What is the Thalamus? - Sensory Processing, Consciousness, Attention

[Music] all right guys welcome to psych explain in this video we're going to break down the thalamus specifically what role does a play in re-link sensory information to the cortex to be interpreted and processed so let's dive in now the first thing i want to draw your attention to is we look at this big structure of the brain is how noticeable the thalamus is by the way you can use word thalmai because we have two of them one in each hemisphere there's a lot of structures of the brain that are really hard to identify because there are no defined borders right just a bunch of neurons clustered together but the thalamus it's really hard to miss right these two huge masses of gray matter that sit right in the center of the brain now you could also look at thalamus from a different angle right this person would be facing towards me this would be our left hemisphere and with this angle we know that the thalamus is sitting right on top of the brainstem i've often heard of thalamus is called the gateway to the mind because the information flows through the brainstem or away from the cortex it has to flow through the thalamus or at least majority of the information right it's kind of that bridge between the cortex and the rest of the body we'll come back to this visual and this visual as we talk about its functions now there's our next question what does the thalamus do now this is up for discussion and debate now even though the structure looks very simple and easy right these two circles it's made up of a lot of sub-regions of nuclei right and researchers are still trying to investigate what each structure does but for our purposes we're going to focus on four primary functions right things that we know it does but i'm guessing in 5 10 15 years from now i'm sure many of these will get longer and longer and longer so let's dive in now the first function of the thalamus is what we're going to label as the relay station right this is actually what we're going to really focus on today the majority of information that flows through the brainstem right throws through the brain will flow through the thalamus and then project onto the cortex right it's kind of that relay station that goes to and from the brain another way to think about the thalamus is that it's involved in attention right so we talked about our introduction right this is kind of the filter i want you to think about how much sensory information like we receive on a daily basis right vision sound audio and all that kind of stuff you're bombarded with information and it's information overload right your brain can't pay attention to all that information that must by prioritize what it should focus on and we know along with the prefrontal cortex the thalamus plays a big role in deciding what we should focus on right just imagine you're a big crowd of room having a one-on-one conversation with somebody and there's a lot of background noise you're able to focus on this conversation and filter out everything else your thalamus plays a role in that all right so we have realization we have tension what are some other roles we also know thalamus plays a role in actually change there we go let's use a different color consciousness okay consciousness okay what do we know about consciousness when you have consciousness is being awake and alert right if you damage your thalamus that can actually make you go into a coma okay a vegetative state we've also seen case studies where if you stimulate this region right electrically stimulate this region you could actually have some more wakefulness right somebody could wake up or or become more aware of their world after being in a coma or a different vegetative state okay so that's how we know consciousness plays a big role and then lastly we know it plays a role in sleep okay now there's a lot of parts of the brain that evolved in sleep and one of them is the reticular formation or the reticular activating system and that flows through the brain step and all this information is going to flow up ascend through the thalamus up to the cortex and this is going to make you aware it's going to make you wake up in the morning it's going to make you alert and that's how we know this plays a vital role so there's our big four relay station attention consciousness and sleep now what we're going to focus on in this video is specifically number one which is our relay station and we mean by this is our sensory pathways let's go over our sensory pathways we have our auditory pathway we have our somatosensory pathway right tactile information we have our visual pathway and our gustatory pathway right how does information ascend flow through the nervous system right and how does it received by the thalamus and project onto the cortex now notice there's one sense missing do you notice which one's missing are sent to smell our olfactory system why is that we'll focus on why that is missing at the end of this video okay all right let's start with the first one let's start with hearing so how does information enter our ear and how does it receive by thalamus and then where does it go from there well the first thing i want to understand is you're actually not hearing my words i know that might sound confusing what you're hearing are sound waves right your ears are picking up sound waves and these sound waves are being picked up by your pinna they're being funneled through through your auditory canal right through your tympanum membrane and eventually they'll reach a part like the snail-like structure called the cochlea and this is where sound waves convert into action potentials or electrical impulses and this information is going to travel through the auditory nerve right here through the brainstem and once it gets the brainstem what's going to happen we've talked about this in other videos that a lot of formation is going to travel to the opposing or opposite side of the hemisphere right so everything happens in this hand will be processed by this hemisphere everything in this hand will be processed by this hemisphere everything's crisscross right so this information is going to travel over here which is going to synapse with a another neuron okay on this side and this information is going to flow through the brain right this is the cerebellum on the back side through the thalamus okay through the thalamus specifically a part called the medial geniculate nucleus you might heard terms like medial or lateral or anterior posterior in science or psychology and what that's referring to is the location right medial means towards the middle and lateral means away from the middle okay all right so where does this information go how it's going to process out well this is going to stand us with another neuron and this is going to flow through our auditory cortex okay our auditory cortex