That happy feeling you get thinking of cake or getting a promotion--it's all based in your brain's reward system. Until now, scientists who have wanted to know more about this system have focused tons on the release of chemicals like dopamine and serotonin, trying to understand what determines how and when the brain produces them. But once again, the brain has proven itself to be way more complex than we originally imagined.

In a new study from Columbia University, researchers trained mice to find a pole in a darkened room, rewarding them with water. When the researchers looked at brain activity in the trained mice, they found that dendrites in the somatosensory cortex activated when the whiskers of the mice touched the pole. This wasn't surprising, since the somatosensory cortex helps transmit tactile (touch-related) information to other areas of the brain, like the frontal cortex, that can process the data in more advanced ways.

But then the researchers removed the pole and gave the trained mice more water rewards. The researchers got a shock in that the dendrites in the somatosensory cortex still lit up when the mice got the water reward without the pole. In untrained mice, this association wasn't present. That was a big clue that the brains of the trained mice had learned the association.

And it gets even juicier. The researchers assert that there isn't much dopamine in the somatosensory cortex. That implies that there could be another undiscovered neuromodulator--a chemical that regulates neurons--at work in the reward system. And if researchers can find it, potentially they can come up with new ways to address behavior and physiological problems, including issues like depression and addiction. That's critical for the workforce, because depression and anxiety are thought to cost the global economy as much as $1 trillion every year in lost productivity, and a whopping 70 percent of Americans who use illegal drugs are employed.

But the research also suggests that there might be better, novel ways to motivate yourself and keep up good habits. For example, if you wore a fuzzy sweater every time you ate a healthy meal or got paid, you might come to associate the feeling of that clothing with cash or the energy or satiation that good food provides. So wearing the sweater theoretically could help you maintain your diet or get through tasks you normally wouldn't like.

As a final thought, keep in mind that the brain has associations between the different cortices and senses. For example, if something looks gross, we might believe it also tastes bad. And senses are wrapped up in emotional recall and memory. That's why smelling fresh cookies can make you think of afternoons at Grandma's house, and why we use phrases like "a bitter pill to swallow" for things that are tough or unpleasant. This holds for everyone to a degree, although in some people with synesthesia, the crosstalk between the cortices is particularly strong--you might actually "see" sound as color, for example. So while this study focused on touch, it might be that all of the senses could be highly useful in motivation and behavioral change. That's excellent news for leaders and entrepreneurs who need to leave old ways behind to innovate and to take concepts through the long haul.