Given the amount of time that many people waste online, you might suspect that Facebook junkies rank up there with couch potatoes in terms of unused neurons. But a surprising new study looking at the brain sizes of Facebook users suggests just the opposite: people with the biggest online social lives also have bigger brains, according to

Specifically, the study found a strong correlation between the number of Facebook friends a person has and the amount of grey matter that exists in four key regions of the brain: the amygdala, right superior temporal sulcus, left middle temporal gyrus and right entorhinal cortex.

The study could only establish a correlative relationship, so it's impossible to say if having more Facebook friends is a cause or effect of bigger brains. Even so, the mere possibility that growing your Facebook profile could improve your cognitive capacity gives social media addicts everywhere fuel for the fire.

One might even imagine a future Facebook slogan: "Add a friend, grow your brain."

"Our study will help us begin to understand how our interactions with the world are mediated through social networks. This should allow us to start asking intelligent questions about the relationship between the internet and the brain," said professor Geraint Rees, one of the study's researchers.

Each of the enlarged regions of the brain noted in the study give hints about that relationship. The amygdala is a brain region known to be associated with processing memory and emotional responses, and the entorhinal cortex has been linked to memory and navigation.

Meanwhile, the superior temporal sulcus and the middle temporal gyrus have both been associated with the perception of where others are gazing, with the latter also being linked to the recognition of known faces — a skill certainly helpful in sifting through a large list of friend requests, for instance.

The study also looked at whether there was a link between the size of a person's online network of friends and the number of real-life friends they had. Researchers asked the 125 study participants questions about the kinds of text messages they receive, the number of friends in their contact lists, and how close they remain to old friends.

"Our findings support the idea that most Facebook users use the site to support their existing social relationships, maintaining or reinforcing these friendships, rather than just creating networks of entirely new, virtual friends," Rees said.

Dr. John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, which funded the study, summed up the significance of the results: "We cannot escape the ubiquity of the Internet and its impact on our lives, yet we understand little of its impact on the brain, which we know is plastic and can change over time. This new study illustrates how well-designed investigations can help us begin to understand whether or not our brains are evolving as they adapt to the challenges posed by social media."

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Can adding friends on Facebook grow your brain?
New study shows a strong correlation between the number of friends a person has on Facebook and the size of certain parts of their brain.