there we go our ac okay and this is what's going to process what we hear right this is going to let you know that you're speaking words or that you're hearing uh music right you're hearing somebody's language right this is our auditory cortex we'll kind of shade the since we know what we are looking at there's your auditory cortex okay all right so there's our auditory pathway the next one our most dominant sense is our visual pathway okay which is right here and instead of sound waves what what energy are we taking in what we're taking in are light waves whether it is you know shorter light waves like the color blue or longer waves like the color red okay and that's going through your pupil on your iris and your lens and eventually it's going to reach a part of your eye called the retina right this is where information is converted to action potentials just like our auditory nerve this is our optic nerve now instead of using this angle we're just going to focus on this diagram because the eye doesn't go through the brain stem right because the eye would be up here so how would this work well just like we just said information uh you know flows through the eye through the retina which is in the back of the eye that information is going to flow through the optic nerve to the thalamus like the majority of our sentence now the auditory system is the medial geniculate nucleus what is fission this would be if i kind of do a little back here the lateral geniculate nucleus so we have the mgn and the lgn a nice way to think about it is m for music right hearing and l for light and for music alpha light there we go and where is this going to go well we have to process what we see so this is going to send us with another neuron and go to our visual cortex which is in the back of the head okay and this is located where let's think about our lobes this would be our occipital lobe right we have different lobes right we're our frontal our parietal temporal and our occipital lobe okay so there would be vision so we have our auditory pathway we have our visual pathway what's next let's talk about our somatosensory pathway our sense of touch now there's two things i want you to think about there are two different sensory receptors there are some that sit right underneath the skin picking up things like you know pressure and vibrations and hot and cold and you know pain that type of thing right so these would be you know on the surface you also have sensory receptors attached to your muscles so let's say this is the muscle in your arm and these are called receptors okay these called proprioceptors so imagine right these are your muscles ligaments and joints so imagine you're moving your arm right you're doing you're working out right doing hardcore are you doing this well that information has also got to be received by your brain or you can imagine i don't know that you know a fly lands on your armor so you can think about a fly or you move your muscles it's all the same and this information is going to flow through the autonomic nervous system to our central nervous system autonomic to our central and just like hearing it's going to cross over in synapse with another neuron okay another neuron and that's going to flow as well up up our brain to our there we go right to our thalamus okay now where does it go from there well the question is where is our somatory system where's our somatosensory cortex right in our parietal lobe that's going to synapse with another neuron and that's going to synapse with r where somatosensory cortex right how cool is that and that is a huge area right this is going to have things like you know our our skin our toe our knee our lips right all the things that make us sensitive is going to be in our cortex so if i kind of shade it all this represents our sensory cortex okay and your arm would of course be somewhere around there okay so there's our auditory system our visual system our cis visual pathway our somatosensory pathway what's left our gustatory pathway right this is our scent of taste now take a look at these little bumps a lot of people think those bumps are your taste buds but they're not these are your papillae or your papillae okay and we look at this angle you know looking at from this side is that your taste buds are located in between your papillae in between these grooves okay and saliva helps break down food so all those taste buds could be activated and these taste buds are connected to taste receptors okay taste receptors you know you got to taste the food you have to have flavor well that information has got to go through not just the brains at first but the cranial nerve different facial nerves right because it's in the middle and that information is going to flow through the brain stub right it's going to synapse with another neuron through the thalamus right here and then it's going to synapse with another neuron now the question is where is taste processed let's take a look in our gustatory cortex which is right here okay now where is this located well we see this little line right here right this is what divides the frontal lobe and the parietal lobe and temporal lobe this is called the lateral sulcus and if you kind of rip it open okay you rip it open you're gonna see this large kind of deep indentation in the brain this is where our gustatory is located right this is what processes things like taste and flavor right your tongue doesn't know you're eating a hamburger it's not until it goes to this area that you can perceive it as a hamburger okay so there's our four systems our four pathways so here's a question what's missing what's missing is our olfactory system our olfactory pathway now why is that missing it is the only one of our five senses that bypasses the thalamus why is that well there's some evolutionary theories of why that is one of them is that it's our oldest most dominant sense and such that millions of years ago we didn't really have a lot of these structures right it wasn't really developed yet another reason it might be more advantageous for smell to go straight to our limbic system right smell and memory and and emotion right we can make quicker decisions so that would be an evolutionary reason why olfactory system bypasses the thalamus really interesting stuff here are our different systems all right guys thanks for watching as i said before the thalamus is a really complex structure and i wonder in 5 10 15 20 years from now what else will learn and what other functions i'll need to add don't forget to like the video subscribe comment below and i'll see you next time thanks for watching

Channel: Psych Explained

Views: 45,625

Keywords: thalamus, sensory cortex, motor cortex, relay station, attention, arousal, sleep, lgn, auditory cortex, temporal lobe, parietal lobe

Id: JBgt5mDRY_g

Length: 12min 50sec (770 seconds)

Published: Wed Mar 17 2021