▁distinct ▁forms ▁of ▁heter os yn apt ic ▁pl astic ity ▁have ▁been ▁found ▁in ▁a ▁variety ▁of ▁brain ▁regions ▁and ▁organ isms . ▁ ▁These ▁different ▁forms ▁of ▁heter os yn apt ic ▁pl astic ity ▁contribute ▁to ▁a ▁variety ▁of ▁neural ▁processes ▁including ▁associ ative ▁learning , ▁the ▁development ▁of ▁neural ▁circ uits , ▁and ▁home ost asis ▁of ▁syn apt ic ▁input . ▁ ▁Home ost atic ▁role ▁ ▁H eter os yn apt ic ▁pl astic ity ▁may ▁play ▁an ▁important ▁home ost atic ▁role ▁in ▁neural ▁pl astic ity ▁by ▁normal izing ▁or ▁limit ing ▁the ▁total ▁change ▁of ▁syn apt ic ▁input ▁during ▁on going ▁Heb bian ▁pl astic ity . ▁ ▁Heb bian ▁pl astic ity , ▁an ▁u bi quit ous ▁form ▁of ▁hom os yn apt ic , ▁associ ative ▁pl astic ity , ▁is ▁believed ▁to ▁under lie ▁learning ▁and ▁memory . ▁Moreover , ▁Heb bian ▁pl astic ity ▁is ▁induced ▁by ▁and ▁ampl ifies ▁correl ations ▁in ▁neural ▁circ uits ▁which ▁creates ▁a ▁positive ▁feedback ▁loop ▁and ▁rend ers ▁neural ▁circ uits ▁un stable . ▁To ▁avoid ▁this ▁inst ability ▁Heb bian ▁pl astic ity ▁needs ▁to ▁be ▁const rained , ▁for ▁instance ▁by ▁the ▁conservation ▁of ▁the ▁total ▁amount ▁of ▁syn apt ic ▁input . ▁This ▁role ▁ ▁is ▁believed ▁to ▁be ▁ful filled ▁by ▁a ▁divers ity ▁of ▁home ost atic ▁mechan isms . ▁ ▁However , ▁to ▁effectively ▁stabil ize ▁Heb bian ▁pl astic ity , ▁which ▁can ▁be