I think I’ve spotted an actual desiring machine in the field! Scientific American:

Splenda is not satisfying—at least according to the brain. A new study found that even when the palate cannot distinguish between the artificial sweetener and sugar, our brain knows the difference.

At the University of California, San Diego, 12 women underwent functional MRI while sipping water sweetened with either real sugar (sucrose) or Splenda (sucralose). Sweeteners, real or artificial, bind to and stimulate receptors on the taste buds, which then signal the brain via the cranial nerve. Although both sugar and Splenda initiate the same taste and pleasure pathways in the brain—and the subjects could not tell the solutions apart—the sugar activated pleasure-related brain regions more extensively than the Splenda did. In particular, “the real thing, the sugar, elicits a much greater response in the insula,” says the study’s lead author, psych­ia­trist Guido Frank, now at the Univer­sity of Colorado at Denver. The insula, involved with taste, also plays a role in enjoyment by connecting regions in the reward system that encode the sens­a­tion of pleasantness.

“Looking at the connection between the taste areas, Splenda is stronger,” Frank says. He suggests that when we taste Splenda, the reward system becomes activated but not satiated. “Our hypoth­esis is that Splenda has less of a feedback mechanism to stop the craving, to get satisfied.”

“The reward system becomes activated but not satiated…” What could go wrong?  Read more