CSAR CEBALLOS PhD student Supervisor DR. PROF. ANTNIO CARLOS ROQUE - - PowerPoint PPT Presentation

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 𝑆𝑗𝑜 = 𝑒𝑊

𝑒𝐽

V(t) = I gL,k

k

å

1-e

• t t

( )+V

0,

V(t) = I gL,k

k

å

1-e

• t t

( )+V

0,

𝑊 𝑢 = 𝐽 ∗ 𝑆𝑗𝑜 ∗ 1 − 𝑓

−𝑢 𝜐

+ 𝑊 𝜐 = 𝑆𝑗𝑜 ∗ 𝐷

Subthreshold active properties

V(t) = I gL,k

k

å

1-e

• t t

( )+V

0,

V(t) = I gL,k

k

å

1-e

• t t

( )+V

0,

What about the subthreshold active conductances ?

𝐽𝑀𝑓𝑏𝑙 = 𝑕𝑀𝑓𝑏𝑙 ∗ (𝑊 − 𝐹𝑠𝑓𝑤) 𝐽𝑏𝑑𝑢𝑗𝑤𝑓 = 𝑕𝑏𝑑𝑢 ∗ 𝐵(𝑊) ∗ (𝑊 − 𝐹𝑠𝑓𝑤) 𝑒𝐽𝑀𝑓𝑏𝑙 𝑒𝑊 = 𝑕𝑀𝑓𝑏𝑙 Non voltage-dependent 𝑒𝐽𝑏𝑑𝑢 𝑒𝑊 = 𝑕𝑏𝑑𝑢 ∗ 𝑒𝐵(𝑊) 𝑒𝑊 Voltage-dependent

Whe need new equations that take into account the active currents ¡¡

Activation variable

4950 5000 5050 5100 5150 5200

• 1

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

• f Neurophys 1997

Dynamic clamp

𝐽 = 𝑕𝑜𝑏𝑞

𝑛𝑏𝑦 ∗ 𝐵𝑜𝑏𝑞 ∗ (𝑊 − 𝐹𝑂𝑏)

𝑒𝐵𝑜𝑏𝑞 𝑒𝑢 = 𝐵𝑜𝑏𝑞

∞

− 𝐵𝑜𝑏𝑞 𝜐 𝐵𝑜𝑏𝑞

∞

= 1 1 + 𝑓(𝑊𝑛+50)/−6

Experimental results - INaP amplifies the EPSPs http://www.life.umd.edu/grad/mlfsc/zctsim/io nchannel.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