LTspice dc sweep for hysteretic device

Hi,

I am trying to obtain the I-V curve of a device with hysteretic behavior. That is, when the voltage goes from high to low and from low to high, the current curve is not overlapped. I wrote the following dc analysis condition in my code:

.DC Vtest -2V, 2V, 0.1V

But this will only sweep from -2V to 2V. How should I write this line so that I can also see the current change when voltage sweep backwards (from 2V to -2V)?

Thanks in advance,
-Guangyu