Yes. Even though you are required to start drawing down the account, you can continue to add to it through deductible contributions as long as you have net earnings from self-employment. However, you can no longer contribute to a traditional IRA if you had otherwise been able to do so; no contribution is allowed for the year in which you turn age 70-1/2 or any later year. There is no age limit for making Roth IRA contributions as long as you continue to have earned income.
This is generally adjusted gross income increased by certain items such as tax-free foreign earned income. MAGI usually is used to determine phaseouts of certain deductions and credits.