Table 1 Homosynaptic inhibitory plasticity (Hebbian-type learning) and heterosynaptic inhibitory plasticity (non-associative plasticity [60, 70, 184]) characteristics and signal transduction

Characteristics

 Occurs at active synapses)presynaptic activation(

 Occurs at inactive synapses of homosynaptic plasticity

[52, 54,55,56,57,58,59, 62, 68, 69, 185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210]

 Activity-dependent

 Activity-independent

 Input specific

 Not input specific

 Mediates associative modifications of synaptic weights

 Affects a larger population of synapses

 Affects a larger population of synapses

 Weight-dependent for amplitude of changes and direction of changes

 Related to short-term synaptic changes

 Dependent on the distance from the site of induction of homosynaptic plasticity (Mexican hat like profile of amplitude)

 Persists for one or more hours

 Necessary for establishing and fine-tuning neuronal connections

Induction protocols

 Episodes of strong postsynaptic activity at not active synapses

 High or low-frequency stimulation by:

 Afferent tetanization

 Afferent tetanization

 Pairing stimulations

 Pairing stimulations

 Intracellular tetanization

 Intracellular tetanization (purely postsynaptic stimulation)

Plasticity type

 LTP, LTD

 LTP, LTD

Brain areas

 Involves cortical (hippocampus, visual cortex, ventral tegmental area) and subcortical area (deep cerebellar nuclei)

 Involves cortical (neonatal and adult hippocampus, ventral tegmental) area

Receptors

 VGCC

 VGCC

 Both AMPAR and NMDAR

 Both NMDAR-dependent and non-NMDAR- types

 mGluR I

 Both mGlu1 and mGlu₂

 GABA_ARs

 Both GABA_AR and GABA_B R

 D₂R

 D₁R

 5-HT

 α₁ receptors

 α receptors

 M₁AChRs

 nAChRs

 CB₁R

Signaling molecule

 Ca²⁺

Ca²⁺

 IP3

 PLC

  DG

 NO

Signaling pathway

 BDNF/TrkB

 BDNF/TrkB

 cGMP- GC, PKG

 cAMP-PKA

 cAMP⁄PKA

 IP3

 βFGF

 Sp-cAMPS

 ∆FosB,

 PKC

 CREB?