Scientists have traced the lure of chocolate to a part of the brain called neostriatum, and its production of a natural, opium-like chemical, enkephalin.
The findings reveal a surprising extension of the neostriatum's role, as Alexandra DiFeliceantonio, from the University of Michigan, Ann Arbor and her team made the discovery.
DiFeliceantonio notes that the brain region had primarily been linked to movement. And there is reason to expect that the findings in rats can tell us a lot about our own binge-eating tendencies, the journal "Current Biology" reports.
The researchers also found that enkephalin surged when rats began to eat the candy-coated morsels, according to a Michigan statement.
It's not that enkephalins or similar drugs make the rats like the chocolates more, the researchers say, but rather that the brain chemicals increase their desire and impulse to eat them.
"This means that the brain has more extensive systems to make individuals want to over consume rewards than previously thought," said DiFeliceantonio. "It may be one reason why over consumption is a problem today."
"The same brain area we tested here is active when obese people see foods and when drug addicts see drug scenes," she says.
"It seems likely that our enkephalin findings in rats mean that this neurotransmitter may drive some forms of over consumption and addiction in people," she said.