Susan Greenfield: The girl with all the brains

What sort of a teenager cuts open a rabbit's head for fun? The Susan Greenfield sort. Clever, solitary and bored, she once bought a dead animal from the butcher and carried it home, for an operation on the kitchen table. "I wanted to see the brain," she says. "I'd never seen one before." I imagine the scene in the bleached-out colours of a horror film. A girl. A knife. An open skull. A little boy mouthing something strange: "Alpha. Beta. Gamma. Delta ..."

Young Susan experimented on her brother, too. "I bullied him," she admits. "I made him learn the Greek alphabet. And Shakespeare – he could say, 'Out, out, brief candle!'" She was 16 at the time. How old was he? "Hmm? Yeah. He was three." Three years old and reciting Macbeth? "He had no idea what he was saying. He just did what I told him. I thought it was funny."

She still does, by the look of her face. And yet this is a woman who wants to warn us about what is happening to our young people today. The cold-hearted, knife-wielding teenager has grown into a brilliant neuroscientist with new theories about how computers, games and virtual lives are physically changing our brains – altering the way we think, make connections and function.

"The new technologies are invasive and pervasive as never before," she says, "and certainly in a way that the printing press, or the electric light, or the television were not."

We need – among other things – "a major overhaul of education" to prevent a generation of children becoming emotionally stunted, inarticulate adult hedonists with tiny attention spans, who can't differentiate between blasting away aliens on screen and happy-slapping grannies.

What would she know about anything? An awful lot, actually. Susan Greenfield is often described as the foremost female scientist in Britain, but she is one of the best of any gender, anywhere, at getting complicated ideas across. She is a successful broadcaster, for which it helps to be far more glamorous than your average Einstein-alike with sticky-up hair and lunch on his tie (today she is in black knee-length boots with stack heels, a black dress and a cerise crop-top cardigan). But image alone does not make you a writer of bestselling science books, a working peer, a professor of pharmacology at Oxford and a recipient of the Légion d'Honneur.

Baroness Greenfield, 57, is also director of the Royal Institution in London, founded in 1799 to "diffuse science for the common purposes of life". Michael Faraday and others gave landmark lectures at the RI, and 14 Nobel Prize-winners have worked in its laboratories. She has led a £22m makeover of the pillared building, which the Queen will reopen later this month. Besides the labs and lecture hall, there will be a glass atrium, a restaurant and a café, as Greenfield tries to turn the RI into somewhere people go to discuss quantum physics over a latte.

For now, though, the doors are closed. The dust sheets are down. The workmen are banging away. "Right," she says, safe in her office, wriggling like a hyperactive toddler tied to the chair. "The first thing to grasp is that the human brain is very sensitive to change. Which is why we occupy more ecological niches than any other species on the planet, yeah? We're not particularly strong, we don't see particularly well, we don't run particularly fast, but what we do brilliantly is adapt. Unlike a goldfish."

A goldfish? "Yeah." OK. "My second point is that the new technologies are so invasive because interacting with the screen, and doing so in a solitary way, mandates you living in two dimensions."

Which means what? "All the things I said in the new book." Ah yes. ID: The Quest for Identity in the 21st Century says people who spend a lot of time interacting through the screen can become emotionally detached, seeing life as a series of logical tasks that demand immediate reaction. Language gets crunched, along with the ability to imagine or analyse. Attention spans shorten. "Human beings always listened to stories and had long working memories. Now it's action, reaction, action, reaction."

What worries her most is a shift of focus from content to process. Think of a book about a princess locked in a tower, she says. You go on reading because you care about what happens to the princess. You're lost in the content of the story. Now think of a computer game about the same thing. "You don't give a stuff about the princess, do you? She's there as a goal." It's not about her. It's about you completing a task. "You focus on the process. The experience offered by a computer is the excitement of an anticipated reward. And frustration if you don't get it. In neurochemical terms, it's very similar to when you take a drug."

This is her specialist area. Rescuing the princess produces a chemical in the brain called dopamine, she says, which makes you feel good. But too much of it may damage the prefrontal cortex, and that can limit your ability to understand anything much beyond the here and now. Other addictions have the same effect.

"Many people like downhill skiing, or dancing, or wine, or sex, or food," says Greenfield. "Up until now, [pleasure seeking] has always been part of our lives but a polar opposite to seeking meaning. I fear we are shifting too much in favour of the literal, the hedonistic, the here and now, and losing meaning, context and content in favour of process."

