited by glumatmate.

photoreceptors release neutoramsitter gluamtae onto bipolar bipolar cells.

then there are cortical cells which are in the V1 straite cortex. simple cortical cells have distinct off on regions where light has to hit these regions to detect edges, spatial location, and bars. But in the compelxt cortical cells these cells dont have distinct on off regions where when light is moving it hits it can detect curves and motions. So these simple cortical cells reiceive infromation from bipolar cells and then a row of simple cortical cells will send information to complex coirtcla cell. So row of bipolar cells send info to a simple and a row of simple send infromation to a complex. agtain so the simple edtects edges and psatial location and has distinct on off regions where light needs to hit but complex detects movment and curves and doesnt have distinc area.

spatial frequency ‘ says sthat dark and light cycles is better. cortical neurons detect dark like cycles of patterns. eac cell fires better to pattern of particual oritnetation. Again so cortical nueon cells repsond to dark light cycle patterns. some neruons repond to paarticular pattern frequency. So low patterns of dark light will lead to blurry and high patterson of light dark will lead to better pictures.

row of biplar send signal to simple and row of simple send to complex . more patterns of dark light lead to better imagte and low pattern leads to a more blurred.

cortical area, v2 cortical neruons repond to illusory boundaries and complex relations among the pats of the receptive fields - this means that v2 cortical neurons are fill in the blank that detect abstaract shapes fomed by contexxt. SO v2 reponds to fill in the blank and detects abtract shapes. v4 will decode shape color and texture.

so v2 is abstract tshpanes and fill in the blanks

v4 is about color and shape texture

v5 are about detecting motion

there are cortial neurons simple and complex that are going to detect either edges and spactial location from simple and compex that detect

ahh so v1 is simple and complex and v2 is a whole different thing detecting abstract v4 is color and v5 is movment.

trichomatic hypothesis states that are three differnet types of cones with different pathways that detect color depdning on the patchway. color is percieves on wavelength of photones, so brighness, hues, and saturation. in daylight 2 cones are on nomatter the color. Again so the trichomatic hypothessis says these three diferent type of cones and pathways that detect color and in day its 2 that are on and color is periceved through brightness, staturation, and hue. there are four unique hues. spectraccly opponent cells have oppostite fiirng reposnses to different regions of the spectrum. most ganglion cells and lgn cell fire in repsonse to wavelegnth are are inhibited by tohrs. Againnn So the trichromatic theory says thyere are three diferent cones and paths. wavelengths are periceved as hues four different and brightnes and saturation. And based on the wavelength it will cause lgn or gnagion cells to fire or inhibit. the cell is firing at 600nm wavelnth so large and inhibited by smaller ones.

so red is. at 600nm and blue green is at 500nm

so ganglion and lgn cells is inihbited or fired depending on the waveeltnh. big ones is red and small ones is blue green.

spectrally opponent ganglion cells recieve input from tow or three types of cones throgh bipolar cells and have exitator or ihibitory inputs.

spectrially opoonent cells arent called color cell s because they send outputs to higher ciructrs for detectino of ofmr dpeth and motions,,

so retianl ganglion cells and lgn neurons are considered spectrally oponnent cells that will fire or inhibit depending on the wavelength. In L wavelenths its red and needs 600nm and M wavelenths its ‘500 for blue green. retinal galngion will recieve infromaop form bipolar cells from three or two cones. LGN and ganglions arent color detectors they just send inforation to higher circuits for detection depth and motion.

