Whenever we smile , nerves and muscles may transmit messages that turn on happiness centers in the brain , laird speculates . " The bottom line is that a smile doesn 't cost anything and may do you good . "
And david laird , of america 's department of agriculture , showed that biochar even helped the rich soil of america 's midwest by reducing the leaching from it of a number of nutrients , including nitrate , phosphate and potassium .
In experiments at clark university , psychologist james laird , phd , hooked volunteers up to sham electrodes and instructed them to contract and relax specific facial muscles , so they were , in effect , smiling for no reason at all .
Whenever we smile , nerves and muscles may transmit messages that turn on happiness centers in the brain , laird speculates .
每当我们微笑时,神经和肌肉就会传递信息使大脑的快乐中心兴奋,莱尔德猜测说。
Within a year , laird and eastman were approached with a toy license , which was followed by a cartoon television series and three live-action feature films over the course of nine years .