VISION 1 9 Questions Lecture 18 Perception objects in our environment emit or reflect energy that stimulate receptors on sensory neurons creating stimulus energy What does perception depend on think law of specific nerve energies 1 Type of receptors stimulated a Law of Specific Nerve Energies every stimulation of optic nerve is perceived as light ex Rub eyes and you will see flash of light 2 How many much is stimulated 3 Pattern of stimulations 4 Which neurons those sensory neurons project to Describe the general path that stimulus energy takes through our brain leading to conscious perception 1 Receptors on sensory neurons retinal photoreceptors 2 Nerve to CNS optic nerve 3 Thalamus lateral geniculate nucleus 4 Primary cortex visual cortex 1 striate cortex 5 Association cortex visual cortex 2 How does light enter the eye light photons enter through pupil Describe the path it takes through the cell layers of the retina and the path of signal transduction 2 options 1 Photoreceptos Bipolar cells Ganglion cells 2 Photoreceptors Horizontal cells bipolar cells amacrine cells ganglion cells Less cell connections better acuity sharpness Signal Transduction Transduction is the process of taking environmental and making it something brain can understand and receive in form of action potentials and neurotransmitters The sensory neurons contrain pigments which can change form when the absorb photons particles of light this aleration in pigment causes the firing of receptor cells AKA LIGHT ENERGY IS TRANSDUCED INTO ACTION POTENTIALS AND NEUROTRANS ARE RELEASED without light photoreceptor cells spontaneously fire inhibitory neurotrans which makes postsynaptic cell not able to fire With light neurotrans not released postsynaptic cell can fire excitatory neurotrans How are rods and cones similar and different On what point of the retina are cones most densely packed Rods Cones Respond in light Dim light Bright light Location periphery Center densely packed in fovea What type of vision Black and white Color Detailed images Fovea depression in retina where light hits With which types of cells do photoreceptors synapse Do they excite or inhibit those cells Photoreceptor cells synapse bipolar cells they inhibit them in dark and excite them in light On what is our perception of color based The wavelength in which the photons hit photoreceptors individual colors is based on relative rates of responding of three different subtypes of cones that respond to certain ranges of wavelengths VISION 2 7Questions Lecture 19 Describe the path of the optic nerve what and where do fibers cross and to what two areas do they project The axons of what type of cells make up the optic nerve and what is the result of the optic nerve passing through the retina The optic nerve is made up of the axons of ganglion cells the optic nerve carries info from eye to brain The optic nerves from the two eyes meet at the optic chiasm half of axons remain ipsilateral axons on temporal side and half become contralateral those on nasal side Info from right side of eye is processed by left hemisphere info from left side of eye is processed in the right hemisphere The result of the optic nerve passing through the retina is the creation of a blind spot which we usually don t notice b c of our binocular vision What type of ganglion cells that project to the lateral geniculate thalamus are important for distinguishing detail and which are more important for perceiving motion How else do these cell types differ 3 types of ganglion cells Parvocellular small receptive fields good for detail what Mangnocellular big receptive fields good for motion depth where Koniocellular diverse group with a variety of special functions What is V1 necessary for What is it not necessary for Primary visual cortex 1 striate cortex necessary for conscious perception of visual information individuals who are blind due to eye damage are able to engage in visual imagery Not necessary for blindsight can respond to some aspects of visual info Picture appears on screen blindsight is being able to reenact the exact expression even though blind Audition 9 Questions Lecture 20 Describe the path that sound takes through the ear at which point s does the sound travel as waves of air and where is it converted to waves through fluid Outer ear Pinna focus of sound waves Auditory Canal Tympanic membrane eardrum Middle ear Ossiles amplifies pressure of sound wave Inner ear oval window displaces fluid in cochlea cochlea Converted to waves through fluid in oval window cochlea basilar membrane in inner ear http www youtube com watch v PeTriGTENoc At what points would damage cause conductive versus nerve deafness Conductive deafness middle ear abnormalities Nerve Deafness Inner ear abnormalities What properties of sound do we perceive as pitch and loudness How are these attributes coded by activity of the auditory receptors Pitch low frequencies hair cells on top of basilar membrane fire to sound waves High frequencies hair cells on base of basilar membrane fire Frequency coding depends on size of sound waves Loudness is coded by amount of cells behaving in the same way at one given time Does the cortex receive contralateral or ipsilateral projection from the thalamus How is sound information processed in the cortex i e tonotopic map Cortex receives both contralateral and ipsilateral projections from the thalamus Organized by tones our perception of frequencies look at diagram of tonotopic map below Taste 7 Questions Lecture 21 Describe how chemoreceptors are organized on the tongue e g papilla Taste Papillae bits of tissue on tongue that are raised and contain taste buds Fungiform small back 2 3 of tongue Foliate medium size front 2 3 of songue and sides Circumvallate large very back of tongue and palate How do taste receptor cells code for the different primary tastes Different receptor cells signal different chemical stimuli Can be direct ionotropically Salty receptors depolarize with influx of Na or Sour depolarize with influx of H or can be Metabotropic sweet bitter stimuli hook onto receptors that induce second messenger which increases probability that receptor cells will fire What two nerves carry taste information to the brain Facial and glossopharyngeal nerves What is their first stop in the brainstem Nucleus of Solitary tract NTS in hindbrain Where do they go from there and do they go ipislaterally or contralaterally Some info goes ipsilaterally via the typical
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