NPB 100 Lecture 6

NPB 100 Lecture 6 - Lecture 6 -how synaptic current lead to...

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Lecture 6 -how synaptic current lead to PSP -RC Model -how PSP arise -factors determining their size and duration -summation of postsynaptic potential -how potential spread within a neuron -excitation and inhibition -introduction to electrical synapses -membrane capacitance -measure of the ability of the cell membrane to align charges across it -membrane is thin enough for ions across the membrane to interact -charges are aligned across the membrane due to membrane potential -if we have a receptor that is a ligand-gated channel selective for particular kinds of ion, then it will gate the flow of a current that is proportional to the reverse potential for whichever ion that flows through that -normally closed, but if you bind the transmitter, you open the channel. If you think of it as a variable transistor, you close that switch and then the channel can flow. When this happens, slide 1 is showing the same thing he drew on the board. -resistance is the reciprocal of synaptic conductance -when the cell is at rest, and we activate this pathway and there is a difference between the equilibrium potential and membrane potential, then a current will flow
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-depending on the difference between the potentials, the conductance changes, will get a current that flows in the cell. This is the synaptic current -how big is that synaptic current going be? (slide 2) -depends on how big the change in conductance is -how many ligand-receptor channels available -how big is the driving force operating on the ions that can move through that channel (depends on difference Eq and Em) -slide 3: voltage clamp a cell and measure the synaptic current that flows as they held the membrane at different potential -From -200mV to -40mV, the current gets smaller and almost disappear at 0, and then the current reverses current -when the difference b/w Em and Eq are the same, the current is zero even though you activate the conductance -reversal current indicates that the ligand-gated channels operating in that synapse is non-rectifying -slide 4 -what is determining the postsynaptic potentials -change in postsynaptic potential is proportional to the change in postsynaptic current times the input resistance -input resistance is the same thing as membrane resistance
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NPB 100 Lecture 6 - Lecture 6 -how synaptic current lead to...

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