Source : Webster's Revised Unabridged Dictionary (1913)

Differentially \Dif`fer*en"tial*ly\, adv.
   In the way of differentiation.

Source : WordNet®

differentially
     adv : in a differential manner; "Hubel and Wiesel have found cells
           that respond differentially according to the direction
           in which a stimulus is moved across the retina"