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

CÉSAR CEBALLOS PhD student Supervisor DR. PROF. ANTÔNIO CARLOS ROQUE Department of Physics DR. PROF. RICARDO LEÃO Department of Physiology University of São Paulo

SUBTHRESHOLD ACTIVE CONDUCTANCES SHAPE THE EPSPS IN CORTICAL NEURONS

EPSPs Purves et al. 2001 http://www.synsys.eu/general-public

( ( ) + V ) + V I I V ( t ) = V ( t ) = 1 - e 1 - e - t t - t t 0 , 0 , å å Subthreshold passive properties g L , k g L , k k k 𝑆 𝑗𝑜 = 𝑒𝑊 𝑒𝐽 −𝑢 𝜐 𝑊 𝑢 = 𝐽 ∗ 𝑆 𝑗𝑜 ∗ 1 − 𝑓 + 𝑊 0 𝜐 = 𝑆 𝑗𝑜 ∗ 𝐷 Sterratt et al. 2011, Purves et al. 2001

( ( ) + V ) + V I I V ( t ) = V ( t ) = 1 - e 1 - e - t t - t t 0 , 0 , å å Subthreshold active properties g L , k g L , k k k What about the subthreshold active conductances ? 𝐽 𝑀𝑓𝑏𝑙 = 𝑕 𝑀𝑓𝑏𝑙 ∗ (𝑊 − 𝐹 𝑠𝑓𝑤 ) 𝐽 𝑏𝑑𝑢𝑗𝑤𝑓 = 𝑕 𝑏𝑑𝑢 ∗ 𝐵(𝑊) ∗ (𝑊 − 𝐹 𝑠𝑓𝑤 ) Activation variable 𝑒𝐽 𝑀𝑓𝑏𝑙 = 𝑕 𝑀𝑓𝑏𝑙 Non voltage-dependent 𝑒𝑊 𝑒𝐽 𝑏𝑑𝑢 𝑒𝑊 = 𝑕 𝑏𝑑𝑢 ∗ 𝑒𝐵(𝑊) Voltage-dependent 𝑒𝑊 Whe need new equations that take into account the active currents ¡¡

Persistent sodium current amplifies the EPSPs 8 -67 7 -77 -82 6 -87 5 -92 -97 4 mV 3 2 1 0 -1 Branco et al. 2016 4950 5000 5050 5100 5150 5200

Intrinsic properties shape the EPSPs Computational simulations of voltage dependence of R in and τ m .

Patch-clamp Patch clamp recording CA1 pyramidal cell Whole cell patch clamp Jaffe & Brown. Journal of Neurophys 1997

Dynamic clamp 𝑛𝑏𝑦 ∗ 𝐵 𝑜𝑏𝑞 ∗ (𝑊 − 𝐹 𝑂𝑏 ) 𝐽 = 𝑕 𝑜𝑏𝑞 ∞ 𝑒𝐵 𝑜𝑏𝑞 = 𝐵 𝑜𝑏𝑞 − 𝐵 𝑜𝑏𝑞 𝑒𝑢 𝜐 1 ∞ 𝐵 𝑜𝑏𝑞 = 1 + 𝑓 (𝑊𝑛+50)/−6

Experimental results - I NaP amplifies the EPSPs http://www.life.umd.edu/grad/mlfsc/zctsim/io Puffer fish nchannel.html

R in 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

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ACKNOWLEDGEMENTS Laboratório de Laboratório de Sistemas Neurofisiologia e Sinapse Neurais SisNe