BIPN 144 Week 10 Notes (part 1)

BIPN 144 Week 10 Notes (part 1) - BIPN144Week10Notes(Part1)

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Unformatted text preview: BIPN144Week10Notes(Part1) Note:ThishasnotbeenreviewedbyDr.Bierandmayhaveerrors.Always trusttheprofessoroverthesenotes. Today'slecturefocusedprimarilyontheseaslugaplysiaasamodelforlearning. Dr.Bierstartedbyexplainingthatifyoutouchthesiphonofanaplysia,itwillreact bysortofsuckinginandprotectingallitsorgans.Howeverifyougentlytouchits siphonoverandoveritwillbecomehabituatedandstopresponding.Persistently abusingtheseaslugleadstolongtermsensitization. Hethendelineatedtwoexperiencebasedmodifications:Habituation(whichwe don'tcaretoomuchabout)andSensitization. Habituationhastwosubparts Veryshorttermhabituationcanbecausedbyneurotransmitter depletion Shorttolongtermhabituationcausedbychangesinneurotransmitter release Sensitizationhasfoursubparts Veryshort(notveryimportantforthisclass)canbecausedbyan increaseinCa++inthesynapse,whichincreasestheefficiencyof neurotransmitterrelease. Shorttermsensitization(minutes)inthiscasea5HTfacilitating interneuronsprays5HTonthepresynapticneuronactivates adenylatecyclaseincreaseincAMPwhichcausesthedisassociation andactivationoftheproteinkinasecatalyticsubunitswhich phosphorylatessomeK+channels.BlockingtheseK+channelsand therebypreventingK+fromleaving,increasingthedurationof depolarizationandthereforetheamountofNeurotransmitterreleased. AssociativeFacilitation(minutestohours)thisrequirespairedstimuli sothatthesynapsebeingpotentiatedmusthavejustfired(loadingthe synapsewithcalcium)beforesecondstimulus. Mechanism:Precondition:activationofpresynapticcell(i.e.mantel sensoryneuron)justpriortotailstimulustransientincreased[Ca++] Ca++bindstoCalmodulinCalmodulinCa++bindstoadenylate cyclaseandpotentiatesenzymaticactivityincreasedcAMP production. Fromhereitisprettymuchthesameastheshorttermsystem,onlyona muchlargerscale. Longtermfacilitation(hourstodays)prolongedpresenceofhighlevels ofcampprolongedpresenceofactivatedkinasetravelsbackupto thenucleusandphosphorylatesatranscriptionfactorcalledCREBthe nowactiveCREBbindsandactivatestheexpressionofaproteasewhich directlycleavesapartthetwosubunitsofthecAMPdependentprotein kinase(nocAMPnecessary)increasedlevelsofactivecatalyticsubunit moreblockedK+chanelsetc. Also,PhosphorylationofCREBleadstoarborization(branching/growth) ofthepresynapticneuron(makesitbigger). Then,brieflyattheendofclasshementionedthehypocampus,aportionofthe brainnecessaryforstoringnewmemories.AndmentionedLongtermpotentiation. Therewillbemoreonthisnextlecture,butherearethethreecriteriadefiningLTP: 1) cooperative(morethanoneinputrequired) 2) Associative(requiressimultaneousfiringofinputs) 3) Specific(onlytheactivepathwaysarepotentiated). ...
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This note was uploaded on 11/10/2010 for the course BIPN BIPN 144 taught by Professor Bier during the Spring '10 term at UCSD.

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