cribed ▁to ▁an ▁al loster ic ▁re ceptor ▁change . ▁Kar cz mar ▁pione ered ▁also ▁the ▁studies ▁of ▁the ▁struct ural ▁nature ▁of ▁central ▁ch ol iner g ic ▁re cept ors ▁by ▁demonstr ating ▁the ▁struct ural ▁similarity ▁between ▁peri pher al ▁and ▁central ▁mus car in ic ▁re cept ors . ▁ ▁With ▁Ky oz o ▁K ok ets u , ▁Sy og oro ▁N ishi ▁and ▁N ae ▁Dun ▁Kar cz mar ▁identified ▁in ▁the ▁ 1 9 5 0 s ▁and ▁ 1 9 6 0 s ▁the ▁three ▁gang l ionic ▁re ceptor ▁sites ▁( nic ot in ic , ▁mus car in ic ▁and ▁pe pt ider g ic ) ▁and ▁their ▁potential s ; ▁they ▁described ▁their ▁ion ic ▁mechan isms ▁and ▁the ▁contribution ▁of ▁second ▁mess engers ▁to ▁gang l ionic ▁transmission . ▁ ▁Since ▁the ▁ 1 9 6 0 s , ▁Kar cz mar ▁contributed ▁to ▁establish ing ▁the ▁pre - em inent ▁role ▁of ▁the ▁central ▁ch ol iner g ic ▁system ▁in ▁functions ▁such ▁as ▁resp iration , ▁behav iors ▁such ▁as ▁ag gression , ▁per ception s ▁such ▁as ▁n oc ice ption , ▁learning , ▁add iction , ▁ob session ▁and ▁fix ation , ▁and ▁sexual ▁and ▁motor ▁activity , ▁and ▁in ▁phen omena ▁such ▁as ▁se iz ures , ▁E EG ▁rh yth ms , ▁par ado x ical ▁sleep , ▁and ▁behavior al ▁and ▁E EG ▁alert ing ; ▁and ▁he ▁and ▁his ▁associ ates ▁provided