what do you notice?neuralcrossroads.ucsd.edu/files/2017/02/brainwaves_l7.pdf1) the after...
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Whatdoyounotice?
Classactivity:passingaballbackandforth
Whenconnectedneuronshaverepeatedinteractions:
1.Whathappenswhenaneuron“dropstheball”?
2.Aretherepotentiallynon-optimaltimesforaneuronto“passaball”toanotherneuron?
Theconnectivityofacircuitcanshapeitsrhythmicactivity
Twoexamplesofinhibition-basedrhythms:
InterneuronNetworkGamma(ING)OscillationsPyramidal-InterneuronNetworkGamma(PING)Oscillations
Theseoscillationsarisefrominteractionswithinhibitoryinterneurons,whichprojectlocallyandtransientlysuppressspikingactivity.
InterneuronNetworkGamma:
Theconnectivityofacircuitcanshapeitsrhythmicactivity
other interneuronsgenerateinhibitorypost-synaptic
potentials(IPSPs)
afterhyperpolarizationGray=singleactiveinterneuron
Black=twoconnectedneurons
Interneurons projectlocallyandusuallyinhibitotherneurons
Whittington, InternationalJournalofPsychophysiology,2000
afterhyperpolarization
InterneuronNetworkGamma/Beta:
TheconnectivityofacircuitcanshapeitsrhythmicactivityIPSCAmplitu
de
0.5nA
100ms Whittington, InternationalJournalofPsychophysiology,2000
Howdoesthefrequencychangeundereachoftheseconditions?
Positiveallostericmodulators (PAMs) thatenhancesGABAA receptorfunction.
Negativeallostericmodulator(NAM) thatreducesGABAA receptorfunction.
ING oscillationsarisefrom:1) Theactivationofmanymutuallyconnectedinterneurons
Thefrequencyisdependentupon:1)Theafterhyperpolarization(AHP)periodoftheinterneurons3)Thetimecourseoftheinhibitorypost-synapticpotential(IPSP),specificallythedecaytimeoftheinhibition
Theconnectivityofacircuitcanshapeitsrhythmicactivity
TheconnectivityofacircuitcanshapeitsrhythmicactivityPyramidal-InterneuronNetworkGamma:
Pyramidalneurons projectoutsidearegionandusuallyexciteotherneurons
II
E
Inthisscenario,either:
1) Interneuronspacethepyramidalneurons2) Pyramidalneurons recoverfrom inhibition first,andpace
theinterneurons
TheconnectivityofacircuitcanshapeitsrhythmicactivityPyramidal-InterneuronNetworkGamma:
II
E
Pyramidalcellsandinterneuronsbothparticipateinsynchronousgammaaftertetanicstimulation.
Whittington, InternationalJournalofPsychophysiology,2000100ms
20mV
4mV
1mV
TheconnectivityofacircuitcanshapeitsrhythmicactivityPyramidal-InterneuronNetworkBeta:
II
E
BathapplicationofthiopentalaffectsPINGinamannersimilartoING
Whittington, InternationalJournalofPsychophysiology,2000100ms
20mV
4mV
1mV
TheconnectivityofacircuitcanshapeitsrhythmicactivityPyramidal-InterneuronNetworkBeta:
II
E Pyramidalneuronscanhavealongafterhyperpolarization (AHP), causingthemtoskipgammacycles,whileinterneuronscontinue tofireatgamma
Whittington, InternationalJournalofPsychophysiology,2000
100ms
4mV
TheconnectivityofacircuitcanshapeitsrhythmicactivityPyramidal-InterneuronNetworkGamma:
II
E
Neuronparticipation inrhythms isdynamic(changing)
InitialpyramidalneurongammaactivityslowsduetolargeAHP,andfinallybecomesING
Whittington, InternationalJournalofPsychophysiology,2000
50mV
400ms
InING andPING:
Inhibitoryneuronshavetheabilitytoinfluencethetimingoflocalspikingactivitybycreatingwindowsinwhichactivityissuppressed.
Conditionsthatalterthesewindowswillchangethefrequencyoftherhythm.
Whenconnectedneuronshaverepeatedinteractions:
1.Whathappenswhenaneuron“dropstheball”?
2.Aretherepotentiallynon-optimaltimesforaneuronto“passaball”toanotherneuron?