Fold the index fingers so that they touch the inside root of the thumbs.
Straighten the other three fingers of each hand so that they are relaxed and slightly apart.
Place the hands on the knees with the palms facing down.
Relax the hands and arms.
General Benefits
Jnana mudra and chin mudra are simple but important psycho-neural finger locks which make meditation asanas more powerful.
The palms and fingers of the hands have many nerve root endings which constantly emit energy.
When the finger touches the thumb, a circuit is produced which allows the energy that would normally dissipate into the environment to travel back into the body and up to the brain.