again so basically light enter the cornea and then the refracted and bends the light onto the lense where cilary msucles will contract the image onto the retina where photoreceptors will detec the light and they have discs that increase suface area and then those discs have photopigments like rhodopsins that when light hits will release a chemcial cascade. before we beign we talk about cones and rods in which cones are the ones in the photopic system that detects brighter light and also color and rods are the scoptic systme that detects dim like and more convergance to ganglion cells. and then there is the fovea in the retina which is packed with cones and catches more like and explains why our centeral visual acuity is better and our peripheral full of rods is worse. and then fovea light doenst go rhogugh cell latyers or blood vessels so its clear in the middle and then when the cascade happens it will cause chem reaction of the light hitting and then production of glumatate stops and glumate is made always in the dark so light comes in and in on center bipolar cells this depolarizes it and in off center bipolar cells this hyperolarizes it . anywho bipolar either will or wont release action potential onto ganglion cells and these gangleion cell axons will form the optic nerve and it has two fibers close to nasla or temporal side and when it goes onto the optic chiasm the nasal side fibers of both eyes will cross over and the temrpoal ones will remain and then after that it will go to the optic tract on both hemipheres wil the fibers will either go to the LGN or the superior colliclus in the mdibrain which is also imfroatnt for eye movemtn or target focusing but the ganglionc ells and the lgn are spectrally opoonent cells that means that depending on the wavelength they will either fire or be inhibited. So like large wavelengths needs 600nm to cause firing and M wavelenths need around 500nm which detects blue or gree, but anywho either way tese lgn and ganglion arent the ones that detect color that something of higher orde. anywho the informaiton goes to the optic radiation where then it is send to the v1 optical lob or stait cotrex. the v1 has cortical cells eiether simple or complex and simple ones recieve input from multiple bipolar cells, these simple cells have distinct on off region where light needs to hit in order to detect edges and spatial locaiton and then these simple cortical row of cells willl give infromation to complex and they dont have distinct regions of on or off where the light hits and detects movment and curves. anywho the v2 wwill detect abstract imagaes and fill in the blank v4 is for color texture and shape and v5 is for higher movment order stuff. oh i forgot there are three diferent types of cones that have different pathways and depending it will give off a color detection and color is detected through wavelengths hues, brightness, saturation all that good stuff. in the day at least two cones are on . whatever continueing about the primary cortex is the two steams for processing called parallel processing. Theres the ventral and dorsal stream and the ventral is used to identify objects and faces and the dorsal is for idneitfying locaiton of objects and guiidng momvents to guid graps to the objects although optic ataxia is problem using vision in order to grapsh for objects.

parallel processing a patways in the visual system. the ventral stream that identifies object and damage to id causes problems in percieving faces and object and the dorsal stream that asses the locaiton of objects and guidementts to them. óptic ataxia is diffuclulty using vision to reach for objects.

two processing streams from hte primary visual cortext. Ventral and dorsal

The ventral is usd to identify objects and damage causes problem in recognizing fafces and objects

The dorsal is used for assesing locaiton of objects and guidign movments to them

and optic ataxia is when u have problems using vision to reach for objects. Again tso the primary cortext has two streams the vedntral and dorsa and cental is for idnetifying objects facees blah blah and the dorsal is used for idneitfying locaiton to the objects and using movments to guide them to the objects. and optic ataxia is problem using vision to guide to grasp objects.

for haring our auditory system will detect changes in the vibration of the air. It senses inteisity as loudness and freeqency as ptich, Our outer ear will direc the sound to the inner ear where it si tranduced into neural activity. . so the pinnae is the external ear. it will collect sound waves through the ridgges and valleys of the outer ear. it will also modify the sound that reaches the middle ear some frequenciees are enhacned and other are supressed. again so bascially the outer ear which is the pinnae which is full of grooves and valleys will collect the frequency and modify it and some of it can be supressed or haenhanced. the shape ofc the pinnae or the extrnal ear will provides cues about the direction and the dsitacne of the source o the sounf. so the sound will travvel to the mid ear and then inner.

againnn so basically the eaxterenal ear the pinane full of grooves and valleys will collec the sound andmodify it by either supressing or enhancing and it will also collect clues about th edirection of the sound and then send it throught the canal into the middle ear where it reaches thetympanic membrane. . the tymapnic membrane is like a seal at the end of the canal that ha slike a wall and also ossicles which are middel eaer muscles are connected to it. So the tempanic membrane is the eardrum. Tymapnic membrane at the back of the ear canal is the ear rum. and then sthe sound will travel to it where it will hit it and vibrate at the same frequency as the sound this will cause the osciles which are bones to move as well. so these oscciles will concfentrate and amplify the vibration and focus the pressure the the large tymapnic membrane to the small oval windown. agin so the sound eneters through the pinnae where it will then go into the ear canal and then hit the tymapnic membrane where it will then cause ossciles to vibrate to and ampliyf and concentrat ethe viration where it will then go towards the oval window of the inner ear. so the oval windiw is also a piece of membrane. so the soundw aves in thte the air hit tye thmapncica sues vibration of the same freuenct and then ossciles will move and then focus ehe pressure and sne di to thte large membrane to the smalll oval einwod. the amplifciation is needed for converitn vibrations in air into movments of fluid in the inner ear.

the amplification is needed for converting vibrations in the air itnot movments of the fluid in the inner ear. the middle is also equpied wihth the of volume control tha thhelps protect against damanging forces of loud noises. two musleces that protect thhe are the tenor tymapnic and thhe stapediu which attach to the end of the ossciles. the brainw ill signal thhe muscles to controuct wheren there is a loud sound and the cain of the sccicles will sitffen and reduce the effectiveness of the sound

