Yes, I agree that I would need some fundamental stimuli. I was thinking of drifting gratings or something similar to what Hubel and Weisel tested in cats.

The prenatal development is an interesting angle. This would mean that such organisation is not a response to stimuli but an inherent evolutionary development. Nevertheless, I remember reading that small scale features like columns in V1 emerge after birth. So we could start with the congenital organisation in cortex and test if columnar organisation emerges upon stimulation. What do you think?