It is very odd when you say that bitcoin acts as central bank. Thats very misinterpreted statement about the bitcoin. It is decentralised one by nature and neither any trades, transactions, investments of any other currency (altcoins) depends on it or gets regulated via it. So I am pretty sure that its wrong statement about it and should be corrected. Bitcoin itself is a sphere who has its own economic characteristic. They change, adapt according to the investors, public use, limits, demand etc and thus creates its own economic outputs and inputs. May be there is no currency(ies) which are inter-related here for their economic function, at least I would think that way only.