What determines the amplitude of an IPSP or EPSP?Slide 2What is the reversal potential (Erev) for a channel?Synaptic IntegrationSummationSlide 6The conduction of EPSPs down dendritesSlide 8Slide 9Slide 10Slide 11Slide 12Slide 13SummaryWhat determines the amplitude of an IPSP or EPSP?How could you tell the difference between a chemical and electrical synapse?Which of the following equations will tell us the amount of current carried by an ion through a channel?A. (Eion)gionB. (Vm-Eion)IionC. (Vm)gionD. (Vm-Eion)gionE. (Vm-Iion)gionWhat is the reversal potential (Erev) for a channel?A. The potential that equals the equilibrium potential for an ion that a channel is permeable to.B. The potential at which there is no net current through a channel.C. The potential at which all of the ions the channel is permeable to are carrying an equal amount of current.Synaptic Integration•What happens when a mix of inhibitory and excitatory inputs are active simultaneously? •What is shunting? Why is shunting considered inhibitory?• How are metabotropic signals integrated with ionotropic signals?Summation•Temporal•SpatialThe conduction of EPSPs down dendrites•Decay as they travel•The amount of decay depends on the distance of the synapse from the soma as well as:–Dendritic membrane resistance–Dendritic diameterRemember: Dendrite diameter is not constant!The GABAA receptor is permeable to Cl-. If ECl is -65 mV and the resting membrane potential is -65 mV what will happen if you are recording from a neuron with only GABAA receptor containing synapses active?A. There will be an outward currentB. There will be an inward currentC. There will be no visible currentIf a GABAA receptor containing synapse is activated, and an EPSP has momentarily increased the local membrane potential to -60 mV near the synapse what will happen to the EPSP?A. It will increase in amplitudeB. It will decrease in amplitudeC. It will remain the same amplitudeInhibitory synapses can act by shuntingIf GABAergic synaptic activity is “invisible”, how do we measure it experimentally?A. Only measure them in the presence of EPSPsB. Change the Cl- concentration on either side of the membraneC. Inhibit the Na+/K+ pump to raise the resting membrane potentialModulation by metabotropic receptorsSummary•PSPs sum when they are in the same place at the same time–Temporal summation is when the PSPs originate from the same synapse–Spatial summation is when the PSPs originate from different synapses•Shunting inhibits EPSP conduction by making the membrane leaky (usually to Cl- ions, which want to keep the membrane potential near the resting membrane potential)•Metabotropic receptors mediate their effects slowly but last much longer–Sometimes open ion channels indirectly–Sometimes only signals