Psc 131_ test 1-1.txt

Light is a form of electromagnetic radiation, it differs from other electromagnetic radiation in wavelength

Between 400 and 700 nanometers

• Violet: 400
• Blue: 500
• Green/yellow: 600
• Red: 700

Violet (short)--------->red (long)

• 1. Absorption
• 2. Refraction (photon's course is bent)
• 3. Reflected (a certain % of photons is reflected depending on thickness of object)

No, wavelengths give off color but there is not color in light

It is created in our brain

Shorter wavelengths get refracted the most leading to long wavelengths

They bring parallel light waves into focus

The greater the curvature of the lens, the more refraction on the light

Floaters are dead cells floating in the vitreous

The cornea refracts light and it is located in front of the pupil/iris

A small area in the retina of the eyes where acuity is the highest.

The iris can change diameter to make the pupil bigger or smaller; this allows for different amounts of light to enter the eye

The parasympatetic reduces pupil size and the sympatetic increases pupil size

Autonomic N.S. is involed with arousal

The retina is located all around the back of the eye and it turns light it to neurological information that is sent to the brajn

Our vision is focused on objects that are far away

There is more curvature and our vision is focused on objects near by

Myopia is when we are nearsighted; we need a negative lens to spread out light before it hits our internal lens

Hyperopia is when we are farsighted and need a positive lens to focus light a little more before our internal lens

When your eyes have a different radius of curvature so they cant focus a point

Presbyopia is due to aging; it is when the pupils shrink and our ability to accomodate reduces, making is hard to focus on near things

In order from the vitreous to the back of the eye:

• Ganglian cells
• Amacrine cells
• Bipolar cells
• Horizontal cells
• Rods & Cones

They send informarion to the optic nerve

They connect ganglian cells to the rods and cones

They are the photoreceptors in the back of the retina that absorb light

Discs od photo-pigment are fond in cones and rods.

They absorb photons of light and which break up pigment molecules, becoming hyper polorized

After a photo-pigment is broken down, transduction occurs which is changing a physical stimulus into a neuro representation of that stimulus

The conversion of physical energy into neural activity

Bleaching is when a photon has been absorbed by a molecule of photopigment.

The molecule is broken down and the photo receptor is less sensative because the pigment cant absorb light any longer

The reduction in photoreceptor sensitivity following light exposure.

The exposure to light redudes light absorbtion and it takes a while for thr photopigments tp reform

Dark adaptation is when, you return to a dark area and photopigments slowly reform, increasing sensitivity to light.

Rods are sensative to low light and black & white colors.

They are found all around the retina except the fovea

Cones are sensative to high light and color.

They can be found abundantly in the fovea.

Our blind spot is where the optic nerve is located. But we can't point it out because our brain fills it in slowly according to what is around us

We dont see our retinal vasculature because although photons are absorbed by blood vessels, enough light reaches sensitive light receptors and because they remain statonary.

We can see floaters becuase their constant movement does not let our photoreceptors to adapt

they both have same amount of sensitivity...the cone that absorbs ligth directly is constantly in bleach so its sensitivity goes down and the cone with the vessel in front of it doesnt get as much light because photons get absorbed by the blood.

Ganglian cells

Tectopulvinar and geniculostraite

Optic fibers go straight from the eye and cross at the optic chiasm. Then from there they go to the SUPERIOR COLLICULUS and after to the PULVINAR NUCLEUS and ending at the occipital lobe

Optic fibers head to the LGN lateral geniculate nucleus then the occipital lobe

The naisal hemiretina and the temperal hemiratina.

Fibers that end up on the same side of the brain are ipsy-lateral. Aka temperal hemiretinal

Fibers that end up on the opposite side of our brain are contra-lateral. Aka naisal hemiretinal

Things that land on the right visual field of both eyes end up on the right side of the brain, and vice versa

After the occipital lobe information is sent to the temperal lobe

Cortical magnification is the fact that more cortex is devoted to processing central as compared to peripherap vision.

