I don't get you. You mean your palm or what? I still keep the same backhand grip which means my thumb is at the edge of the racket. Just that before striking the shuttle, I grip it tightly.
Your grip will be different depending on whether the shuttle is in front of you, level with you, or behind you. You can see an example of backgrand grip tightening, using the thumb grip, on my grip principles page. Look at the section "Badminton grip tightening".