Psych 3313 Week 7 Notes
Psych 3313 Week 7 Notes PSYCH 3313
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This 12 page Class Notes was uploaded by Casey Kaiser on Sunday October 9, 2016. The Class Notes belongs to PSYCH 3313 at Ohio State University taught by Dr. Supe in Winter2015. Since its upload, it has received 4 views.
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Date Created: 10/09/16
Psych 3313 Behavioral Neuroscience 10/3 Vision Off-Center Ganglion cell, surrounding area is excitatory Center Ganglion cell, center is excitatory Lateral Inhibition Horizontal cells inhibit activity of neighboring bipolar cells Contrast enhancement helps us see edges and border o Completely in the dark the cell is at a baseline level of activity o In an on-center cell, when the surround hits the light-dark border more starts to happen o D on this graph is the most response we get, the center is across the light-dark border Herman Grid Illusion and Lateral Inhibition Ganglion Cells They don’t care about the amount of light just where the light changes Due to the antagonistic center surround, these cells are contrast detectors Three types of ganglion cells P-type o About 90% of our ganglion cells o Small size and small receptive cells o Receive input from midget bipolar cells o Involved in visual acuity and detail, color, and shape processing, bad at timing M-type o 5% of ganglion cells, larger receptive field o Involved in motion processing, good at timing but bad at spatial processing (details) o Receive input from diffuse bipolar cells Bipolar cell will depolarize in the light Ganglion cells will be where action potentials will start Visual Fields A lot of overlap in the visual fields from left to right There are roughly the left and right visual fields o The left eye is about numbers 1-8 o The right eye is about 2-9 o A lot of overlap A visual field is part of the environment that registers on the retina Right VF processed in left hemisphere Left VF processed in right hemisphere NOT LEFT EYE TO RIGHT HEMISPHERE LEFT VISUAL FIELD**** Nasal portion of your view goes contralateral, temporal view of each eye stays ipsilateral Our center field of view - foveal vision- takes up almost 50% of the signals Optic Nerves Ganglion cell axons bundled together and exit each eye through the optic disc About 50% of fibers cross over at the optic chiasm Optic Nerve Targets Suprachiasmatic Nucleus (SCN) o Located in the hypothalamus o Regulates the sleep/wake cycle o Small number of retinal axons Superior Colliculus o Located in the midbrain o Guides head and eye movements o ~10% of retinal axons Lateral Geniculate Nucleus (LGN) o Located in the thalamus o Projects to primary visual cortex, visual perception o ~90% of retinal axons Pathways to the brain Right and left visual field Optic nerve to optic chiasm to optic tract Most to the LGN and thalamus Not as many to the superior colliculus and other secondary midbrain nuclei Optic radiations to primary visual cortex Secondary visual cortices Pathway Optic nerve Through optic chiasm To optic tract to LGN in hypothalamus Etc Organization of LGN Magnocellular o Large cells, layers 1 and 2 o Get input from m ganglion cells - info from a lot of rods o Respond best to large, fast mocing objects Parvocellular o Smaller cells, layers 3-6 o Receive input from p ganglion cells - info from cones o Respond best to fine spatial details of stationary objects Input from each eye is separate Geniculate = bended knee - shows the bent shape of the LGN Input from V1 allows us to filter what to pay attention to Primary Visual cortex Has many different names that it can be called o V1, striate cortex, Brodmanns area 17, etc.. Major transformation of visual info takes place here o About 200 million cells here., o The input will stretch from "donut shape" to stripes or lines Lines are the preferred stimulus of cells in V1 Organization of V1 Topographical mapping o Locations on the retina and LGN correspond to locations in V1 - visual field will correspond to brain space o Foveal Magnification - we just bring things into our point of view to see it, rather than strain the peripheral Simple Cortical Cells Receptive fields maintain antagonistic center surround, produced by combining outputs of LGN cells o The shape is elongated, like a stretched donut o The vertical line produces the most stimulation Many action potentials How Striate Cortex cells get their orientation tuning The lining up of ganglion cells is how they get their preference of lines Complex cortical cells Larger receptive fields With these, vertical lines no matter where they are on the cell will have a lot of activity No inhibitory region on these complex cells This shows preferred stimulus size and orientation but not a preferred location in the visual field How the visual cortex is organized Orientation column - responds to lines of a single angle for single eye o Made of simple cortical cells Ocular dominance cells - responds to input from either the left of right eye but not both, preferred orientation changes Movement - complex cells Create a theoretical model of organization called a hypercolumn Thousands of things that correspond to the visual field Beyond V1 There is a split in processing Aka secondary visual cortex