Using midi-keyboard to play with two instruments

Hello, I would appreciate any help with the following manner:
I use M-Audio keyrig49 USB midi-keyboard plugged to my PC, with focusrite scarlett 2i2 external sound driver, running cubase 5.

As for now, I can use instrument-tracks I’ve placed (in example, taken from Halion) to play live with the midi-keyboard.
I would like to assign two intrument tracks to the keyboard, such that the lower octaves will operate instrument_1 while the higher octaves from the same midi-keyboard will trigger the intrument_2.