Hello students. This this lecture is going to be about functional groups of neurons. So we're going to look look a little bit on how groups of neurons work together. So in the in the central nervous system, we have integration. And integration is is all about the connections of neurons between each other. And so you can have groups of neurons that are connected for a specific reason. And so you have these pools of neurons so to speak and these are inter neurons. So they're connected to each other and they're connected in a specific way to create carry out specific processes and so they're defined by these connections. So when we look at these connections um they kind of show how how they carry out this signaling. So they might be for like a planned movement or a memory or some sort of process that is going to be carried out. So it's an um a a a set of signals or a set pathway of signals to carry out a process. And so you're going to have input neurons which start the signal and then how that is carried out whether it diverges and goes into lots of different other neurons or converges and comes together to one site and kind of amplifies that signal. That's kind of what we're talking about. So diverging circuits are pools of neurons that you start in one location. You have a single input and then you can signal multiple sites by like kind of like a phone tree. One one input you signal two and those two signal two and those two signal two and now you've signaled a bunch. So we keep passing it on and and we get more and more signals spreading out. So this is a diverging circuit. And so this is an example of a diverging circuit where you have one input and we're going out to let's say you have one upper motor neuron and you have this is signaling some different inter neurons and then we those are signaling multiple inter uh lower motor neurons and now we've got different motor units that are being recruited for this particular process whatever that is. And this is another one where we have sensory a a sensory diverging um circuit where we have sensation coming in and we will connect to multiple inter neurons and those will also connect to other multiple inter neurons. So we're passing on that information. We're amplifying that signal to other areas. And then convergence circuits do the opposite. So we can have multiple inputs all signaling to one particular area. So we're kind of converging into one one location. So for example, we can have um like if we we can have more than one neuron coming in or sensory information coming into one location in the brain. And so here's an example of sensory receptors we have coming in and they're um signaling specific sensory neurons and they're two are signaling are synapsing onto one sensory neuron. That information is integrated and then that information is passed on to a single sensory neuron but another pathway is also converging and now we get one neuron passing on that information. So this is what we call a converging circuit. And again this I know this is more anatomy but I just wanted you to kind of be thinking about okay how are how is this integration happening and what what are the ways that we can process this information? And so what stabilizes these circuits? What prevents these from from you know going haywire? Well you can have positive feedback. You can have negative feedback. Positive feedback amplifies the process and not really stable, but definitely makes it go faster. But your inhibitory feedback is really what keeps it stable in that if you start this circuit or you start this signal or process going, usually the outcome is going to shut that circuit off in some way. And so we're going to come back and say, "Okay, now we can turn that off. We've got the result we wanted." And so that's going to help control the rest of the circuit. And so um something sometimes we will also see if we're over stimulating a circuit or over stimulating neurons, they will go through something called synaptic fatigue where they they're not going to keep sending the signal and so they get weaker and weaker transmission. That can happen as well. And we also, we'll talk about this later, it's not on here, but things that can happen can be like if you're constantly stimulating something, we can have upregulation and downregulation of re receptors depending on if something is not there, not present or is present all the time. We might want to downregulate it or it's not present. So, we want to be able to pick it up well. So, we'll upregulate receptors so we can change things a little bit within the circuit. So that is our last slide in this chapter, chapter 11. Next chapter is going to be 12. We're going to focus on the central nervous system. I will see you there.