Affect is mostly prediction

Chapter 4 endnote 53, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

...familiar sensations like your heart beating in your chest, your lungs filling with air, and, most of all, the general pleasant, unpleasant, aroused, and quiescent sensations of affect are not really coming from inside your body. They are driven by simulations in your interoceptive network. [...] My lab has evidence that affect is largely prediction.

As evidence that affect is mostly prediction, my lab performed a meta-analysis of nearly 400 neuroimaging studies, some conducted by our lab and others by other scientists. We found that the body-budgeting regions in the interoceptive network, which issue predictions, including interoceptive predictions, consistently increase in activity when people report strong changes in their affective feelings. Of course, these regions are involved in brain states for thinking, perceiving, and for emotion. This is not a flaw in the logic of reverse inference. It is to be expected, because, whatever your brain is doing (thinking, seeing, feeling, acting), it is also regulating your body-budget.

Is it possible to peer into a person’s brain and see exactly how interoception is transformed into affect? The answer, I’m afraid, is no. This transformation is one of the great mysteries in science and philosophy. It is part of what the philosopher David Chalmers calls the “hard problem of consciousness”: how an experience such as affect, sound, or color “arises from a physical basis” of neurons firing. This question is not likely to be solved anytime soon, but we certainly have ideas, in theory, of how the relevant brain networks might talk to each other. Ideally, we want to observe how conscious experiences materialize from the transactions between neurons, but technically, we’re just not able to do that yet. Still, we can certainly do better than pointing to one spot in the brain and saying “affect is happening here,” because that is really no explanation at all.