How to put in Voltage Dependent Current Source in LTSpice
A dependent source is dependent on either a voltage or current. This lets us make feedback loops and other interesting circuits. 

With a voltage controlled current source (VCCS) the control voltage comes from voltage source, the inputs to the source draws no current and the current from the source is based on this voltage. In this case the voltage is controlled from the differential voltage across the resistor. Like this: