In 1996, Giacomo Rizzolatti and his colleagues at the University of Parma in Italy published a finding that many neuroscientists regard as a landmark. By means of electrodes inserted into the inferior frontal cortex of macaque monkeys, they discovered neurons that responded not only to the monkeys' own actions but also to similar actions the subjects observed in other monkeys. There is strong suggestive evidence of similar 'mirror neurons' in humans. Such neurons, now thought to have a role in understanding others' behaviour and emotions, have stimulated a great deal of fundamental research, as well as hypotheses relating to several cognitive disorders, including autism.

No grants committee could have foreseen the relevance of these fundamental primate experiments to human pathologies. That is precisely why a new directive proposed by the European Commission earlier this month requires action by anyone who thinks such research to be desirable.

The directive's intent, laudable in principle, is to introduce a new baseline of regulation of the use of animals in research across the 27 member countries of the European Union (EU). Standards of care currently vary greatly across the member states. So the draft directive would enforce on every lab a level of regulation already implemented in the countries most protective of research animals' interests. Such a reform is certainly needed. And indeed, although there is as yet no schedule for discussion and possible amendment by the European Parliament, it seems likely that a directive in some form will sooner or later be agreed by the parliament and the EU Council of Ministers.

For now, however, the urgent question facing the research community concerns the exact form that the directive will eventually take. As currently worded, it poses an immediate and substantial threat to neuroscience research and to the very benefits to human and animal health that the document says it wishes to support. In particular, it imposes major new restrictions on invasive research using primates. For any primate-research proposal to be approved, it would have to be shown that no alternative species might serve, and that there is relevance to serious diseases or conditions, or to species preservation.

Applied research is mostly carried out in species such as rats or mice for nearly all diseases, including neurological or psychiatric disease. Primates are instead important for more basic research — finding out how the brain works. Most of the labs carrying out invasive research on monkeys in Europe, by recording directly from single neurons, for example, study neurobiological aspects of consciousness such as attention, or decision-making, or how signals are coded in the brain.

Primates such as macaque monkeys are essential for such work given the similarity of their brains to our own. If we don't understand how brains function in health we will not come close to finding out how to fix brains in disease. It is hard to imagine how brain prosthetics and brain–machine interfaces, which are tantalizingly close to realization, could be properly developed without the support of fundamental primate studies.

The current wording of the directive's text could allow a broad permissive interpretation if an ethics committee decided that very basic research was indeed a prerequisite to finding cures to disease. But in the prevailing climate that seems all too unlikely. It is essential, therefore, that any directive clearly and explicitly permits fundamental research on non-human primates other than great apes. It is also essential that Europe's researchers contact their European Parliament members (MEPs) to tell them as much. They can be found here: MEPs will certainly be hearing from opponents to such research. In politics, the number of voices raised does matter.