Відео

I've heard of it, but I've never used it, and I don't know anyone who does. But from scanning through their code base, it is being actively maintained, so that is always a good sign. Looks like it would be something useful to be familiar with, because of t's general purpose nature.

Good question. It is fundamentally just a convention. When voltage clamp papers were first being published, some people would show positive current entering the cell via ion channels (and hence being opposed by negative current being applied by the amplifier) as going up the page (i.e. positive). Other people would show it as a negative current (because that is what the amplifier actually did). The convention became to report what the amplifier did. This is because this is actually the truth. As in, if we show the current that the amplifier applied, we are truly, definitely showing what the amplifier applied. We ASSUME (or perhaps hope) that this is equal and opposite to the current flowing through ion channels, but it is never exactly accurate (and in some cases can be very far from accurate). So we stick to what we know happened, and hope it is an accurate representation of what happened at the ion channels.

I understand the confusion. It is a very common source of difficulty. I think the confusion primarily comes what "current" means when it comes to a capacitor. But the basic answer as to "why" is because "physics". In circuit theory, it's called "Kirchhoff's Current Law", which states that the sum of all currents entering and exiting a node must equal zero, i.e. if a positive charge enters a place, then either a negative charge must enter, or a positive charge must leave. But to try to give you a mental model, imagine a tiny bubble of membrane, with a single sodium channel in the membrane. Inside our bubble there are an equal number of positive and negative charges, and the same applies outside the cell, so the transmembrane voltage is zero. The sodium channel briefly opens, and despite there being no electrochemical gradient, a Na+ ion happens to move from outside the cell, to inside the cell. The instant that happens, the electric field inside the cell changes, with the voltage inside the cell now being positive. This attracts some negative charges outside the cell to the membrane, and repels some positive charges. This net movement of charge IS a current. Indeed, it will (in total) exactly equal and opposite to the current that moved into the cell. This current is usually described as the capacitive current. While the movement of the ion through the ion channel is called the ionic current. So Iion = -Icap. i.e all the movement of charge into a via ion channels cell, ends up charging up the membrane capacitor. This rule only applies in "isopotential spheres" like out membrane bubble. But in large cells, it fundamentally still holds, it's just that there is one more place for current to flow: down dendrites and axons, i.e. axial current. There you can say: Iion = -Icap -Iaxial. I hope that helps.

Yeah, sorry about that. I had a newborn at the time.

Loving these videos Bill

Sorry about the yawns. I do feel bad about them. But I had a new born at the time. I'm going to re-record them in the second half of this year hopefully.

I have a New Zealand accent, because I grew up in New Zealand. But if you're having trouble, turn on closed captions.

what do you mean by 'improve the speech'. the man took out time to explain you. now you want him to 'speak different'?!?!??!!?!??! audacity.

Can it? Absolutely. It wasn't invented for doing that, but it's pretty common these days.

So, theoretically, you can build up an entire neuron in circuit builder, compartment by compartment. But I would strongly advise against it. Typically, one would build the neuron with Neuron Code (i.e. in a HOC file), then just import the model into circuit builder, which then just appears as a single element in the circuit. Then you can add on whatever circuit you want.

@@bilz0r Thanks, I need to do it due to variations of the components. BTW, would you mind if I ask you how I can import the model into Linear Circuit?

@@mohammadrezakhodashenaskha5006 Variation of what components? Like membrane resistance? You don't need the circuit builder for that. You get access to the soma of the cell with the second from bottom component in the Linear Circuit Builder, Arrange menu. Right now I can't remember what you do if you want access to any other component.

@@billsneuroscience2598 Thanks but I'm afraid I couldn't understand how I can get access to the cell's soma from the the second from bottom component in the Linear Circuit Builder! You mean the "Keep Connected" toggle?

@@mohammadrezakhodashenaskha5006 No, on the other side of the window. Below the resistor, capacitor... op amp. Second from the bottom.

Hi Victor, the threshold where the input rate must be above to cause LTP (or be below to cause LTD) is usually called θM or "Theta M"

@@bilz0r Thank you!

@@bilz0r Thank you!