All specialized to specific features Consists of 2 dozen distinct areas o Adding features as we go What and Where pathways Dorsal stream - up toward parietal lobe but some structures in temporal lobe o Where stream Ventral stream - down toward temporal lobe o What stream Dorsal Stream Magnocellular Specialized for movement, locating objects, and visual control of skilled actions Better to think of it as a "how" stream, we can use this stream to determine how to interact with the object Akinetopsia - rare disorder of motion blindness that is caused by damage at the occipito-parietal junction o Instead of seeing life as a smooth movie, you would see it as a series of still images- cannot perceive motion Ventral stream Parvocellular Responds to shapes and colors Associated with storage of long-term memory o Prosopagnosia - rare disorder of face blindness caused by damage at the fusiform face area within temporal lobe The fusiform face area - responds to faces more than anything else The parahippocampal place area - responds to buildings and places more than anything else The extrastriate body area - responds to body parts like noses more than anything else Visual perception of spatial frequencies We can vary the contrast We can vary the frequencies o Use these to determine when we can tell a difference or see a uniform shade of grey Color perception depends on context Color Is a property of us not a property of the object Two main theories of color vision Trichromatic theory of color vision o Was generated before we knew we had three different cones that responded to different kinds of light o States that we have color vision based on a combo of activity in short, medium, or long sensitive cones Opponent Process theory to color vision o Color vision is based on exciting one color and inhibiting its opposite o Supported by complimentary colors and afterimaging effects A combined theory o We have cones that are sensitive o We also have blue-yellow, red-green opponent cells 10/5 Color Coding theories Trichromatic theory - explains the functions of cones in the retina Opponent process theory - explains better beyond the retina Color Blindness - males are far more likely to show it than females Dichromacy - 2 cone photopigments Monochromacy - person has one or no cones (more rare) o Closer to seeing the world in shades of grey Tetrachromacy - 4 cone photopigments (more females) o Related to x inactivation of some sort Development of Contrast Sensitivity Newborn vision seems to be pretty bad o Infants see less fine detail at a distance, they have very low acuity and clarity o Show a strong preference for things that are high contrast and colorful objects o Also more drawn to facial stimuli Perception of Depth Monocular cues - only need one eye for, use all of these things to figure out how far an object is from us o Perspective o Texture and shading o Comparison of size of familiar objects Binocular cues - need both eyes o Retinal disparity o Disparity-selective cells Hierarchical Processing - theory with vision that we take the small features to make lines, then make angles, then make shapes, etc.. Building up from the most simple to the most complex Feature detectors respond to particular features, angles, lines, movement, etc. Ex: grandmother cell Jennifer Aniston Cell, could there be a cell that is specific to something in your world? o Possible that it was just for something meaningful to that person Eye Shape influences visual quality Normal 20-20 vision, info is projected onto the fovea Myopia (nearsightedness) - image is projected in front of the fovea Hyperopia (farsightedness) - image is projected behind the fovea Astigmatism is a problem with the curvature of the eye Age Related Problems Presbyopia (hardening and yellowing of the lens, macular degeneration) Blindsight - phenomenon Visual Agnosias Akinetopsia - movement blindness Prosopagnosia - difficulty recognizing faces How do we take something from the environment and translate it into something our brain understands? Transduction - converting external energy or substance into neural activity Sensory adaptation - activation is greatest when we first detect a stimulus Top-down processing Expectations, biases, life experiences, memories will guide our senses and tell us what to focus on Bottom-up processing Info and details are coming in and influencing our thoughts Sound as a stimulus Sound results from collision of molecules - typically air molecules but can be water molecules Amplitude - intensity of sound wave (loudness is how we perceive the intensity) Frequency - wavelength of a sound wave - gives us info about the pitch Measured in Hertz (Hz) Single frequency = pure tone, not the most pleasant for us Multiple frequencies (timbre vs noise) Human range that we can hear - 20-20,000 Hz Piano Range - 27-4,000 Hz Ultrasound and Infra Sound Ultrasound - above the range of human hearing (higher than 20,000) o Used to make images, in diagnoses typically o Bats perceive this and use this ultrasound Infrasound - below range of human hearing o Associated with atmospheric events o Used by many animals - how animals can show when weather will be changing they run away o People looking at using this as a weapon against people (cause dizziness, nausea, bowel