Biopsychology Week 4 Notes
Biopsychology Week 4 Notes 41363
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This 3 page Class Notes was uploaded by Jennifer Wagner on Monday September 26, 2016. The Class Notes belongs to 41363 at Kent State University taught by Dr. Douglas L. Delahanty in Fall 2016. Since its upload, it has received 9 views. For similar materials see Biopsychology in Psychology at Kent State University.
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Date Created: 09/26/16
Physiological Psychology 41363 Outline 4 I. Vision and Perception a. Sensory transduction: the process by which sensory stimuli are transduced into receptor potential b. Sensory receptor: a specialized neuron that detects a particular stimuli II. Anatomy of the eye—help with eye movements: vergence: eyes move together; saccadic: eye movements that your eyes normally make from point of focus to point of focus as fast as possible. Evolutionary relevant, very jerky; Pursuit: can slowly follow movement A. Sclera—white part, skin, outer casing of the eyeball. Sensitive. Contains vitreous humor (liquid inside) B. Cornea—transparent shield. First point of focus, barely dials in, NOT focused in great detail. Bends and refracts light. C. Pupil—hole into the eye, surrounded by muscle (iris) D. Iris—muscle. Controls amount of light that can come into the eye. As you get older, gets worn out, difficult to adjust to light E. Lens—fine tuning and fine focus. Cataracts is the clouding of the lens. F. Retina—back of the eye. Transduction occurs here. How you go from a ray of light to the action potentials. If focusing too soon, near sighted, focused too late, far sighted. 1. First layer ganglion cells. Transparent, light passes. Neurons whose axons come together to make the optic nerve. Going further into the brain. (Back of the eye). 2. Second layer 3 types of interneuron cells a. amacrine—passing info perpendicularly. Good at perceiving edges with horizontal cells. b. horizontal cells—integrate all of the info in photoreceptors with amacrine cells. c. bipolar cells—connects and passes info along the path 3. Third layer photoreceptors duplexity theory. Doesn’t do anything until it hits this layer. a. rods responsible for vision in dim light: more sensitive: however, lack detail and color. First discovered when studying nocturnal animals who do not need to worry about seeing color. Sensitive to low intensity light. 120 million rods. High convergence: hundreds of cells down to one. b. cones vision in bright light finedetailed color. Maximally sensitive to one of three different wavelengths of light and hence encodes color vision. 6 million cones. Low convergence, close to 1 to 1 ratio between cone and ganglion, so precision and clearer images. G. Fovea high acuity vision. Indentation; area of highest visual acuity. Made up entirely of cones. Takes up 25% of the space used in the brain allocated for vision. No diluting of the lights, cells pulled out to the side so light directly hits the fovea. H. Optic nerve blind spot; optic disk I. Optic chiasma—crossover of axons carrying information. Vision is a contralateral sense based on field of vision (not by each eye). J. Lateral geniculate nucleus and then primary visual cortex—first synapse is on the lateral geniculate nucleus in the thalamus. First time light synapses. Very simple pathway. Retna, geniculate, striate (pathway). Geniculate nucleus has 6 layers of cells; inner two layers oldest evolutionary layers. Magnocellular layer: perception of form, movement, depth, and small differences in brightness. Need to know most basic human needs for survival. Outer 4 layers developed later, focus on fine detail, and color. V. How does light get transformed into neural signals? A. occurs in the photoreceptors: vision largely inhibitory process. Lamella: layer consists of photo pigments made up of other constituents. Rhodopsin: opsin found in rods. Light hits them and they bleach, retinal and opsin are separated. Sodium is coming in and needs energy. In dark, spending energy to keep receptors open. Sodium channels close when opsin and retinal split which closes the channel. Cell no longer depolarizing; it hyperpolarizes (gets less and less positive) so stops releasing glutamate. Bipolar and photoreceptor cells do not fire action potentials but release NTs on the ganglion cells which depolarizes the ganglion cells which are able to fire action potentials. Opsin and retinal join together to form a photo pigment. Constantly releasing glutamate (excitatory), inhibiting bipolar cell because vision is different, inhibitory process even though glutamate is typically excitatory. B. rods contain rhodopsin made up of opsin and retinal C. cones contain iodopsin (3 types) and photopsin VI. Seeing edges A. Mach bands lateral inhibition. Show perceptually, see at more distinct level than what actually exists. B. Ganglion cells, lateral geniculate cells, and the lower layer of visual cortex cells are oncenter and offcenter cells most responsive to circular or curved edges C. Rest of visual cortex responds to straight edges 1. simple cells respond best to bars—lines in certain orientation. Cants move or inhibit it. must be in particular orientation and position 2. complex cells particular orientation but not position. Can move around but not pivot. 3. Spatialfrequency theory cells respond even more to sine wave gratings then to straight edges. Combine different gratings and come up to something closer to what we actually see.
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