[levocardia]

If you know DNNs, you'll find the introduction of splines in Semiparametric Regression in R very intuitive - splines are introduced using what the authors call a "truncated line basis" but you already know it as the RELU function, just with a bias. Indeed, even the penalization of splines will look extremely familiar: it's basically just L2 regularization to induce smoothness.

You might also enjoy reading the "Neural Additive Model" paper from Hinton's lab, which is basically GAMs using a separate DNN as a "spline basis" for each input variable.