Scientific research requires many skills and no one has them all. It needs dreamers, pedants and leaders. It needs an environment where everything is open to questioning, and this can only happen when people don't all come from the same place and point of view. Just as science needs more people from diverse cultural backgrounds, it needs more women.

There are reasons for optimism: more girls are taking A-levels in the sciences and more of them are carrying on to do undergraduate and higher degrees in scientific fields. Yet, as young female scientists reach their mid-twenties, the numbers begin to drop. It's a vicious circle - without mentors in the subject, young people are far less likely to sign up.

In 2002, I led a team writing a report on women in science for the government, which exposed the difficulties in attracting more women into the field and then keeping them there. Sadly, the situation remains unchanged and it won't improve until there is proper investment. The new government has yet to tackle fully the question of provision for scientific research. It's a worrying silence. And the lack of funding raises many challenges that affect women in particular.

Having children hugely limits a woman's progress in any profession. A female scientist in her mid-twenties who wants a family is faced with a difficult choice. She can delay getting pregnant, which will mean waiting until she is beyond her biological optimum. In science, you might, if you are lucky, get tenure in your mid-thirties. On the other hand, those who take time out to have children in their twenties miss the crucial postdoctoral phase of their career when a scientist is first knowledgeable enough to have her own ideas and be proficient in the lab. When women who have children in their twenties return to their career, they find their male peers have published extensively. A new parent will only struggle in such a competitive field.

In 2002, I proposed making ring-fenced fellowships available to scientists who are also their children's primary carer. It wouldn't be sexist - the awards would be open to men, too. Then, the government put a pathetically small sum of money into the scheme. I would like to see similar fellowships available now. There are already schemes that work along these lines, such as the awards given out by the Daphne Jackson Trust and L'Oréal's Women in Science fellowships, which I am involved in. But even for the L'Oréal award - worth £15,000 each - there are about 200 applications for just four or five bursaries. Getting funding should not be as unlikely as winning the Lottery. But things will continue to be this way until the government puts in some serious money.

A few steps would help women in any profession. British institutions could learn from their French counterparts, some of which have crèches on site. Then there are more science-specific solutions. Job-sharing couldn't work for a research scientist, but employing technicians to complete some of the more routine work and collect data would make it possible for mothers to spend more time at home.

Unusual pressures

Above all, we need a change of culture. Think of it like the change in attitudes to fur coats. When I was growing up, ladies wore mink coats. These coats have never been the subject of legislation, but if you saw someone wearing one today, you would do a double-take. The media can play a part in portraying female scientists as good role models - using them as commentators, for example.

The mindset of male scientists also needs a bit of work. I often go to meetings and see a middle-aged senior scientist with an entourage of attractive young female graduates. On the one hand, you think: "Look at all the young women in science!" But the power lies with the male, senior scientist, like a magus with his handmaidens.

Women scientists face unusual pressures at every stage of their working life, even when they are quite senior. By then, they would be all too well aware that they are carrying the torch for women. Yet, it is at this time that they may meet particular antagonism. When someone capable and advanced in their career looks different from the norm, people feel insecure.

Over the years, women have been encouraged to make men look good and not to be too pushy. But scientific research is like a painting - it's your project, your baby. If two scientists are doing an experiment, they will have different interpretations of the results and they will see different priorities. Within a few weeks, they could be doing very different types of research, because, while the techniques are impartial, the planning and interpretation are very personal.

It's not that women need to become aggressive and arrogant; it would be very nice if men stopped being like that. But an upbeat attitude can be helpful, especially at a time of dire fin­ancial straits. There are little things scientists can do in their sector to make a difference.

For example, an initiative I'm launching, called Screening the Mind, will raise funds for research into how science and technology affect the way people think and learn, especially children. There are two aims. One is to encourage debate, but the other is to get funds for research. Ultimately, all the goodwill and cultural change is no substitute for hard cash.

Susan Greenfield is professor of pharmacology at Oxford University.