movements) Crowd control weapon There is a lot of variation in individuals with what they can and cannot hear As people age, the maximal frequency they can detect will decline There are also environmental and life experiences that can influence the ability to perceive sound Structures of the ear Outer ear o Ear canal o Pinna Middle ear o Rest of cannal o Ossicles Inner ear o Everything else Outer ear Pinna - fleshy bit, outside of head o Purpose is to collect, focus, and localize sound o Cupping your ear to hear better is exaggerating your pinna o Signals emotion in animals (horses, dogs, etc..) The Auditory Canal - tube-shaped opening to middle ear Middle ear Two different membranes The Tympanic membrane - ear drum The oval window - leads to the cochlea The ossicles - bones that amplify the vibrations and transfer from air to fluid o The Malleus (hammer) o Incus (anvil) o Stapes (stirrup) The Inner Ear Cochlea - fluid filled chamber that responds to the amplified vibration o Snail shell shaped structure o The oval window is the starting point of the cochlea, this membrane is pushed in by vibrations and bones that will create waves in the cochlea o The round window relieves pressure in the cochlea o Contains three fluid filled canals Vestibular canal (perilymph) Tympanic canal (perilymph) Cochlear Duct (really interested in this ) (the fluid here is endolymph, higher concentration of potassium and low concentration of sodium) o Inside the cochlear duct is the organ of corti Organ of Corti Where we have transduction Contains hair cells - inner hair cells act as receptor for auditory transduction Sits on the basilar membrane Picture seaweed in the ocean - they sway back and forth in a way with the movement of fluid in the ear Sound Transduction Ossicles transfer vibrations from tympanic membrane to the oval window Movement of oval window… Hair cells Two types o Inner hair cells, what we are interested in for hearing o 95% of hair cells o Organized in one row o Outer hair cells Active, move in response to sound and amplify travelling wave Only 5% of hair cells How do we turn transduction into neural signals Resting membrane potential is -70 mV Mechanically gated channels - that the stereocilia open with the waves of the fluid o Connected to a potassium channel (not sodium) Opening the channel leads to depolarization and glutamate release The more vibrating there is the further they are pushed and more channels open, leading to more potassium and more depolarization and higher rate of action potential How does a cochlear implant work? Sound enters a microphone and travels to a sound processor. The digital information is transmitted electrically and electrodes stimulate the auditory nerve in order to send info to the brain Because in deafness, the inner ear is damaged, the inner hair cells are damaged or even lost so we can still detect that sound is happening but the signals cannot be transmitted electrically to the auditory nerve Hair cells -> spiral ganglia neurons -> ***important slide shows how info travels to the brain** Making table of thalamic neuclei and the senses that go with them will help Something processed in the ear will be processed on the right side of the brain 10/7 Primary Auditory Cortex In the temporal lobe Dorsal stream process the where of sound Ventral stream process the what of sound Auditory Perception How do we tell what the pitch is o Due to frequency, intensity, and context Frequency theory of pitch perception o If you play a sound at 440 Hz there will be a group of neurons firing at 440 fires per second Place theory o High pitch - proximal end of cochlea (near oval window) o Low pitch - distal end of cochlea (near center of the coil) Frequency-place theory o Frequency works up to 4 kHz (400 per second) o Place theory after that Loudness perception Anything about 120 decibels causes us pain At the very low and very high ends of hearing we need a much more intense stimulus to perceive it The stimulus of normal human speech is the "sweet spot" How we perceive loudness depends on the frequency - loudness contours Screaming in general is the frequency that we are designed to capture Localization of sound Air molecules of sound will arrive in our ears at different times with different intensities The Pinna is important for localizing sound We have Binaural cues (both ears) And Monaural cues (one ear) o Vertical time and intensity of sound at each ear is analyzed by the superior olive (in the brain stem) When sound is directly in front of you timing and intensity will be the same Off to the side, one side gets info sooner so we will be biased toward orienting toward that side Hearing Disorders Age-related hearing loss o Poor circulation to the inner ear, exposure to loud noise, hair cell damage Damage to outer or middle ear o Conduction loss due to wax build up, infection, or otosclerosis o Treated with hearing aids Damage to inner ear, auditory pathways, or auditory cortex o Treated with cochlear prosthetics, but varies on a case by case basis Cut out balance from study guide also cut smell and taste Sensation of Touch Light touch Deep pressure Vibration Stretch Hotness Coldness Chemical pain Mechanical injury pain The organ of touch - skin The largest organ of your