So in those conditions, actually, that don't have much assistance to help them to navigate to [FOREIGN] input. So actually to rely heavily on the touch sensation. [FOREIGN] A mouse, rat, to navigate without visual input. [FOREIGN] Okay. Whisker, right? Actually it's a whisker provide actually very important information for this kind of explore this space. For example, maybe, there is a wall, or something actually in the front. The risk thinking make it a gentle touch, and then the animal will know actually there's something there. [INAUDIBLE] That thing, right? Okay, so today we will talk about actually the somatosensation. As we discuss, somatosensation actually include a lot of sense, okay? Including temperature, pain, touch, of course and some other chemical sensation for example the proton to the exit, to the detection. And this happens actually on the skin. The skin, of course, actually is the largest sensory organ in our body. Also maybe internal organ. For example, the heart, the beating. And also maybe some other, also happen in the brain. Some kind of temperature sensing. So for this actually, the start is actually not so advanced, okay? But actually, the main two sensations, for example the touch and pain, then I represent more at the rate status. So today we're focusing on the touch and the pain. As we mentioned, on the touch, we use quite often daily the daily life. For example, these kinds of surfaces. It's very easy for you to tell which is the glass surface, which is the stone wall right? Or this kind of surface just a gentle touch then you can differentiate these three. Also the touch sometimes actually quite powerful, right. So for the animal, for example, for the cat, you just touch the head and it then will enjoy actually your touch, this animal. And of course, this kind of thing Is related to the affection or the emotion of this animal. It's a very gentle touch representing maybe the care to this animal. Right. So your care would be appreciated by the receiver. So underlying this mechanism of course. There bi-directional signaling. Why especially from your hand? Your touch the animal, the hair and the, sensation from our, and also from the animal and he will enjoy your touch, also through the touch sensation. Through this, the hair, the skin underlies the hair. So, let's take a look. What kind of neurostructure is responsible for this kind of sensation. This is a cartoon to show all kinds of somatosensory system, okay? Let's take a look at this one. Of course, this is a hairy skin. Your skin has this hair. And here we have, once something like this, this is the hair, and then there this called a hair follicle, and then there is some kind of full neuroaxial terminal, here surrounded this hair. And then, this actually will go to the neuron cell body located quite far away in this. Those are root ganglia, [FOREIGN]. And then this neuron actually is send one process out. This is the process. And then we go two directions. Why is go to the peripheral. In the weight of the hair, yeah? And at the other end of the axiom, where it goes to a CNS, for example, the spinal cord. For this one, let's take a look. The purple one, this one. We call a beta fiber. This fiber has the properties, it's heavily myelated. So the outside actually surrounded by a. [FOREIGN] And let's take a look at another one. This one, this one is a little bit different. Also called a beta fiber but I should say the notation pattern are different. Actually, this one through the width in the hair follicle. This one then we knows it's two different structure these structure is called micro cell. This micro cell actually require special it's just a some flat cells. Here and this flex cell is for the neuron. Very special and this micro cell actually later people found actually between this micro cell and this axon fiber there may be some significant structure. Okay? Very special. And we, maybe we talk about it later. So for this one is quite obvious, right? So maybe you have a mechanical force. Remove the hair, and then the sensory input is from this guy, from this exoterminal. That means in this exoterminal there is some kind of mechanical state of channel, so you have the whole move. Maybe a course, the change of this member and structure. And then the channel. Then we are open. And the end sewed in and calcium may be where going to the cell, the cell And then the fire action potential. And they send it to the CNS. What happens for this region, [FOREIGN] is the micro cell. They're quite special. People at the beginning think I should only the axial terminal, the neuron fiber. Actually sends the mechanical force but later people found actually maybe this is a micro cell. Also can sense a mechanical force and when they sense the mechanical force then they will release neurotransmitter and then to excite these fibers. Okay, this another way of this signaling. And this, a beta fiber, actually carry the touch inflammation to the CN, to the spinal cord. For the spinal cord. Then they are the why to the to, this is called both part. This is the side. And then this is the gray matter inside here. Like a butterfly. And we called this one, this is a [FOREIGN]. Of course there are two, a pair. One here and the other one here. And for this, of course, there is a range of. This is a.
