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Current time:0:00Total duration:7:44

Video transcript

in this video we're going to talk about some Madison station so if we have someone walking down the street he's receiving all kinds of information from the world around him so he's in receiving different types of sensations so different types of sensations he's also receiving information about different intensities of these sensations so is it really hot outside is it kind of hot outside so he's receiving information about the intensity of the different sensations he's also receiving information about the timing so when does he set his foot down on the ground when does he lift the foot off the ground if somebody drives by him and throws a hamburger at him when does the hamburger hit him when does the hamburger stop hitting him so there's also information about timing that he's receiving from the world around him and finally he's also receiving information about where in his body the sense is originating so if a bird you know comes by and pecks his arm the brain needs to realize that oh there's something going on on my arm so there's also location so information about location needs to be addressed so what are the different types of senses that he can have as he's walking down the street so of course we need to get information about the temperature so is it really cold outside is it really hot outside so the sensation of temperature is something known as thermo ception thermo ception he also needs to get information about pressure so when does he set his foot down on the ground what if somebody came by and like we said through hamburger Adam how hard did the hamburger hit him so we need to get information about pressure and this is also known as Meccano ception so Meccano ception so what else does he need to know he also needs to get information about paint so if the bird did come down and peck his arm it would be a little painful so he needs to get information about pain and pain is known as no c-section and finally he needs to get information about where his body is in space so as he's walking along is he really close to the sidewalk is he close to someone else he needs to get information about his body's location in space and this is known as proprioception so these are the different types of information that he needs to acquire from the world around him through his body surface so he also needs to know some something about the intensity of the various stimulus stimuli so if it's really really hot outside it'd be really nice to know that versus if it's kind of cold outside so the way intensity is encoded in the body is by how quickly the neurons fire so there are different neurons that are sensitive to temperature their different neuron sensitive pressure so if it's really cold outside then the neurons might not fire that much so they might fire a few times so if it's kind of cold outside it's not that hot build Aspire a few times over the course of a minute but if it's really hot outside they might fire a whole bunch of times and so how quickly they fire is how intensity is coded so another thing that we need to acquire from our environment is the timing so if a bird were to come down so we've got a little bird coming down he's going to Peck this man he's coming down and he's flying he's got a stray shot for the arm and he pecks him right there so the guy actually needs to know okay when does the pecking start when does the pecking stop and so in order for a neuron to encode timing there are three different ways they can do that so there's a neuron that the entire time the bird is pecking him it will consistently fire action potentials so this type of neuron is non adapting and it's non adapting because you can look at the action potentials and there's an equal amount of space between each successive action potential so basically the entire time some sort of stimulus is being applied there's no change in the firing rate another type of neuron will start firing really really quickly so there's a whole bunch of action potentials and then over time it will slow down the space between the action potentials increases and so as you can see here it starts firing really fast at this at the beginning of the stimulus and then it slows down so the spacing actually increases and this is known as a slow adapting neuron and it's slow adapting because it's really slow to adapt to the change in the stimulus another type of neuron is going to fire really quickly as soon as the stimulus starts and then it's going to stop firing and then it will fire again when the stimulus stops so this is known as a fast adapting neuron so the fast adapting okay and then what's the final piece of information that we need to get from the world around us so if this birds come in into Peckham he needs to know that it's pecking his arm and there needs to be some sort of way that the brain is able to register that okay it's my arm that's being pecked not my leg and so in order for the brain to do that it relies on things called dermatome so if we were to draw a person here there is the torso he's got his arm he's got his other arm and he's got his legs so each part of the body child a part of the body is innervated by a particular nerve and that nerve goes up to the brain so if a birds pecking its arm we know okay this arm is being pecked and so that this arm will send a nerve to the brain and the brain is able to figure out okay it's this arm that's being pecked all right so I clean that up a bit so let's imagine that we've got somebody flying in from the sky and he's headed right at our innocent bystander walking down the street and this man just happens to have a red cape and people call him a superhero but he's headed right for this guy so as this guy's coming in he's going to crash into this poor fella walking down the street so what types of receptors would be activated in this case so temperature no not really there's no change in temperature pressure definitely this guy's just bombarding right into this innocent bystander so he's going to feel a lot of pressure from the superheros body pain you betcha he's going to be in a lot of pain this guy's come in a 100 miles-per-hour headed straight for this guy he's probably going to feel a little pain and he's probably also going to get knocked off his feet so he's going to feel a change in position so these three different senses will go off let's look at intensity how intense is this raction it looks pretty intense you've got a superhero coming in right at you so his neurons all these three different types of neurons are going to fire really really quickly let's look at timing so we're going to definitely have some non adapting neurons firing because the entire time that this guide the superhero is in contact with the innocent bystander there's going to be different neurons firing steadily just so that it lets his brain know hey there's something going on here they're also going to be fast adapting neurons that will fire as soon as the superhero hits the innocent bystander and then as soon as he gets off of him so there's going to be fast adapting neurons firing and there will also be slow adapting neurons firing the entire time that the superhero and the innocent bystander is making contact so what about location so the superheroes headed straight for this guy's torso so the entire torso is going to be lit up maybe some of his arms are going to be lit up so basically they're going to be nerves that innervate these three different parts of the body and they're all going to be sending information to the brain saying hey we've got you know a little bit of pain some pressure and there's a change in position here