Presentación de PowerPoint...Neurofisiologia e Sinapse . Title: Presentación de PowerPoint Author:...
Transcript of Presentación de PowerPoint...Neurofisiologia e Sinapse . Title: Presentación de PowerPoint Author:...
University of São Paulo
CÉSAR CEBALLOS PhD student
Supervisor
DR. PROF. ANTÔNIO CARLOS ROQUE Department of Physics
DR. PROF. RICARDO LEÃO Department of Physiology
SUBTHRESHOLD ACTIVE CONDUCTANCES SHAPE THE EPSPS IN CORTICAL
NEURONS
EPSPs
http://www.synsys.eu/general-public Purves et al. 2001
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
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
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
Intrinsic properties shape the EPSPs
Computational simulations of voltage dependence of Rin and τm.
Patch-clamp Patch clamp recording
CA1 pyramidal cell Whole cell patch
clamp
Jaffe & Brown. Journal of Neurophys 1997
Dynamic clamp
𝐼 = 𝑔𝑛𝑎𝑝𝑚𝑎𝑥 ∗ 𝐴𝑛𝑎𝑝 ∗ (𝑉 − 𝐸𝑁𝑎)
𝑑𝐴𝑛𝑎𝑝𝑑𝑡
= 𝐴𝑛𝑎𝑝
∞ − 𝐴𝑛𝑎𝑝𝜏
𝐴𝑛𝑎𝑝∞ =
1
1 + 𝑒(𝑉𝑚+50)/−6
Experimental results - INaP amplifies the EPSPs
http://www.life.umd.edu/grad/mlfsc/zctsim/ionchannel.html
Puffer fish
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
Pdf available in bioRxiv
THANKS
FINANCIAL SUPPORT
ACKNOWLEDGEMENTS
Laboratório de Sistemas Neurais SisNe
Laboratório de Neurofisiologia e Sinapse