The dorsal (top back) and ventral (front) pathways

The dorsal pathway leads to the parietal lobe and it is related to the "how" of vision; as in how we interact with what we see

The ventral pathway leads to the temporal lobe and it is related to the "what" of vision; as in what objects are qnd how we recognize them

The ganglian cells tell the brain that rods and cones are getting light

A receptive field is a region of photoreceptors a ganglion cell gets inhibited or exited by.

When the receptive field has either a positive or negative stimulus, signals are sent to the brain

The ganglion cells sends no signal because it stays in its resting phase

Yes, when receptive fields overlap there can be neural convergence and divergence

Neural convergence is when many cones and rods influence one ganglion cells

Neural divergence is when one cone or rod can influence many ganglion cells

A simple cell receptive field is a visual cell that has only one area that exites the cell and the area around it inhibits the cell.

A complex cell receptive has an area that is stimulated by light coming at a certain orientation.

A hypercomplex receptive field is an area where the neurons only respond to a certain type of movements

A parvocellular system has smaller rdceptive fields and sustains responses to color

A magnocellular system has big receptive fields and slow responses to moving objects

Spacial summation is adding the responses from two areas in space

Lateral inhibition is when surrounding inhibitory rods & cones cancel an exitatory response

Parvo ganglion cells lead to the parvo lateral geniculous nucleus through 3 visual pathways (3rd one is for color) and into the temporal lobe via ventral pathway

Magno ganglion cells lead to the magno lateral geniculous nucleus through 3visual pathways and then a movement pathway into the parietal lobe via dorsal pathway

Our perception of a center region is affected by the surroundings

Our perception is influenced by how much light is coming at us from an object

Lightness constancy states that the lightness of an object is based on the % of light reflected by that object

Constancy is the tendancy to percieve constant properties of objects.

• There is:
• Light constancy
• Size constancy
• Shape constancy

The mach bands tell us that we percive thongs to be light and darker along the edges of an object based on its surroundings

The hermann grid is a grid of squares that make us percive shadows at intersections when fixated on a point. It teaches us that the areas that dont have our focus are percive to have a shadown because there is lateral inhibition occuriing on the receptive fields.

The alleys between two squares have an exitatory response in the receptive field so they appear to have light

• Snellen acuity
• Vernier acuity
• Stereo qcuity

Snellen acuity is the ability to see fine details

Vernier acuity is being able to detect the offset of two objects

Stereo acuity is being able to tell the difference in location of an object, in our eyes

Fourier analysis (decomposition) is taking a square wave/complex wave and breaking it down to multiple simple waves like sine waves

The contrast sensitivity function tells us how sensative we are to various frequencies (waves lengths) of visual stimulous

Spacial frequency Is trying to see how many frequencies can fit into a dregree of vision

To see a certain spacial frequency, you need a level of contrast

Big cell receptors respond to simple parts od an object, small cells respond to details of an object

Fog scaters light

Your contrast sensitivity is reduced

When you are staring at a square wave frequency for too long, you loss sensitivity for multiple frequencies

The trichromacy theory states that by mixing BLUE RED &GREEN you could create any color; simply tweeking the amounts you mix

Pigments absorb most light so by mixing pigments you subtract the amount of light you can see

Becuase color is a psychological variable, the only way to obtain white is by mixing light

That there was three color receptors in the retina

The opponent process theory states that there are four primary colors:

Red, blue, green, and yellow

It also states that each color has an opposite which cant be experienced at the same time:

• Red-green
• Blue-yellow
• Black-white

The neuron sensitive to that color would be beyond its resting phase and would be very sensitive to its color opponent (color opponent afterimage)

It showed that every cone haa one of the 3 peek absorbtion. This proved the trichromacy theory

It means that the color matches people can is no like normal people

They see no difference between red orange and yellow