Table 2. Model description after [49].
Model summary | |
Populations | 254 populations: 32 areas (Table 1) with eight populations each (area TH: six) |
Topology | — |
Connectivity | area- and population-specific but otherwise random |
Neuron model | leaky integrate-and-fire (LIF), fixed absolute refractory period (voltage clamp) |
Synapse model | exponential postsynaptic currents |
Plasticity | — |
Input | independent homogeneous Poisson spike trains |
Measurements | spiking activity |
Populations | |
Type | Cortex |
Elements | LIF neurons |
Number of populations | 32 areas with eight populations each (area TH: six), two per layer |
Population size | N (area- and population-specific) |
Connectivity | |
Type | source and target neurons drawn randomly with replacement (allowing autapses and multapses) with area- and population-specific connection probabilities |
Weights | fixed, drawn from normal distribution with mean J such that postsynaptic potentials have a mean amplitude of 0.15 mV and standard deviation δJ = 0.1J; 4E to 2/3E increased by factor 2 [36]; weights of inhibitory connections increased by factor g; excitatory weights <0 and inhibitory weights >0 are redrawn; cortico-cortical weights onto excitatory and inhibitory populations increased by factor χ and , respectively |
Delays | fixed, drawn from Gaussian distribution with mean d and standard deviation δd = 0.5d; delays of inhibitory connections factor 2 smaller; delays rounded to the nearest multiple of the simulation step size h = 0.1 ms, inter-area delays drawn from a Gaussian distribution with mean d = s/vt, with distance s and transmission speed vt = 3.5 m/s [46]; and standard deviation δd = d/2, distances determined as the median of the distances between all vertex pairs of the two areas in their surface representation in F99 space, a standard macaque cortical surface included with Caret [47], where the vertex-to-vertex distance is the length of the shortest possible path without crossing the cortical surface [48] (see [35]), delays < 0.1 ms before rounding are redrawn |
Neuron and synapse model | |
Name | LIF neuron |
Type | leaky integrate-and-fire, exponential synaptic current inputs |
Subthreshold dynamics |
if (t > t* + τr) V(t) = Vr else k: neuron index, i: spike index |
Spiking | If V(t−) < θ ∧ V(t+) ≥ θ
1. set t* = t, 2. emit spike with time stamp t* |
Input | |
Type | Background |
Target | LIF neurons |
Description | independent Poisson spikes (for each neuron, fixed rate νext = νbgkext with average external spike rate νbg = 10 spikes/s and number of external inputs per population kext, weight J) |
Measurements | |
Spiking activity |