Last year, DiCarlo’s team published results that took on both the opacity of deep nets and their alleged inability to generalize. The researchers used a version of AlexNet to model the ventral visual stream of macaques and figured out the correspondences between the artificial neuron units and neural sites in the monkeys’ V4 area. Then, using the computational model, they synthesized images that they predicted would elicit unnaturally high levels of activity in the monkey neurons. In one experiment, when these “unnatural” images were shown to monkeys, they elevated the activity of 68% of the neural sites beyond their usual levels; in another, the images drove up activity in one neuron while suppressing it in nearby neurons. Both results were predicted by the neural-net model.

To the researchers, these results suggest that the deep nets do generalize to brains and are not entirely unfathomable. “However, we acknowledge that … many other notions of ‘understanding’ remain to be explored to see whether and how these models add value,” they wrote.

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