The ossicles will amplify sound from the air filled middle ear to the fluid filled inner ear. To protect inner ear from damage of loud sounds there are the tensor tympani and stepdis that contract and stiffens th ossicles Cain. The final bone is the oval window which is amembran opening into the cochlea of the inner ear.

tSo it goes outer ear pinnae, ear canal, tymapnic membran, middle ear oscciles, then the muscles maybe tensory tympani and stapedis to protect against large sounds, then the oval membrane, into the cochlea.

the inner ear iwll turn vibrations from sound into neural acitvity of the fluid filled cochlea. it is like a small snail the size of the pea.

1. scala vestibuli 2. scala media 3. scala tympani. The middle one the scala media contains receptor systems call the organ of cort that converts vibrations into neural activity.

so thhe medial scala is between the vestilu and tampanu. the organ of corti has celsl. the orang of corti is closest to the tampni on e

the organ has three strucures the auditory cells which are he hair cells taht bridtged betwen the basicalr membrane and tectorial. so on the bottom is athe basilar memb ran on top is the tetectorial and in b etween is the hair cells sensory cells.

• outer ear , the pinnae will come in and will either amplify or dimish the amount of frequency that is going to enter into the innner , this is done thoruhg the grooves and the valleys that it has, then the ound is going to be transmitted into the ear cannal where the found and its frequency is tgoing to hit the tympanic membran or th e ear drum where it is going ot then cause the ossicles tat are attached to vibrate and amplify the sound so it can go into the innear ear where the inner ear has fluids. so it goes from the tympanic ear, ossicles, oval window, and then the choclea that has three parts, the scala vestibuli, the scala mediual, and the scala tympani. The scala medial has the organ of corti that will transbrine neural activity to the brain from the fre44quency. FSo then in

so the ochclea in the inner ear will recieve the vibrations of thte sound and turn it into neural actvity. the choclea has three paralel spiral cancals the scala vesibuli media and tymjpani. when there is a sound that is too loud the oscciles called the tenor tympani and the stapeiud. THe tenor tympani and stepdius. Tenor stapediu temapnu and stapedius.

The scala medial contains the receptor system called the organ of corti that will conver the vibrations into nerual activity. It has auditory sensory cells the hair cells that will bridge between the basilar membran and the tectorial membrane. the auditory sesnory cells the hair cells basilar and tectorial membran.

vibration enter the scala vestibuli, the upper fluid filled, then these waves will travel through the fluid and affect the basilar membran in the scala media. this rupple of fre44qnecy of the sound will cause vipation and on top of the basialr membrae are hair cells. On top of the hair cells are stereocillia.

so the hair basialr membrane will vibrate and then it will push the cair cells upward and the sterocilia wil bump the tectorial membran. and cause it to bend. The shotrter sterocillia ben ward the taller ones and stertches the tup link and this opens te gated ionchnanels on the sterocillia tips.

so once the fluid vibrates from the scala vestiubuli then to the scal media where the basila membrane will vibrate and cause the hair cells the adutiroy sensory cells and the sterocillia to bump and bend towards to the tescolian, testeculiar membran and then theat will cause neurotransmitters to release as the ben opends the ion channel and then the neurotransmitters will go attach to the nrve fibers that are at the base of the hair cells. There are three rows of outter hair cella dn one of inner hair cells that aagin have the sterocillia at tht eop. the overal procaess of the scala medial is to traansmform vibration into neural activity.

inner hair cells are afferent meaning they send signals from the ear to the brain. THe outer hair cells are efferent so from the brain to the ear. the inner afferent hair cells are the main sensory recepetors. inner hairs are the main sensory receptor that are aferent meeaning they send singla sfrom the ear to the brain and are 95% and the outere ears are efferent so fromt the brain to the ear which will lead to amplifyin g senstiry . and fin tune sounr

the neurotransmitters will go to th fibers of the vesibulochlore nerve. Vesibulocholear. Vesibulocholear.

differnent frequencies will repond to differnet part s fo the basilar membrans. SSo high frequences havae effect on narrow areas and low frequencies on large more wider flexible areas . so afferent ihc will ocnvety fromtion of sound percetion ot he brain and IFC efferents will allow to brain to control repsonivesnns of IGC>S

again so Innher hair cells will afrferent infromation and perception of sound to the brain and efferent inner hair cells will recieve infromation of the brain to the aear controlling IHC. and outer hair cells dont sendc info to the rain but they reciev einofmriaton from the brain to the aera modifying and controlling stifnes of the basialr membran.

