Table 1

Symbol Description Range Value Units

Synaptic dynamics
Depression time constant >0.01–2s.s. s
Facilitation time constant >0.5–2 s.s. s
Resting synaptic release probability <0.09–0.9 s.s.

Neurotransmitter release and time course
Total vesicular glutamate concentration 300–1000 500 mM
Vesicular versus mixing volume ratio 0.005
Glutamate clearance time constant 2–100 25 ms
Efficacy of synaptic transmission 0-1 0.75

Astrocyte GPCR kinetics
Agonist binding rate 0.3 M−1s−1
Agonist unbinding time 0.55 s

IP3R kinetics
Inact. Ca2+ binding rate (with Ca2+ act.)0.04–0.18 0.2 M−1s−1
IP3 binding affinity 0.1–0.15 0.13M
Inact. Ca2+ binding affinity (Ca2+ act.) 1.05 M
IP3 binding affinity (Ca2+ inact.) 0.9434 M
Act. Ca2+ binding affinity 0.08 M

Calcium fluxes
ER-to-cytoplasm volume ratio 0.4–0.7 0.18
Total ER Ca2+ content 3–5 2 M
Max. Ca2+ leak rate 0.05–0.1 0.1 s−1
Max. Ca2+ release rate by IP3Rs >6 6 s−1
Ca2+ affinity of SERCA pumps 0.05–0.1 0.05 M
Max. Ca2+ uptake rate 0.4–1.3 0.9 M s−1

IP3 production
Max. rate of IP3 production by PLC0.05–2 1 M s−1
Ca2+ affinity of PLC0.1–1 0.5 M
Inhibiting IP3 affinity of PLC1–1.5 1 M
Max. rate of IP3 production by PLC<0.8 0.05 M s−1

IP3 degradation
Max. rate of IP3 degradation by IP-5P>0.05–0.25 0.1s−1
Ca2+ affinity of IP3-3K 0.4–0.5 0.5M
IP3 affinity of IP3-3K 0.7–1 1 M
Max. rate of IP3 degradation by IP3-3K >0.6 4.5M s−1

Gliotransmitter release and time course
Ca2+ threshold for exocytosis 0.15–0.8 0.5 M
Glutamate recycling time constant 0.003–1.5 1.66 s
Resting glutamate release probability <0.9 0.6
Vesicular versus mixing volume ratio 6.5 ⋅ 10−4
Glutamate clearance time constant ≤300 200 ms

Presynaptic receptors
Activation rate >0.3 1.5 M−1s−1
Inactivation time constant >30–180 120 s
Gliotransmission type 0-1 s.s.

Postsynaptic neuron
Membrane time constant 20–70 40 ms
Refractory period 1–5 2 ms
Resting potential −78.2–−54.8 −60 mV
Firing threshold −55–−51 −55 mV
Reset potential −58–−53 −57 mV
Peak AP amplitude 29.8–41.2 30 mV
Input resistance 60–150 s.s. M

Postsynaptic currents
EPSC rise time 0.4–0.6 0.5 ms
EPSC decay time 2.7–11.6 10 ms
Synaptic efficacy 4.3
EPSP amplitude 0.5–7.5 2 mV

Slow inward currents
SIC rise time 20–70 20 ms
SIC decay time 100–800 600ms
SIC efficacy 68
SIC amplitude 1–10 4.5 mV

Spike-timing-dependent plasticity
NMDAR-mediated Ca2+ increase per AP 1.0
NMDAR Ca2+ rise time 10 ms
NMDAR Ca2+ decay time 30 ms
Synaptic weight 39.7
VDCC-mediated Ca2+ increase per AP 2.5
VDCC Ca2+ rise time 2 ms
VDCC Ca2+ decay time 12 ms
SIC-mediated Ca2+ increase per AP 1.0
SIC Ca2+ rise time 5 ms
SIC Ca2+ decay time 100 ms
SIC weight 10.6
Amplification of NMDAR-mediated Ca2+4
LTD threshold 1.0
LTP threshold 2.2
LTD learning rate 0.57 s−1
LTP learning rate 2.32 s−1
Boundary between UP/DOWN states 0.5
Decay time of synaptic change 1.5 s
Noise amplitude 0.1
Fraction of synapses in the DOWN state0.5
UP/DOWN Synaptic strength ratio 4