1.   According to Davidson, finding happiness may mean going no further than your very own forehead - the left prefrontal cortex of your brain, to be exact.

2.   He says that some studies have found that antidepression drugs increase left prefrontal cortex activity, although there is no research yet on how long the effects last.

3.   People blessed with effervescent left prefrontal cortices are much more likely to be smiling.

4.   The left prefrontal cortices of self-described happy people were bursting with nerve-cell activity while those who were depressed had more active right prefrontal lobes.