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Beattyetal.,J.Neurophysiol., 2015
Wehavediscussedmultiplephysiologicalpropertiesthatcaninfluence
neuralresonance.Howeasydoyouthinkitisforaneurontochangeits
resonantfrequency?
Isthissomethingthatcouldhappennaturally?
Atwhattimescale?
Magnitude ofImpedance
Modelsofneuronsaselectricalcircuitstounderstandresonance
(due topassiveproperties)
(due toactivecurrents)
Inputimpedance =determineshowmuchaneuron depolarizes inresponse toanalternatingcurrent
AdaptedfromHutcheon andYarom,TrendsinNeuroscience,2000
Toclarify(notonexam):
1.Asthemembrane“charges”
tothenewvoltage,the
charging currentapproaches
zero.
Whenanion channelopensorcurrentis
injectedintothecell,voltagechanges
occurslowlyacrossthemembrane.This
changeisevenslowerinlargecellsor
cellswithmanypassivechannelswhich
“leak”current.
2.Currentflowacrosspassive
channelsincreases
V
Voltageacrossthemembrane
I
Currentpulse
Modelsofneuronsaselectricalcircuitstounderstandresonance
Neuronsthatexhibitresonance have:
PassiveChannel
1) Channelsthatallowthepassiveflowof
ionsacrossthemembraneandenablethe
suppression ofresponses toinputs that
occurathigh frequencies.
2) Voltage-gatedion channelsthatoppose
changestothemembranepotentialand
suppress responsestoinputsthatoccurat
lowfrequencies.
Voltage-gatedChannel
Modelsofneuronsaselectricalcircuitstounderstandresonance
Theresonantfrequency,orpreferred
frequency, canchangedepending upon
physiological properties oftheneuron.
Forexample:
PassiveChannel
1) Thesizeoftheneuron influences the
capacitance,suchthatlargerneurons
respond slower(worse)tohighfrequencies.
2) Differentvoltage-gatedchannelscounteract
changestothemembranepotentialina
unique manner.
Voltage-gatedChannel
ThisisourFridayactivity!
Modelsofneuronsaselectricalcircuitstounderstandresonance
PassiveChannel
Attherestingmembranepotential,
voltage-gatedchannelsareclosed.
Deviationsfromtherestingmembrane
potentialcanactivatevoltage-gated
channelsthatpromote resonance.
Voltage-gatedChannel
Resonance,dueto
voltage-gatedNa+
channels
Fast-spiking(FS) interneurons inthestriatum:
Resting
membrane
potential
Beattyetal.,J.Neurophysiol., 2015
Howdoweidentifythechannelsthatcauseresonance?
VoltageClamp:
1
2
1.Thevoltageacrossthecellmembraneis
measuredusing intracellularrecording
techniques.
2.Involtage-clamp,acurrentisinjectedto
maintainadesired voltage.
3.Itispossible tomeasurethecurrentthat
isinjectedtoobtainacertainvoltage.
4.Theimpedance ofthecellcanbe
calculatedusing thefollowing equation:
!"#$%&'(! )
Impedance=,-..'/$(0* )
*
Howdoweidentifythechannelsthatcauseresonance?
Adecreaseincurrentamplitude
indicatesresonance
VoltageClamp:
Adesiredvoltagethatisasweep
from1-40Hz
Beattyetal.,J.Neurophysiol., 2015
Beattyetal.,J.Neurophysiol., 2015
Howdoweidentifythechannelsthatcauseresonance?
Cholinergic Interneurons intheStriatum
VoltageClamp:
Placechannel
blockers(e.g.,TTX)
intothebath
Beattyetal.,J.Neurophysiol., 2015
Power(dB)
Frequency (Hz)
Thedorsomedial striatumexhibitsdeltaoscillations:
0.5seconds
AdaptedfromDeCoteau etal.,JNeurophysiol, 2007
Howdoweidentifythechannelsthatcauseresonance?
CurrentClamp:
2
1
1. Incurrentclamp,acurrentisfirst
injectedintothecell.
2. Changestothevoltageacrossthe
membranearemeasured.
!"#$%&'(! )
Impedance=,-..'/$(0* )
*
Howdoweidentifythechannelsthatcauseresonance?
ZAPCurrent:
CurrentClamp:
2
1
Thalamocortical Neurons:
slightlyhyperpolarized ~86mV
AdaptedfromPuil etal.,Journal ofNeurophysiology, 1994
Thethalamusexhibitsdeltaoscillationsduring sleep:
hyperpolarizedneuronsspikeataclocklikedeltaduetohyperpolarizationactivatedcation current(Ih):
Baletal.,J.Neurophys.,1995
McCormickandBal,Ann.Rev.Neurosci.,1997
Wehavediscussedmultiplephysiologicalpropertiesthatcaninfluence
neuralresonance.Howeasydoyouthinkitisforaneurontochangeits
resonantfrequency?