body! Hair skin and glabrous skin (hairless) Three layers to skin o Outermost - epidermis o Dermis - middle layer - most sensation area o Subcutaneous layer - innermost - mostly fat and connective tissue Your skin is a lot of bacteria too Touch receptors - mechanoreceptors Respond to actual mechanical displacement of the skin in order to have a response Temp receptors - thermoreceptors Mechanoreceptor overview Meissner's Corpuscles Pacinian Corpuscles Merkel's Disks Ruffini's Endings Free Nerve Endings Each of these is a channel that respond to movement When they respond to a stimulus they open sodium channels, depolarize the cell, and action potential occur Encapsulated (think of it like in a water balloon) Receptors - Meissner's corpuscles, Pacinian corpuscles Nonencapsulated - riffini organ, merkel's disk Varying receptive fields Smaller receptive field - better at determining the stimuli o Merkel's Disk, Meisner's corpuscles Larger receptive field - not as useful for discrimination of touch detail o Pacinian corpuscles, ruffinis ending Relative Sensitivity The two point discrimination test Two poking points on a device that you can change the distance between Put it on different parts of the body and ask "do you feel two or one points" Depending on the receptive field (large or small) you will perceive it differently Index finger is very sensitive - good at determining touch Forearm, back / torso, calf - not as good at determining touch What explains this? The overall receptor density Type of receptors - there is a higher proportion of smaller receptive fields in the fingers and lips etc.. Adaptation of mechanoreceptors Refers to the length of time receptor will continue to respond to unchanging stimulus Grouped as fast or slow o Fast adaptation - Meissner's corpuscle and Pacinian corpuscles o Slow adaptation - Merkel's disk and Ruffini's endings Free nerve endings - not encapsulated, don’t really adapt because they are associated with pain Touch and Thermoreceptors Some free nerve endings act as thermoreceptors There are separate ones for hot and cold Pain receptors are recruited for extreme temperatures There are two main types of axons here A types and C type All A types are myelinated, the C type is unmyelinated o So A will be faster than C ALWAYS There is a size difference in the A subtypes o Aa (alpha-alpha) - largest, feedback from muscle fibers o Ab (alpha-beta) - a little smaller, mechanoreceptors in skin o Ad (alpha-delta) - smaller, pain, temperature, free nerve endings (stubbed toe first sharp pain carried here) o C - smaller, pain and temp free nerve endings but slower transmission (dull ache pain after stubbed toe carried here) Afferent Projections to the CNS Dermatomes - areas of skin served by dorsal roots Pathways Mechanoreceptors bundle together to the dorsal column, that will synapse in dorsal horn and take pathway up dorsa column, that will travel into the Medulla, then follow medial lemniscus to the VP nuclues of thalamus, and lead to the parietal lobe where touch is centralized Primary somatosensory cortex, there are specializations across this area Area 1- texture of object Area 2- how big the object is and is it moving Area 3- associated with objects that move Area 3b - light touch, size, shape and texture Touch can change in the brain Great example of plasticity Loss of input stimulates reorganization o Areas of the brain that no longer have a limb to associate with will reorganize to other parts and connections will change in an adjustment Think about musical training in humans - areas in the brain associated with needed touch (like left hand on a ukulele played) will be larger than those that do not need to be as aware of touch (right hand) Learning to read braille Increased use of thumbs in the youth - leads to higher detail and use, if you were to look at a generational difference the younger generation will have a more elaborate representation in the brain than an 80 year old Cortical Reorganization following amputation Phantom limb feeling After amputations you still have the parts of the brain that were associated with that limb, but over time that area will reorganize to associate with the adjacent limbs - because the brain does not have that limb to represent anymore it changes to help other parts of the body o Using mirror therapy to help alleviate bad feelings of phantom limb phenomena Pain It is important It helps to tell us a lot of things Emotional, cultural, social components to experiencing pain Receptors for pain are called nociceptors Respond to many different things o Mechanical injury, extreme temperatures, and certain chemicals Acending pain pathways Nociceptors come in through dorsal root, cross over in spinal chord and go up to the thalamus, can go to the somatosensory cortex (sensation of pain) or anterior cingulate cortex (emotional aspect of pain) Afferent pain fiber use Glutamate or substance P Different nerves used for different pains in the body Descending messages can influence pain Come from thalamus, hypothalamus, amygdala, etc.. To the pariaqueductal gray - to the raphne nuclei To dorsal horn The pariaqueductal gray has a lot of opiate receptors If we stimulate this area it can reduce pain
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