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Table 2 Details of network simulations producing memory activity

From: Stabilization of Memory States by Stochastic Facilitating Synapses

(a) Model summary

Populations

Single population, E

Connectivity

All-to-all

Neuron model

Leaky integrate-and-fire (LIF) with refractoryperiod

Synapse model

Excitatory AMPA + voltage-dependent NMDA, inhibitory GABAconductances − step increase then exponential decay

Input

Independent fixed-rate Poisson spike trains frompopulations of Input cells

Measurements

State transitions times via mean population firingrate

(b) Populations

Name

Elements

Size

E

LIF neurons

N = 8,20,30,40 (static)N = 4,8,12,16 (facilitating)

(c) Connectivity

Name

Source

Target

Pattern

EE

E

E

All-to-all, weight W

(d) Neuron and synapse model

Name

LIF neuron

Type

Leaky integrate-and-fire (LIF) with refractory period, andnoisy Poisson exponential conductance input

Subthreshold dynamics

C m d V d t = g L (V− V L )+ g EE (t)(V− V E )+ g AMPA (t)(V− V E )+ g GABA (t)(V− V I )

EE synaptic conductance dynamics

g EE (t)= g EE max ∑ cells , i s i (t)

τ s d s i d t =− s i (t) between spikes of cell i at times t i ∗ and s i ( t i ∗ + )= s i ( t i ∗ − )+ α ˜ [1− s i ( t i ∗ − )]

Spiking

If V(t)> V t h then

(1) emit spike with time-stamp t ∗

(2) V(t)→ V reset

(f) Input

Type

Description

Poisson generatorsX = AMPA,GABA

τ X d s X d t =− s X (t)+∑δ(t− t X ∗ )

P(t≤ t X ∗ <t+dt)= Ï… X dt; Ï… AMPA = Ï… GABA =800 Hz

(g) Measurements

Transition times

Time for 〈 s i , EE 〉 to transition from below 0.05 to above 0.45( T down ) and from above 0.45 to below 0.05( T up )

(h) LIF neuron parameters

V L

V E

V I

V t h

V reset

g L

g EE max

C m

g AMPA max

g GABA max

Ï„ AMPA

Ï„ GABA

−70 mV

−70 mV

−70 mV

−45 mV

−60 mV

50 nS

30 nS N

0.5 nF

20 nS

20 nS

2 ms

5 ms

(i) Synaptic parameters (EE)

Synapse

Presynaptic Ï„

p 0

Factors

Postsynaptic Ï„ s

α ˜

Static

–

0.5 (M)

–

100 ms

1 − exp(−0.25)

Facilitating

Ï„ F =500ms

0.25 (M)

f F =0.25 (M)

100 ms

1 − exp(−0.25)