So, lets summarize what I said and complete this lesson. By showing you an integration of all that you, you, you start, you learned this, this, in this, in this lesson. You have a postsynaptic cell, a very simple one, that is without structure, but it is a cell with conductances to synapses. So there are channels being opened here, due to this excitatory synapse. There are ion channels being opened here, due to this inhibitory synapse. And this synapse is when they start to be activated operate on this cell. For example, when you active this synapse, in this time, the voltage, the membrane voltage will grow positively due to this synapse. When you activate this other synapse, synapse number two, if you active the inhibitory synapse here, you will get a negative voltage coming here. So this will be your EPSP, excitatory postsynaptic potential. This will be your IPSP, inhibitory postsynaptic potential. And these two may interact in time because there is, what we just discussed previously, the time constant. So if the EPSP, the activation of the excitatory synapse, and the activation of the inhibitory synapse, sit one on top of the other, then you will have temporal summation between the excitatory and the inhibitory synapse. If you had many excitatory synapses another one here. Another one there. And they activate that, that, that, that, that, that, that, with some order in time, you will get temporal summation of EPSPs and IPSPs. And if I record in this cell body, in a real cell, in our brain, you will see all the time the synapses being activated. It looks like this. Resting voltage, resting potential minus, minus 70, and suddenly a synapse is active, you see PSP, PSP, IPSP, IPSP, EPSP, EPSP, IPSP, IPSP, like this. [SOUND] . Many, many, many synapses generate a postsynaptic potential. Some of them are excitatory, EPSPs. Some of them are inhibitory, IPSPs. And they interact in time because of this temporal summation. And you will see next, the next lesson, that it very much depends where this voltage perturbation goes to. From resting potential more negatively, or more positively, and how much positive it goes. I will show you next, next lesson, lesson number 4. That if this voltage becomes enough positive, enough depolarizing, crossing a certain threshold you will get a new phenomena from the cell, the spike. So the spike is a generation of sufficient excitatory synapses building up, not too many inhibitory synapses restraining the voltage. If this summation cross a certain voltage here, you will get a new phenomena, the spike, the action potential, but this is for the next lesson.