What can an excess of dopamine (to put her thesis crudely) do to individuals? "It can mean a confusion of reality and screen life. The sort of people who, when they bash up old ladies in the street, record it on their mobiles to put on YouTube. That's monstrous." But they're not monsters, she insists. "It's like seeing an old Popeye cartoon where someone is steam-rollered and then gets up again." They half expect the old ladies to jump up again? "Uh-huh. These people can't take on board the consequences of their actions."

Great. Take back the Wii. But if you see the signs in your son or daughter (or yourself) what do you do? "You could help them by reading together, for example, and putting ideas into a contextual framework. You'd ask my brother, for example, whether 'brief candle' means literally a candle, or stands for something else."

She links the habit of seeking short-term reward, as learned on screen, with obesity, gambling addiction and the threefold rise in Ritalin prescriptions over the past 10 years. "An obese person, or a compulsive gambler, knows absolutely the consequences of what they are doing. But it's over-ridden by the thrill of the moment."

She also explains antisocial behaviour this way. "If you're trapped on a sink estate and you don't even know the capital of France because you've been excluded from school, you're stuck in a literal world where all your stimulation comes from your sensations," she says. "So is it surprising that you will eat strong, greasy, salty food to stimulate the tastebuds? Or kick down doors, or take drugs? The only way you can drive your brain is by grabbing strong sensations."

Greenfield is no Luddite, enthusing about the possibilities offered by nanotechnology and stressing that computer life offers "wonderful opportunities for collective creativity". She thinks schools should develop software and systems that help pupils see their screen lives in a much wider context. She has a plan, of course, should Gordon Brown ask. "Neuroscientists, computer experts and educationalists should work closely together, bankrolled by the Government."

Greenfield was a reader as a child. So much so that her mother asked the doctor's advice, thinking something must be wrong. Born in Hammersmith in 1950, she graduated from the rabbit brain to a human one at Oxford University. Her book describes what it was like. "I roll up my starched sleeve and plunge my hand into the reeking contents [of a tub of formalin], my groping fingers making contact with an object. And now I am holding in one hand what was once the essence of a human being."

How does that soft lump of grey matter translate into thoughts and feelings? She still burns to find out. "We don't even know what kind of answer would satisfy us."

Some of her critical peers whisper (always anonymously) that she can't be all that serious about science if she does so much. They infuriate her. "It's unfair. I publish three or four papers a year in peer-reviewed journals," she says. She fits it all in by "not doing what other people do: gardening, watching television, sleeping in late. I wake up between four and five. If it's a London day, I get the 6.30 train from central Oxford, where I live. I'll have a working breakfast here with my second in command, then a day of meetings or interviews. In the evening, I may chair an event or go to a reception."

On Oxford days she wears T-shirt and jeans, but is still in the lab by 7.30am, planning experiments, applying for grants, analysing and writing papers. She plays squash three times a week. With a trainer. "He pushes me to improve my skills." At weekends? "I write, read, prepare talks."

Her marriage to Oxford professor of physical chemistry Peter Atkins ended in 2005. Is all this activity a way to escape loneliness? "You can be lonely when you're with someone," she says quickly, "as much as when you're by yourself."

Lady Greenfield won't be short of company when she's director of the smartest (in every sense) venue in London. "Some people still hope one is going to mess up. When I first came to the RI 10 years ago, Nature magazine ran an editorial showing me in a miniskirt, under the headline: 'Highbrow club gains the common touch.' I was proud, actually. My father was an electrician, mum was a dancer. I am proud one can democratise science and bring in a sense of irreverence and fun."

Work and fun go together like hydrogen and oxygen (or gin and tonic) in the busy world of Lady Greenfield. "There's no point of living life if it's not fun," she says. "OK? Great. Thanks." She rises, free of that chair at last. "Let's see, what am I doing next?"

Life story

Born in Hammersmith, 1950 Daughter of a dancer and an electrician.

Educated at Godolphin and Latymer School.

First-class degree followed by D Phil at Oxford. Now professor of pharmacology there, researching Alzheimer's.

Founding director of research companies Synaptica and BrainBoost.

Became director of the Royal Institution in 1998. Awarded Michael Faraday Medal the same year.

Fellow of the Royal College of Physicians. Made a life peer in 2001. Awarded the Légion d'Honneur in 2003. Honorary Australian of the Year, 2006.