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PSY290 February 12.dopsy290 feb 12cx

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Junchul Kim

PSY290 February 12, 2013 SENSORY SYSTEMS How capture environmental stimuli and convert to ap signal travel to brain understand meaning of environmental stimuli 4 senses, bc vision is covered in psy280, chapter 6 not covered 5 classic senses Today - Shared mechanisms of all the different sensations general principla governeing all 5 sensroy pathways What is senstation - Env stimuu phsy or chemic tranfromed into neual signal nerve system understand and when received by cns, lots of neural processing to provide meaning to those env stimuli to generate proper behavior output Sensation vs eprceptioon - Sen detecting - Perception is understading the stimulus Three steps - Env stimuli captured by specialized cells and once stimuli captured by receptor cells conv to ap propagate along axon till arrive at cns Step 1 - Look at sensory organ find specialized cell or structure that captures env stimuli all different shapes - Ear hair cells that capture sound signal all dif structure and specialized for all difernt sensory system specific stimuli - Specilised strucuture and function - Big difference between somat and other receptors - Somat – what capture env stimuli is not cell body but nerve ending, cell body is located far from skin - But tast smell hearin and vision they are cell body close strucutrer that provide capturing - This capture signal is transformed into ap and travel along axon to brain Step 2 - Mechanism underlying trans process – transformed through ap is ion channel must introduce change in membrane potential – psp release of nt’s, nt mole bound by receptor moleculer io or met resukt in change in membrane potential – close to threshold trigger ap in psneuron - If above or close to threshold trigger ap and go to cns through spinal cord - What is happening in sensory receptor cells is not all or none event – membrane protenital cell is grade trigger larger change in receptor cells or axon terminals in case of somato Step 3 - After generate ap travel to dif area of brain depending on modality and diff senroy modality take different path - Tocuh and pain travel different paths - Taste along different paths to sensory cortex - Specialized distint neural pathweay carry sensory signal - This one is somato – receptors in skin and gen ap – ap travel along axon to spinal cord to brain stem to thalamus to cortex Sensory cortex - Not good understanding - Know how sweet trigger ap and travel to brain – not how at brain complex senroy signal trigger sensation - Mysterious part is perception - Different cortical neurons are thought to be involved in perception process and process in hierarchal levels - Sensory signal at thalamus and go to sensory cortex primary they receive imput and information is process there and sent to secondary sensory cortex and receive mainly from primary and intra sensory processes a lot of infoamauin echancged and ass cortex binds features and all different features are bound together to understand what we see - All modalities glued together to generate perception - Perception controlled by neurons in ass cortex Sensory systems - Neurons recept ot thalmsus to cortexes - Type of information flow from one level to another - Happening in the brain not like this is certain degree of uni firectional flow but lot of change Organtion current model - Already exchanging information between strucutures - Level a lot of infor exchange - Neural signal flow along different pathway - Catch by receptor and to thalamus may skip primary and go to secondary - And same sensorysignal diverge to 2 signals - Level of specificity and complexity increase as go up - Complextity increase - Receptor – info exchange is minimal in ass it is high Three major steps - Env stim captured specialized cells and converted to ap spike and ap passed to cns along different pathway - All sensory pathways share three steps Hearing - Hear sound sound captured by cells in ear in innere ear strcutre and captured signals to ap and to brain audiotry pathway ear to auditory cortex Sound stimuli - What sound is - And how body structure evolved to accomadte this neural processing What is sound - Vibration of air – and three properties - Different amp – loudness - Dif freq – pitch - Complexity – timbre – simple or mixture of freq and amp Hearing - What we hear are mixture sound waves and ear distinguish indi sounds to understand meaning - How they are captured by streucture in ear Anatomy - 3 main parts - Outer middle and inner - Yellow color is outer – to capture sound wave more efficenlty to ear canal to tympanic membrane – collecting sound wave - When air vibrations arrive at tymp memebranic make it vibrate and those vibrations transform air vibration to next level transformation by structure in middle ear and purple thing is middle – bwteeen inner and outer ear - Ear drum and vibrate that vibration trans to bone strreucure series in middle ear - Ossicles – bony strcuutres – malleus incus and stapes - Roles of connective bone structure is to amplify sound vibratiuon delivered to tymp membrane - Design amplify air vibration by 20times - Deliver to oval window – tiny hole inner ear structure Cochlea - Important strcuure for sound capturing – transformation process in inner ear strucuture - Made of cochlea – look like snail – coiled tube and uncoil it long tube and make cross section and what it looks like - Features - Obvious thing is chambers all three chambers filled with fluid not empty chambers fluid filled chambers - Two membrane strcuutre 1 tectorial another is basilar membrane - Between two membrane is hair cells – auditory receptor cells send sound vibrations and convert signal to ap - Air is sandwich by two mebran and place transformation step takes place Hair cells - Blown up image of one hair cell - Cell body and sterocilla and is embedded in tectorial membrane - Mechanical design allow to generate ap Transduction - Attached to tector membrane bend cilia even if tiny movement or dearrangemnt enough to bend cilia structure whenever bending causes change in mebran potential - Whenever bending change in membrane potential in hair cell - tip link stretching causes opening – cilia bending strecthin motion – and positive ions move in and cuase membrane potential not all or none more cilia more severe more cilia more dramtic change in memebrane potential - membrane potential change vesivle bind to receptor at terminal and trigger ap and travel along auditory pathway - ion channel is trpa1 – mechanosensory ion channel – cilia binding in hair cells caused by air vibration – vibration in liquid in cochlear - those auditory nerve pulses travel along cranial nerve 8 cochlea organization - tonotopically – freq of soundwave structure capture or sense - stimulate hair cells in differ areas - hfreq proximal end - lowfreq at peak piano - hf in proximal and lowfr in apical side or distal side - complex sound tone carries mixture of freq and appl and mixture arrive stimulate cochlea in different areas - consequence if damge in certain area then lsoe ability to hear freq - aging causes lose of hearing in high freq wave by hair cell in prx region - some lose ability lose all ability of soundwave and artificaily generate sensation by implanting device implant - same idea - know arrangement of different part of cochlear introdudce artificla electrixla stimuli in cochlear - capture soundwave and divivde to different sound freq and sound freq to electrical signal - coiled electrode covering entre cochlear - not recreate complexity of ntural sound but mimic it pathaways - soundwaves to ap - auditory pathway - 5 steps - Invervate neurons in cochlea nuclei in hind brain in blue - Aud nerves carry signals and synapse neurons in cochlear nucleus blue and other in red - Next another cluster of nuclei called superior olives - From cochleas nuclies to olives is bilateral exchange - Then to inferior coliclus in midbrain receive from superior olive in medulla - Nuclei in thalamus – mgn to auditory cortex - Not complety red or blue bc mixing of neural signal - Mixing at infer coliculus and olives ? Primary - Located temperal lobe structure - Pac – oranziation of pac is tonotopic or freq dependent map at level of pac - Tonot
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