The brain is the most complex organ in the human body, yielding an incredible ability to calculate, reason and communicate that is beyond the rest of the natural world. This complexity has allowed us to become successful as a species; however, this same complexity makes understanding what happens when the brain goes awry equally complex and difficult to decipher. The sophisticated interconnection and construction of the brain also takes a long time to complete, lasting across prenatal development through all the way into adulthood. The greatest changes take place in the later stages of pregnancy and in the first few years of life. Consequently, this is also the time when the young brain is most vulnerable to environmental stressors. Anything that is capable of disrupting the delicate developmental process can have drastic effects later in life. Measuring, understanding and predicting disruption in the developing brain is of paramount importance if solutions and preventative measures are to be implemented. In particular, it is important to quantify the impact of common stressors such as alcohol and methyl mercury as these are the most likely to come into contact with the developing brain. While it has long been known that these chemicals are correlated with an adverse effect on development and in later life, their mechanism of their action has not been fully elucidated. This makes it tricky to propose treatments beyond avoidance, something that is not always possible. What is possible, however, is that there is a common mechanism underlying these stressors. Whilst the stressors themselves can have drastic effects on individual cells, their broad impact in development is likely to stem from some organ-wide response to their presence. If this were the case, it would also be likely that common treatment or preventative could be found for nearly all environmental stressors. Dr Seiji Ishii has recently set up his own group at Keio University to investigate the cause of environmental stress damage. This has arisen from successful post-doctoral studies at the Children's Research Institute in Washington D.C., USA.