Table 1 The factors affecting the direction of plastic changes in synapses

1

Theta burst stimulation (TBS)

In synaptic inputs that received TBS

In other synaptic inputs without TBS

[23]

2

Frequency of tetanization

High >  = 20 Hz

Low <  = 3Hz

[64, 65]

3

Timing of the pre- to postsynaptic activity

10–20 ms before the postsynaptic cell

10–20 ms after the postsynaptic cell

[66, 67]

4

Intracellular Ca²⁺ concentration

Strong enhancement of [Ca²⁺]_in

Moderate enhancement of [Ca²⁺]_in

[27, 68, 69]

5

Pre-synaptic release probability

Lower initial release probability (high original PPR)

Higher release probability (low original PPR)

[22, 28, 71, 70, 72]

6

Sign of Hom-plasticity (LTP or LTD)

Het-LTP or Het-LTD at adjacent synapse

Het-LTD or Het-LTP at more distant inputs

[30, 54, 56]

7

Spatial distribution

LTP at more distant inputs

LTD at adjacent distances

[22]

8

History-dependency of synaptic inputs

Prior depression

Prior potentiation

[73, 74, 75, 76]

9

Firing of a third modulatory interneuron

Excitatory third neuron

Inhibitory third neuron

[77, 78, 79]