soo from the beginning. There are sound wave or frequencies that will hti the external area pinnae where the grovvfe and aalleys have the ability to enhacne or d4eplete the sound freqnecu and also be used to locate spaital sound and then go into the e4ar canal where it will hit the tympanic mebrane or the ear drum whic intates the beginnign of the middle ear that consitutes of osccile bones that allow for the amplification of the frequency in order to prepare the arrival of the virbation to the inner ear through the oval wiindow which is another membran that allow the isnertion of vibration to the choclea wher ethe fluid vribations will enter the scala vestibuli and then the scala medial where there virbations will cause the basilar membran to move where the connection hair cells auditory sensory cells will cause the uprise of the sterocillia cells that will bend towards the reaction of the mvemnt hitting the tectonial membran to open chnnale ions allowing for potassium K+ and ca2+ due to the bending gof the sterocilliaw. Then this causes neurocal vesciles to release neurotransmitters that will then itneract with the ve4stibulochoclear nerve that will either send or receive infromation to the brain through the nerve fibers. Although there are two different types of hair cells inner which constitues 95% of the recpetors and aferent will send informaiton to the brain about sound perception and efferent innher hairs will reciev einfrmaiton controllin g the innher hair cells. Ther eis one row of hte innere hair clel and then there is the outer hair cells that contistues of three rows but afferent cells dont happe so no informaiton is beign sent to the brain but the brain will send ifmoriatno to the outer hair cells about stifffinign the basilar membrane. the higher frequencies will travel to the nor naroow stif parts of the choclear and the lower frequencies to the wider and more flecible areas of the choclear. The inner hair cells release glutamte to the brain and recieve aetylcholin back. and outer hair cells will release ach to the brain and recieve gaba back through efferef ibers.

so the inn hair cells wil release glutamate, to the the affreent to brain. I

Si inner hair cells release gluamate to the brian and receive acethylcholin to the inner hair clels

And other hair cells will send acetylcholing to the brain and recieve gaba.

so information from the vestibularchoclear fiber nerves will enter the brains tem at the nucli coclear nucli where some are termianted and processed where the ifnroamiton is then processd and the outpt from th ecochlear nucli will proejct to the superior olivar nculei.

so the nervge vesitobolcholear nerve will go to the right and the left go to the let and this is we=here omeinfromation is processed and other infromation is processd and then some of the fibers will cross over o the other side of the brain stem and synapse into the contralterla superior olivary nucleus.

so the nerve vstibulchcolear enter its own side of the cochlear nucli an some informaiton is process ed and some ifnromtion is terminatd . choclear nucli is in the brainstem. And then the fibers at the choclear nuclei fibers will switch over to the superior olviary nucelus. then the infromation. superior oivary nucleus. infromtion is profeccesed to the inferior colluculus.

nerve, choclear nucli, then the superior colicus ncuelus where the infromations witches, then the inferrior colluclus, then emdia geniculat enucleu, and then the audtory cortex.

so chilear nucli, superior olviary cnucleus, inferiorl collisulus, medial geniculate nculeu of the htalmus. hten the pimrary auditory cortex in the tempral lobes .

superiorl olviary nculeus then infeiror collulis then the medial geniculate. Medial genulate neucli then the audito cortex where. it is at the tempral lobes . WHere tone noises and pseech acitvate. it

so there is intratural intensity differenced IIDs which reults due to placemnt and characteristics of their pinnae intesity differences occur because on ear is pointed towards the sound of the sour and the other casta s ound hsadow. SO IIDs is whne one ear is more towards the sound and creates a dhowdow for th other ear. one ear will have a higher frequency sounds. IIDS is

ITDS is when one sound takes longer to reach the more distant ear. so IIDS is when shaodw is casted and ITDS is when they arrive at different times.

if sound is too loud it can destroy the hair cells and damage the choclear and missing its hair cells results in deafness. elecontr amd tje steprco;o can be flattened or crushed due to excessive noise exposure.

SUMMARY of 6

pinnae will collec thte sound waves and the grooves and the valleys and then it will wieht emaplify or deteone it and then it will also colelct spatial infromation about ewhere the sound is ocmingg tfrom and then thre frequency will go the otheear canal and then go to the teympa nic membrane

our sense of balan ce comes from the vesibular system is the samll strucuter that adjoin to the cochlea.