Science has identified what any parent might have guessed: Teenagers' brains contain a wellspring of back talk and attitude.

Blame the amygdala, a brain structure that's a center of emotional drive, which is larger than average in teenagers who are most prone to arguing with their parents.

Researchers are trying to figure out how brain changes during the teen years contribute to emotional maturity — and illnesses such as depression.

Using video, researchers counted the teens' every contemptuous and belligerent facial expression, and every disapproving, threatening and argumentative utterance after setting up arguments — as if that were necessary — between 137 teenagers and their parents in Australia.

They matched the attitude with scans of the teens' brains.

"Parents are really good at eliciting emotional reactions from their children," said study co-author Lisa Sheeber.

In recent years, neuroscientists have discovered that the brain undergoes astounding reconstruction during adolescence. Parts in charge of reasoning and problem-solving are among the last to mature, leaving younger teens somewhat at the mercy of emotionally charged brain centers.