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Table 1. 
The most important parameters used in our simulations
SymbolValueDescription
Δt 0.1 ms, 0.01 ms Duration of one time step for network and single-neuron simulations, respectively 
tmax 20 s Total duration of the simulations 
tpulse 4 ms Duration of one light pulse 
λmax 470 nm Wavelength of light, absorption maximum of ChR2/H134R (Williams et al., 2013) 
τChR2 1.3 ms Activation time constant for channels (Nikolic et al., 2009) 
σret 12 ⋅ 10−20 m2 ChR2 retinal absorption cross-section (Williams et al., 2013) 
gChR2 100 fS Single channel conductance (Lin, 2011) 
wloss 1.3 Loss factor accounting for the environment of a channel (Nikolic et al., 2009) 
Γd,0 126.74 1/s Desensitization rate at a potential of −70 mV (Tchumatchenko et al., 2013) 
Γr 8.38 1/s Recovery rate (Tchumatchenko et al., 2013) 
ϵ 0.5 Quantum efficiency for channel opening (Nikolic et al., 2009) 
τm 10 ms Membrane time constant 
τref 3 ms Duration of the refractory period 
gm 0.1 μS Absolute membrane conductance, excluding ChR2 conductances 
Vrev −65 mV Reversal (equilibrium) potential 
Vreset −70 mV Reset potential 
Vth −55 mV Threshold potential to be crossed for spiking 
NChR2 60 000, 300 000 Number of ChR2 channels within one neuron 
σwn 0.01 nA Standard deviation for Gaussian noise in external fluctuations 
I0 0.914576 nA Mean of the external fluctuations (given value is for a single neuron) 
σlight 8 grid units Standard deviation of the spatial Gaussian distribution of light 
NE 3 600 = 60 × 60 Number of neurons in the excitatory population, aligned in a square 
NI 900 Number of neurons in the inhibitory population 
pc 0.005–0.015 Connectivity (probability of connection between two neurons) (Braitenberg & Schüz, 1998; Le Duigou et al., 2014) 
τsyn 5 ms Synaptic time constant, also for external fluctuations 
SymbolValueDescription
Δt 0.1 ms, 0.01 ms Duration of one time step for network and single-neuron simulations, respectively 
tmax 20 s Total duration of the simulations 
tpulse 4 ms Duration of one light pulse 
λmax 470 nm Wavelength of light, absorption maximum of ChR2/H134R (Williams et al., 2013) 
τChR2 1.3 ms Activation time constant for channels (Nikolic et al., 2009) 
σret 12 ⋅ 10−20 m2 ChR2 retinal absorption cross-section (Williams et al., 2013) 
gChR2 100 fS Single channel conductance (Lin, 2011) 
wloss 1.3 Loss factor accounting for the environment of a channel (Nikolic et al., 2009) 
Γd,0 126.74 1/s Desensitization rate at a potential of −70 mV (Tchumatchenko et al., 2013) 
Γr 8.38 1/s Recovery rate (Tchumatchenko et al., 2013) 
ϵ 0.5 Quantum efficiency for channel opening (Nikolic et al., 2009) 
τm 10 ms Membrane time constant 
τref 3 ms Duration of the refractory period 
gm 0.1 μS Absolute membrane conductance, excluding ChR2 conductances 
Vrev −65 mV Reversal (equilibrium) potential 
Vreset −70 mV Reset potential 
Vth −55 mV Threshold potential to be crossed for spiking 
NChR2 60 000, 300 000 Number of ChR2 channels within one neuron 
σwn 0.01 nA Standard deviation for Gaussian noise in external fluctuations 
I0 0.914576 nA Mean of the external fluctuations (given value is for a single neuron) 
σlight 8 grid units Standard deviation of the spatial Gaussian distribution of light 
NE 3 600 = 60 × 60 Number of neurons in the excitatory population, aligned in a square 
NI 900 Number of neurons in the inhibitory population 
pc 0.005–0.015 Connectivity (probability of connection between two neurons) (Braitenberg & Schüz, 1998; Le Duigou et al., 2014) 
τsyn 5 ms Synaptic time constant, also for external fluctuations 

Note. Unless stated otherwise, the values were used as stated in this table.

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