Lady Greenfield reignited the debate over modern technology and its impact on the brain today by claiming the issue could pose the greatest threat to humanity after climate change.

The Oxford University researcher called on the government and private companies to join forces and thoroughly investigate the effects that computer games, the internet and social networking sites such as Twitter may have on the brain.

Lady Greenfield has coined the term "mind change" to describe differences that arise in the brain as a result of spending long periods of time on a computer. Many scientists believe it is too early to know whether these changes are a cause for concern.

"We need to recognise this is an issue rather than sweeping it under the carpet," Greenfield said. "We should acknowledge that it is bringing an unprecedented change in our lives and we have to work out whether it is for good or bad."

Everything we do causes changes in the brain and the things we do a lot are most likely to cause long term changes. What is unclear is how modern technology influences the brain and the consequences this has.

"For me, this is almost as important as climate change," said Greenfield. "Whilst of course it doesn't threaten the existence of the planet like climate change, I think the quality of our existence is threatened and the kind of people we might be in the future."

Lady Greenfield was talking at the British Science Festival in Birmingham before a speech at the Tory party conference next month. She said possible benefits of modern technology included higher IQ and faster processing of information, but using internet search engines to find facts may affect people's ability to learn. Computer games in which characters get multiple lives might even foster recklessness, she said.

"We have got to be very careful about what price we are paying, that the things that are being lost don't outweigh the things gained," Greenfield said. "Every single parent I have spoken to so far is concerned. I have yet to find a parent who says 'I am really pleased that my kid is spending so much time in front of the computer'."

Sarah-Jayne Blakemore, a cognitive neuroscientist at University College London and co-author of the book The Learning Brain, agreed that more research was needed to know whether technology was causing significant changes in the brain. "We know nothing at all about how the developing brain is being influenced by video games or social networking and so on.

"We can only really know how seriously to take this issue once the research starts to produce data. So far, most of the research on how video games affect the brain has been done with adult participants and, perhaps surprisingly, has mostly shown positive effects of gaming on many cognitive abilities," she said.

Maryanne Wolf, a cognitive neuroscientist at Tufts University in Massachusetts and author of Proust and the Squid, said that brain circuits honed by reading books and thinking about their content could be lost as people spend more time on computers.

"It takes time to think deeply about information and we are becoming accustomed to moving on to the next distraction. I worry that the circuits that give us deep reading abilities will atrophy in adults and not be properly formed in the young," she said.