presentación de powerpoint...neurofisiologia e sinapse . title: presentación de powerpoint author:...
TRANSCRIPT
![Page 1: Presentación de PowerPoint...Neurofisiologia e Sinapse . Title: Presentación de PowerPoint Author: hp Created Date: 11/20/2016 8:55:47 PM](https://reader036.vdocuments.us/reader036/viewer/2022062605/5fca52a8bbaed813914ff086/html5/thumbnails/1.jpg)
University of São Paulo
CÉSAR CEBALLOS PhD student
Supervisor
DR. PROF. ANTÔNIO CARLOS ROQUE Department of Physics
DR. PROF. RICARDO LEÃO Department of Physiology
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SUBTHRESHOLD ACTIVE CONDUCTANCES SHAPE THE EPSPS IN CORTICAL
NEURONS
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EPSPs
http://www.synsys.eu/general-public Purves et al. 2001
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Subthreshold passive properties
Sterratt et al. 2011, Purves et al. 2001
𝑅𝑖𝑛 = 𝑑𝑉
𝑑𝐼
V(t) =I
gL,k
k
å1- e-t t( ) +V0,V(t) =
I
gL,k
k
å1- e-t t( ) +V0,
𝑉 𝑡 = 𝐼 ∗ 𝑅𝑖𝑛 ∗ 1 − 𝑒−𝑡
𝜏 + 𝑉0
𝜏 = 𝑅𝑖𝑛 ∗ 𝐶
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Subthreshold active properties V(t) =
I
gL,k
k
å1- e-t t( ) +V0,V(t) =
I
gL,k
k
å1- e-t t( ) +V0,
What about the subthreshold active conductances ?
𝐼𝐿𝑒𝑎𝑘 = 𝑔𝐿𝑒𝑎𝑘 ∗ (𝑉 − 𝐸𝑟𝑒𝑣)
𝐼𝑎𝑐𝑡𝑖𝑣𝑒 = 𝑔𝑎𝑐𝑡 ∗ 𝐴(𝑉) ∗ (𝑉 − 𝐸𝑟𝑒𝑣)
𝑑𝐼𝐿𝑒𝑎𝑘𝑑𝑉
= 𝑔𝐿𝑒𝑎𝑘 Non voltage-dependent
𝑑𝐼𝑎𝑐𝑡𝑑𝑉
= 𝑔𝑎𝑐𝑡 ∗𝑑𝐴(𝑉)
𝑑𝑉
Voltage-dependent
Whe need new equations that take into account the active currents ¡¡
Activation variable
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4950 5000 5050 5100 5150 5200-1
0
1
2
3
4
5
6
7
8
mV
-67
-77
-82
-87
-92
-97
Branco et al. 2016
Persistent sodium current amplifies the EPSPs
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Intrinsic properties shape the EPSPs
Computational simulations of voltage dependence of Rin and τm.
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Patch-clamp Patch clamp recording
CA1 pyramidal cell Whole cell patch
clamp
Jaffe & Brown. Journal of Neurophys 1997
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Dynamic clamp
𝐼 = 𝑔𝑛𝑎𝑝𝑚𝑎𝑥 ∗ 𝐴𝑛𝑎𝑝 ∗ (𝑉 − 𝐸𝑁𝑎)
𝑑𝐴𝑛𝑎𝑝𝑑𝑡
= 𝐴𝑛𝑎𝑝
∞ − 𝐴𝑛𝑎𝑝𝜏
𝐴𝑛𝑎𝑝∞ =
1
1 + 𝑒(𝑉𝑚+50)/−6
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Experimental results - INaP amplifies the EPSPs
http://www.life.umd.edu/grad/mlfsc/zctsim/ionchannel.html
Puffer fish
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Rin and τ are voltage dependent
The persistent sodium current increases the input resistance and membrane time constant which amplifies the EPSPs in cortical neurons
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Pdf available in bioRxiv
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THANKS
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FINANCIAL SUPPORT
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ACKNOWLEDGEMENTS
Laboratório de Sistemas Neurais SisNe
Laboratório de Neurofisiologia e Sinapse