Turkish voters are set to cast their ballots in a referendum on a new draft constitution on 16 April.

A 'yes' vote would significantly increase the powers of Turkish President Recep Tayyip Erdogan and turn the country from a parliamentary to a presidential republic.

Some critics of Erdogan have found their opposition to his policies harshly punished.

The BBC's Mark Lowen met 82-year-old Oget Oktem Tanor, Turkey's first neuropsychologist and an emeritus professor of Istanbul University.

She fell foul of authorities after signing a petition calling on the government to cease its military operations in Kurdish areas of the country.