Investment of the cultural endowment fund must be under the supervision of the state investment board in accordance with chapter 21-10. Funds will be expended from the cultural endowment fund only to the limits of accrued interest on state general fund appropriations and other public and private funds received. The expenditure of endowment funds must occur at the direction of the North Dakota council on the arts. The council may seek the counsel and assistance of a group or groups of private citizens of the council’s choosing to aid it in arriving at expenditure decisions when private funds are involved. Section 54-54-06 applies to private donations to the cultural endowment fund; provided, that gifts, donations, and bequests can be dedicated as principal of the fund in perpetuity or for a term of years, in which case only the income earned as a result of investment of those funds can be expended pursuant to section 54-54-08.1 and this section.