A mother looks at her smiling baby and every tune of her soul is singing a sweet and happy tune... we all know that. However new scientific research indicates there is more to it:

A new study shows seeing her baby's smile lights up the reward center in a mother's brain. Researchers say understanding that reaction may help explain that special mother-child bond and determine why it sometimes goes wrong...

Researchers found that when the mothers saw happy images of their own baby, activation increased in areas of the brain associated with reward and the neurotransmitter dopamine compared with seeing images of other babies.

"These are areas that have been activated in other experiments associated with drug addiction," says Strathearn. "It may be that seeing your own baby's smiling face is like a 'natural high.'"

Read more at the WebMD: Baby's Smile a Natural High for Mom - Looking at Baby’s Smile Triggers Reward Center in Mom’s Brain