Week of Notes (4-5-16 and 4-7-16)
Week of Notes (4-5-16 and 4-7-16) PSYCH 3240
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This 5 page Class Notes was uploaded by Lucy Stevens on Thursday April 7, 2016. The Class Notes belongs to PSYCH 3240 at Clemson University taught by Dr. Claudio Cantalupo in Spring 2016. Since its upload, it has received 25 views. For similar materials see PSYCH 3240 in Psychlogy at Clemson University.
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Date Created: 04/07/16
Chapter 9 Continued 4-6-16 *Make sure to know the picture of the auditory pathway Three Types of Binaural Cues 1. Phase Difference Cue 2. Intensity Difference Cue 3. Difference in Time of Arrival Cue Chapter 10-Vision Up to Page 321 Vision • Stimulus: visible light (form of electromagnetic energy)è its just a fraction of the electromagnetic spectrum • Why do we have eyes that can only see the visible light? o There is something special to this type of energy compared to the others. Thing like FM or AM waves tend to go around a lot of stuff because they are so huge, so they miss object sometimes. That would be bad for vision. The Eye • All eyes started out on their own. • Retina: the neural tissue and photoreceptors located on the inner surface of the posterior portion of the eye; very large and intricate neural network; scientists think of it as part of the nervous system that sort of came away to be able to capture stimulus quickly o Three layers 1. Photoreceptor Layer: cones and rods 2. Bipolar Layer: bipolar, horizontal, and amacrine cells 3. Ganglion Cell Layer: ganglion cells o Receptors: cones and rods; specialized cells that receive photons and transform that type of energy into a completely different signal o Horizontal Cells: neurons that connect the retina in the horizontal direction; on the photoreceptor side of the middle layer of the retina o Bipolar Cells: neurons that connect the retina in the vertical direction o Amacrine Cells: similar to horizontal cells; tend to connect synaptically bipolar cells and other neurons in the horizontal connection; on the ganglion side of the middle layer of the retina o Ganglion Cells: axons of these cells come out of the cell body and cluster together to form a very large cable that is visible and is called the optic nerve; quarter of an inch thick o Fovea: center of the retina; labeled at 0° o Blind Spot: area of the retina where there are no rods or cones; no stimulus can be detected if one falls in this area; all of the axons coming out of the ganglion have no choice but to leave the eye at the back; the vertebrate retina is backwards which causes the blind spot; a better idea would to have the photoreceptors facing the source of the stimulus *Long strand of protein that is joined with the vitamin derivative called retinal. ON single photon flying along can change the chemical connection between the vitamin and protein. Photons are changed into an electrochemical signal. *When sodium channels are open: the neuron is now activated and excited and membrane is depolarized causing the release of inhibitory neurotransmitter and inhibits activity of the bipolar and ganglion cells, which is why you see nothing. *When light is present, photons arrive and start knocking off retinal vitamins from the protein, which is the first step of reactions that results in the closing of the sodium channels. When the NA+ channels are closed, the neuron is inhibited and becomes hyperpolarized which releases less of the inhibitory neurotransmitter and the signal travels to the ganglion cells as the firing rate increases. • Rods: are in charge of our night vision; provide no experiences in differences in color, only in difference sin brightness; contain photo-pigment Rhodopsin, which is very sensitive to light; they work best in dim light; NOT found in the fovea • Cones; much fewer cones than rods; contain photo-pigment Iodopsin, which is much less sensitive to light and requires a lot of light; our day light vision; come in three different kinds of iodopsin allowing us to provide information on different wavelengths coming into the eye; RED (long wavelengths), BLUE (middle wavelengths), and GREEN (short wavelengths) • Cones and rods are wired differently to the retina • Receptive Field: area of the retina with a patch of receptors from which a ganglion cell receives input **Are rods and cones distributed evenly across the retina?? NO! Cones are mostly concentrated near the fovea. The further away from the fovea the less likely you will see a cone. There are virtually NO rods in the fovea. Outside of the fovea, the rods are everywhere. The fovea is basically the cone system. The rest of the retina is the rod center. • Cornea: membrane that is in the front of the eye; thickness and curvature is the most important lenses of the eye; accounts for the eye’s ability to go to the retina • Lens: important for our ability to maintain an object on focus; for near-vision; series of transparent, onion-layer layers; shape can be changed by contraction of the ciliary muscles *Cones are found tightly packed into the fovea. *Receptive Field: area of the retina from which a ganglion cell receives input; typically very small; affects the activity of the neuron *Ganglion cells in the fovea have much smaller receptive fields than in the rest of the eye. *Fovea has the highest visual acuity. *Highest Visual Acuity- ability to distinguish the details of a visual scene *You are able to see the small print in a book because the image falls into the fovea. *If all of retina had perfect resolution, what would happen? So much information would be produced, that we would have a hard time knowing which part of the environment to look at. We would need a much more powerful brain. *Visual Field: part of the environment that is registered in the retina; anything that you can see and anytime • Nasal Side • Temporal Side • Stimulus from left non-overlapping part of the visual field, the image will follow on the nasal side of the left eye and the temporal side of the right eye. • Stimulus from the right non-overlapping part of the visual field, the image will follow on the nasal side of the right eye and the temporal side of the right eye. Optic Chiasm: no complete mixing of the optic fibers; about half of the axons of the optic nerve pass over each other; part of the CNS Lateral Geniculate Nuclei (LGN): part of the thalamus that relays info to V1 Primary Visual Cortex (V1): part of the occipital lobe; contains first cortical neurons that follow stimulation of the retina Retinal Cortical Pathway: responsible for our conscious experience of seeing anything; not the only visual pathway in our brain Retinal Tectal Pathway: this other pathway; past the chiasm are fibers that go into the midbrain (Tectum) instead of to the thalamus; can experience blind sight; Binocular Field *Retinal Disparity: discrepancy in the location of an object’s image on the two retinas as a function of the objects distanceè detected by the visual cortex that helps with depth perception Color Vision: colors don’t actually exist; there is nothing absolute about color perception; provides a selective advantage Theories of Color Vision • Trichromatic Theory (von Helmholtz and Young) o All colors are the result of the processing of three “pure” colors: red, green, blue, each one detected by a specific receptor o Problem: yellow also appears to observe as “pure” color o Most people come up with 4 colors that they feel are “pure” to them, but there is no cone for yellow • Opponent Process Theory (Hering) o Explains color vision in terms of opposing processes in two specific receptors o Red goes with green and blue goes with yellow o Receptor for red and green: photochemical § Showing different lights have different effects o Receptor for yellow and blue: photochemical § If you shine yellow it should break down § If you shine blue light, that will build up the photochemical o Explains complementary colors and negative color aftereffect.
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