Extension to

Salaam

What does "extension" mean in the following paragraph please? Can it be interpreted as: "another step to confirm" the notion of...? Or does it simply mean: "It extends the notion of..."?

“This is a nice extension to the notion of dopamine coding of reward prediction error,” wrote Wolfram Schultz, a pioneer in dopamine neuron behavior who wasn’t involved in the study, in an email. “It is amazing how this very simple dopamine response predictably follows intuitive patterns of basic biological learning processes that are now becoming a component of AI.”