![hedonic gloss hedonic gloss](http://image.slideserve.com/479750/assessing-my-simple-pleasure-n.jpg)
One special neural channel, called nanchung, is tuned to the detection of dry air. They have two specialized neurons devoted to that purpose in sensory hairs in their antennae’s third segment. Flies don’t have noses, so they don’t literally sniff, but it’s known that they can detect humidity differences with their antennae. If Waddell’s flies had spent the preceding day in a normal vial with the usual moist fly food (they are fond of molasses), most of them sniffed the air and walked into the dry tube. The fly stands before the vast mouths of two glass tubes. The maze confronts a fly with what is known as a choice point-a fork in the road. For their experiments, Waddell and his team used a variation on the simple T-maze, which is a standard piece of apparatus in mind-of-the-fly laboratories. In their new paper, the researchers looked at the way flies respond to thirst, which hasn’t been studied much most of the work in flies has focussed on hunger. By studying the anatomy of reward in the fly, Waddell and his colleagues hope to shed some light on human yearnings. But it’s remarkably similar to ours in certain fundamental respects. Its neural anatomy is very different from ours in the details-flies and mammals are separated by hundreds of millions of years of evolution. There are about a hundred thousand neurons in the fruit-fly brain, versus nearly ninety billion in the human brain. Drosophila melanogaster has been a tiny laboratory workhorse for more than a century, ever since it helped prove the theory of chromosomal inheritance. The group, which is led by Scott Waddell, studies rewards, motivation, and memory in the comparatively simple brain of the fruit fly. The latest issue of the journal Nature Neuroscience includes an article by a group of researchers from the Centre for Neural Circuits and Behaviour, at Oxford. But, amid all the neural activity generated by such broad categories of behavior as liking, wanting, and learning, it’s hard to figure out where it all starts in the mammalian brain. Dopamine, a hormone secreted by certain neurons, is known to play a major role in pleasure and reward. In one recent review of the literature, Berridge notes reward-related activity in the orbitofrontal cortex, the anterior cingulate, and the insula, as well as in deeper, subcortical structures, such as the nucleus accumbens, the ventral pallidum, the ventral tegmentum, the amygdala, and some of the dopamine pathways between them. They get lost in whole South Sea archipelagoes of hot spots. So many brain areas light up in response to a sweet taste, a hit of intravenous cocaine, a jackpot win, or a subliminal glimpse of a smiley face that researchers can’t make much sense of what’s going on. But when scientists go hunting for these hot spots, using neural recordings and neuroimaging studies, they find them all over the place. Presumably, there are dedicated places in the brain-Berridge calls them “hedonic hot spots”-where the gloss of pleasure is painted on, where a certain sheen and glimmer is cast over life’s rewards. In other words, the experience of reward is generated from within as well as from without. ‘Wanting’ and ‘liking’ reactions are actively generated by neural systems that paint the desire or pleasure onto the sensation**-**as a sort of gloss painted on the sight, smell or taste.” “Our fundamental starting point,” he has written, “is that the temptation and pleasure of sweet, fatty, or salty foods arise actively within the brain, not just passively from physical properties of foods themselves. In the science of reward, Berridge’s framework is both influential and controversial.