Review Session NSCI 3310
Popular in Cellular Neuroscience
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This 3 page Class Notes was uploaded by Emma Notetaker on Monday October 12, 2015. The Class Notes belongs to NSCI 3310 at Tulane University taught by Jeffrey Tasker in Summer 2015. Since its upload, it has received 88 views. For similar materials see Cellular Neuroscience in Nutrition and Food Sciences at Tulane University.
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Date Created: 10/12/15
Review Session inhibitory intemeuron 90 GABA neurotransmitter I GABA CNS and spinal cord I glycine only spinal cord receptors I GABA 9 GABAA receptors ionotropic 0 Cl channel D fast signaling through ionotropic B when GABA released binds to receptors and opens Cl channel D Cl ows in weak driving force OUTWARD membrane current coming in I GABA 9 GABAB metabotropic I glycine 9 glycine receptors IPSP reversal more and more positive 9 bigger and bigger inhibitory outward current at rest I Vreversal 70 mV I equal to Cl equilibrium potential because SINGLE current channel I going negative to reversal reverse direction to INWARD Cl leaves cell I reverse IPSP depolarizing V NOT EPSP no threshold Cl current GABAA receptors heteropentamer 0t 3 5 y p subunits Cl channel modulatory sites 1 GABA ligand 2 barbiturate agonist 3 benzodiazepine agonist 4 steroid agonist 5 picrotoxin antagonist 6 ethanol agonist agonists for GABA INCREASE INHIBITION depressants antagonists decrease inhibition outward current composed of outward single channel currents Part 2 MEPP generated by Miniature endplate currents aka unitary response all synaptic release is quantal in nature quantum VOLUME OF neurotransmitter in synaptic vesicle quantum volume can change from one neuron to the next usually pretty stable for given synapse one quantum causes unitary response everything else is multiple of unitary response nicotinic uxes Na and K in opposite directions muscle ber more hyperpolarized than neuron sodium dominates current 9 inward membrane current causes depolarization at NMJ ONE big EPP can drive muscle ber 9 contraction single synapse in CNS cannot generate EPSP big enough to reach threshold require integration of multiple synapses to generate AP reversal potential all glutamate synaptic currents have reversal potential of OmV positive to 0 mV K ef ux is greater than Na in ux 9 reversed current outward leads to hyperpolarization when no voltagegated in uence currentvoltage graph will be linear for AMPA and Kainate nicotinic as well in NMJ GABA synaptic current has reversal potential of 70 mV in graphs potential will be opposite direction of current AMPA and Kainate Na and K ion uxes mixed channel current similar to nicotinic receptors in terms of currentvoltage relationship reversal OmV only ligand sensitive to glutamate NMDA magnesium block NOT linear currentvoltage relationship looks the same as AMPA or Kainate graph in positive sector as you become negative almost entirely blocked at resting potential as you depolarize membrane Mg kicked out if glutamate is present will activate inward current around 30mV Mg is almost all kicked out I NOW NMDA current will act the same as AMPA kainite nicotinic current graphwise glycine AND serine are coagonists need one or the other even if glutamate WILL NOT open channel without them does not contribute to peak current of overall synaptic current SLOWER than AMPA kicks in later mixed NMDA and AMPA synapses common baseline activation of synapses mainly AMPA if activate enough in high enough frequency membrane will become depolarized enough to kick Mg out NMDA will be activated once Mg out Ca in ux due to NMDA receptors 9 LTP I plasticity I new dendritic spine formation I potentiated synaptic transmission I Ca VERY powerful NMDA doesn t contribute to peak because slower than AMPA IONOTROPIC channels FASTER than METABOTROPIC passive properties NOT AP generation passive ow 1 capacitance ability to store charge gives us Vm 2 resistance of open channels 3 axial resistance resistance of cytoplasmic uid membrane can store charge like a battery 0 add charge 9 some charges membrane causes capacitative no movement of ions with membrane 0 as soon as membrane starts to charge some starts to leak out through leak channels ionic current degree of depolarization dictated by Ohm s law V IR IV relationships is linear until threshold because then voltage gated channels are activated time constant determines kinetics of integration at given point in space anywhere in the membrane INDEPENDENT of distance T RC 0 decaying by 63 over each time constant exponential decay