apt ic ▁pl astic ity . ▁ ▁Ch anges ▁in ▁pl astic ity ▁during ▁development ▁Early ▁in ▁development , ▁syn apt ic ▁connections ▁are ▁not ▁input - specific , ▁most ▁likely ▁because ▁of ▁Ca 2 + ▁sp illo ver ▁( i . e . ▁Ca 2 + ▁is ▁not ▁restricted ▁to ▁d end rit es ▁specifically ▁activ ated ). ▁This ▁sp illo ver ▁represents ▁another ▁mechanism ▁of ▁heter os yn apt ic ▁change ▁in ▁pl astic ity . ▁Network s ▁are ▁later ▁ref ined ▁by ▁input - specific ▁pl astic ity , ▁which ▁allows ▁for ▁the ▁elim ination ▁of ▁connections ▁that ▁are ▁not ▁specifically ▁stim ulated . ▁As ▁neur onal ▁circ uits ▁m ature , ▁it ▁is ▁likely ▁that ▁the ▁concentration ▁of ▁Ca 2 + ▁binding ▁prote ins ▁increases , ▁which ▁prevents ▁Ca 2 + ▁from ▁diff using ▁to ▁other ▁sites . ▁ ▁In cre ases ▁in ▁local ized ▁Ca 2 + ▁lead ▁to ▁A MP AR s ▁inserted ▁into ▁the ▁memb rane . ▁This ▁increase ▁in ▁A MP A ▁density ▁in ▁the ▁posts yn apt ic ▁memb rane ▁increases ▁enables ▁N MD AR s ▁to ▁be ▁functional , ▁allowing ▁more ▁Ca 2 + ▁to ▁enter ▁the ▁cell . ▁N MD AR ▁sub un its ▁also ▁change ▁as ▁neur ons ▁m ature , ▁increasing ▁the ▁re ceptor ' s ▁conduct ance ▁property . ▁These ▁mechan isms ▁facil itate ▁Ca 2 + ▁location ▁restriction , ▁and ▁thus ▁specific ity , ▁as ▁an ▁organ ism ▁progress es ▁through ▁development . ▁ ▁Syn apt ic ▁S