NEW ORLEANS (AP) - When you're in love, your eyes light up, your face

lights

up - and, apparently, so do four tiny bits of your brain.

"It is the common denominator of romantic love," said Andreas

Bartels, a

doctoral student at University College London who presented his

research at

the Society for Neuroscience.

He used functional MRI, a brain scan showing the brain over time

instead of

a still picture, to examine 17 students who said they were truly in

love -

and whose statements were backed up by psychological tests.

When the subjects were shown photographs of their sweethearts,

different

areas of the image lit up - indicating higher blood flow - than when

they

were shown photographs of friends. The friends were the same sex as

the

sweethearts, and were people the subjects had known about as long.

Anywhere from six to 20 parts of the brain showed increased activity,

varying from person to person, but only a common denominator of four

were

found in all 11 women and six men, Bartels said.

In addition, he said, looking at pictures of their loved one reduced

activity in three larger areas of the brain known to be active when

people

are upset or depressed.

The images are clear, but the emotions aren't, said Dr. Marcus

Raichle of

Washington University, who attended Bartels' presentation. The brain

scan

images do show a common reaction, he said. "The question is, what is

the state he is eliciting?"

While there are plenty of rating scales for anger and fear, Raichle

said

love has not been as thoroughly studied. Scales like those for the

negative

emotions are needed for love, he said.

Bartels said the lack of previous research was what interested

him. "Vast

numbers of studies have been done on negative emotions - fear,

sadness,

anger, disgust. We decided to tease out a positive emotion."

In the study, Bartels said the students were asked what they felt

when they

looked at the pictures; to be sure they were feeling romantic love.

The

areas of the brain that became active were near areas, which also

become

active when someone is feeling simple lust, but they are not the same

areas,

he said.

The areas which lit up were part of the anterior cingulate cortex,

which is

near the brain's midline, and, deeper in the brain, the middle insula

and

parts of the putamen and caudate nucleus.

Raichle was at the news conference to discuss his own work, on

emotion and

memory. He used the same type of functional MRI brain scans to

examine 18

people who were asked to count the number of people in photographs.

Some of the pictures were neutral - the focus was things like

furniture.

Others were designed to create very negative emotions, such as

pictures of

mutilated bodies.

People were slower and less accurate when looking at the negative

pictures

and parts of the brain associated with emotion became more active,

while

parts associated with thought grew less so, he said.