Understanding the mechanisms of injury when someone is subject to a blast is a complex task. Dr Mitsuo Ohnishi, from the Department of Traumatology and Acute Critical Medicine at Osaka University Graduate School of Medicine, has long held an interest in this area. "My original interest was in the mechanism of primary blast injury, especially the effect of the blast wave to the thorax," says Ohnishi. He goes on to explain that this type of injury is unique. "Primary blast injury to the thorax produces bradycardia, hypotension and apnoea followed by rapid shallow breathing and this phenomenon is not seen when the shock wave is projected to the abdomen." This distinction proved to be important because the bradycardia, which is an abnormal slowing of the heart, and respiratory changes are under the control of the vagal nerve and the hypotension, low blood pressure, is partially a vagal reflex. This demonstrates that the blast wave is affecting the brain. "From here, colleagues demonstrated, via imaging techniques such as positron emission tomography (PET), that inflammation is occurring in the brain long after the initial injury and in regions not directly associated with the blast," continues Ohnishi. A picture is now emerging of how even mild brain injuries from blast shockwaves can cause neural changes and damage long after the wave subsides. Imaging technology has advanced this research recently and the discovery of the long-lasting inflammation was a major finding. Speaking of the aforementioned study Ohnishi says the findings "beautifully described the long-term effects of brain injury", further relating that this work is "the main background of our research". Not only did this work show that inflammation was occurring long after and away from the direct site of injury, but in doing so it confirmed that PET was a useful tool in tracking these processes. "This is an important step because now knowing that this is a progressive disorder, tracking the initiation, evolution, resolution and subsequent impact that inflammation has on neural networks will be crucial," he confirms. Having the ability to see where and how severe inflammation is also allows the team to evaluate treatment success as well. Ohnishi and colleagues believe that several treatment options may be available too. Pharmaceutical interventions may provide a healing or protective option while nutrition and exercise may be another way to reduce the effects of neuronal inflammation. However, in order to get this data, they require a large data set of brains whose injuries can be precisely categorised and the resulting symptoms, physical or otherwise, monitored and treated. Unfortunately, the only way to acquire such a data set is through the use of an animal model, which to date has not been available.