Your News story “Race is on to find alternative to animal tests” (Nature 418, 116; 200210.1038/418116a) discussed the possibility that in vitro methods could replace animal tests used in the toxicologic screening of chemicals. However, it is highly unlikely that in vitro approaches could be used to replace in vivo animal tests in the assessment of neurotoxicity. For instance, behavioural assessment in rodents is a powerful experimental tool in the evaluation of the effects of chemicals on neural function. Pharmaceutical companies and regulatory agencies consider behavioural toxicology an important part of the screening of new pharmaceutical products and potentially neurotoxic chemicals.
It is true that in vitro experimental approaches can be used in the investigation of the cellular and molecular mechanisms of behaviour. But drug-induced alterations in parameters such as anxiety, motor activity, and learning can only be assessed by in vivo tests on mammals. It is not possible to replace such tests with non-animal methods using, for example, human cells or yeast.