As luck would have it, on the morning of my interview with a Bolte Taylor, I have a hefty row with someone, so that in the taxi en route to our appointment I'm deafened by what the neuroanatomist would call "left-hemisphere brain chatter" - namely "cognitive loops" that replay stressful exchanges and destroy one's equanimity. Bolte Taylor's book, My Stroke of Insight, contends that, with a little mental effort, we can break these circuits and be less annoyed with each other. After being taken up by Oprah, it has become a bestseller. It has also provoked more than one person to whom I mention it to say, "She has obviously never met my mother."

"Mood management" - the idea that you have a greater control over your responses than you think - is a thriving subset of the self-help market, combining motivational training and bits of spiritualism with the legitimising language of neuroscience. The singular thing about Bolte Taylor's book is that it is based on her experience of having a stroke. At the age of 37, she woke one morning feeling odd and within 20 minutes was unable to speak, walk or discern the boundaries of her own body. While a large part of her was alarmed, another part analysed her own deterioration from a clinical point of view, and as blood pooled in her left hemisphere, thought, "Wow, this is so cool!"

That was almost 12 years ago. What happened in the months immediately afterwards convinced her that she had been living her life at a fraction of its possibilities; that she was actually happier when relying on the right side of her brain. The stroke was caused by a severe haemorrhage in her left hemisphere, that which, she says, is responsible for language, ego, ambition, self-criticism - "money, prestige, being better than you in the hierarchy ... drive, drive, drive, drive, drive" - all the things that, as a Harvard-trained neuroanatomist, she had valued to the exclusion of what she calls right-hemisphere attributes: "where everything is connected, everything is in flow, you're looking at the big picture. The left hemisphere provides the details of the external world. The left hemisphere thinks in language, the right in pictures. Two very different worlds."

With her left hemisphere effectively "off-line", Bolte Taylor had the experience of being able to feel what she had hitherto only studied on the page and in dissection; the difference between the two halves of a brain. She lay in the hospital bed with almost no conceptual sense of the world - she would look at a telephone and have no idea what it was for. She didn't know who anyone was, including her mother - or indeed what a "mother" was. Language came to her in fits and starts; she would talk gibberish, but imagine it was coming out perfectly. And although she could read people's facial expressions, she could not understand what they were saying.

Instead of feeling panicked, what she felt was peaceful and "at one with the universe". She writes, "I believe the experience of nirvana exists in the consciousness of our right hemisphere." (She defines nirvana as "the absence of experience".) After a successful operation to drain the blood, she moved from Boston back to her parents' town in Indiana and set about remaking her life.

Words such as "nirvana" do not sit well in scientific circles and there has been some left-brain chatter about the propriety of Bolte Taylor's thesis; the way she frames her experience purely in terms of general right-brain/left-brain activity, rather than, say, the very specific activity of the right brain during a stroke. Might not the right hemisphere function differently when the left is undergoing massive trauma? And how do we begin to understand the relationship between brain biochemistry and the metaphorical language used to describe its effects? (Bolte Taylor is sensitive to this: "I could call nirvana 'God', and that's going to turn certain people off.")

Earlier this year, she gave an 18-minute speech at a conference in California, describing her stroke and manhandling a human brain on stage. The audience was moved and enthralled, and footage of her performance found its way on to YouTube, where it became an instant hit and inevitably got back to Oprah. Since then, the questions most people have wanted to ask of her are: has the remarkable nature of her recovery - she learned to speak, read, walk and understand the world again in eight years, and now holds a teaching post at the Indiana University School of Medicine - anything to do with her understanding of the brain? And the nirvana thing: can we all get a piece of that?

Bolte Taylor, who is in New York for a few days for more rounds of publicity, says that yes, she believes that being a neuroanatomist did give her an advantage during recovery; just by knowing that her brain cells had a certain "plasticity", she was able to encourage them to heal. "I think visualisation is the key to healing," she says - in other words, she recovered, in part, because she believed she could recover. And yes, she says, there are general lessons about happiness to be learned from this: primarily (and this accounts for the success of her book), how to switch off stress.

A lot of what she says is a perfectly sensible take on how to limit one's neuroses, but occasionally Bolte Taylor drifts into Noel Edmonds-style cosmic-ordering territory. "You look at a body and think, 'Oh my God, I've got breast cancer'; and you think, 'OK, well I've got breast cancer cells, and 50 trillion other healthy ones.' And so, are you going to encourage the cancer cells, and help them and encourage them, consciously or unconsciously? Or are you going to consciously feed the intention of the other cells to wipe them out?" (There is no scientific consensus to support the notion that if you have cancer, "visualisation" or "positive thinking" increase your chances of survival; in fact, some of the "killer cells" supposedly activated by positive thinking were shown in an article in Scientific American last year to be traitor cells that actively encouraged the tumour.)

The broader point Bolte Taylor makes about stress and relationships is that, in the 90-second aftermath of a row, we are all at the mercy of our biochemical reaction - "anger" as we call it - but that after it subsides we have a choice: to hang on to it or to let it go. It is, she says, a question of recognising that "emotions and relationships are just circuitry" and can therefore be resisted or rewired. Even if the person you've been arguing with is really, really annoying? With a flourish, Bolte Taylor cites her own mother, who before she had the stroke could wind her up like nobody else. But after the stroke, she says, it was like pushing "the reset button". "And so it was fascinating for both of us, because she had no power. Her power was gone. I looked at her differently; I did not respond to those things that I had been trained throughout my life to respond to."

Her mother must have loved that.

"Yeah, I don't think she liked it at all. We had to establish a new relationship. And she would try this stuff on me and I would say to her, 'That's not effective any more. That's not the relationship we have any more.' And she got it, real quick. And we became equals in this process and it was beautiful because we got to bury all the garbage."

Realistically, hitting the reset button sounds like something most ordinary people might only achieve by getting comprehensively stoned, shutting themselves in an isolation tank or actually having a stroke; but Bolte Taylor insists it is just a question of recognising and then bypassing the circuitry. "I try to think of something that is funny. I just go somewhere else. You have the choice of changing the focus of your attention. Some of us get into fights and we go around thinking, I should've said this, they did that to me, and that's your left hemisphere, just egging it on, egging it on. And then let's say the phone rings, you get really excited about something else and then you hang up the phone. And then you have a choice."

When she talks about celebrating the fact that "we're on the planet together and how sweet that is", it sounds less like an insight into brain control and more like the upshot of a near-death experience. "I haven't really thought about that, from that perspective. I guess maybe I should. Because I did [nearly die]. I said goodbye. I let go. And when I let go I just felt this incredible peace. And then to wake up and find out I wasn't dead was not a positive thing, necessarily. It was painful, because the euphoria was in the absence of my form, and the form wasn't working, and I felt like a tonne of lead in bed."

She talks about her life pre-stroke in strange terms. "That woman is dead," she says. "That woman died that morning. She's gone and so have her likes and dislikes. She's gone and we have this new Jill."

The new Jill is happier. She's less angry and less judgmental. She likes squash. (She used not to like squash.) A different kind of man asks her out. "I'm not climbing the Harvard ladder, I'm not in the left-hemisphere consciousness, so someone who is attracted by that is not going to be attracted to me." And the irony is that she is more successful. She urges us to be more like her, then; to get off the ladder, be nicer to each other and, when we die, to leave our brains, for further study, to Harvard.

· My Stroke of Insight: A Brain Scientist's Personal Journey by Jill Bolte Taylor is published by Hodder & Stoughton, priced £12.99. Watch Bolte Talor's speech How it Feels to Have a Stroke on: www.youtube.com/watch?v=UyyjU8fzEYU