New Scientist magazine said the study indicates when someone first "falls in love," there is heightened activity in dopamine-rich brain regions associated with motivation and reward.
But Rutgers University research anthropologist Helen Fisher said regions of the brain associated with emotion are not activated until more mature phases of a relationship begin.
New Scientist said Fisher and her colleagues recruited seven male and 10 female volunteers who claimed to be madly in love. They asked them to look at pictures of either their loved one or another familiar person while inside a functional MRI scanner.
Her studies showed that during the earlier, intense phases of a relationship there is concentrated activity in the so-called right caudate nucleus and right ventral tegmentum, whereas the insular cortex and parts of the anterior cingulate cortex, where emotions are based, are not activated until later in a relationship.
The research was presented during this week's meeting of the Society for Neuroscience in New Orleans.