It is always exciting when a specific behavior can be directly linked to particular neurons.a paper came out from the Sternson lab at Janelia Farm explaining that when certain neurons (AgRP) in the mouse hypothalamus were stimulated with light, the mouse would spontaneously start eating. The mouse would pretty much keep eating (except for water breaks) until the stimulation stopped. What's even more interesting is that the neurons right next to these (POMC) had pretty much the opposite effect. When they were stimulated, the mouse didn't eat much and over time lost weight.
This may seem like the basis for the next miracle diet, find a way to stimulate POMC neurons and suppress AgRP neurons, right?
Unfortunately it's not that easy. There is a lot more work to be done. In fact this is just the beginning of understanding the hunger circuit. Sure stimulating the neurons directly with light causes eating, but what naturally stimulates those neurons?
Neurons fire when they recieve signals from other neurons which in turn fire when they receive signals from other neurons.... and so forth in a never ending chain.
So, where does the 'must eat' signal ultimately come from?
where is the beginning of that neural chain?
We will investigate this a little more in Part 2, when we look at a follow up paper.
Aponte Y, Atasoy D, & Sternson SM (2011). AGRP neurons are sufficient to orchestrate feeding behavior rapidly and without training. Nature neuroscience, 14 (3), 351-5 PMID: 21209617