Abstract : Mild traumatic brain injury may affect as many as 400,000 soldiers returning from recent wars in Afghanistan and Iraq. To determine how shockwaves directly affect neurons, we used a biolostic gene gun to deliver shockwaves to cultured hippocampal or cortical neurons. These cultured cells form abundant synapses in vitro, and after a 24-48 hour period of incubation following shockwave exposure, immunocytochemical labeling showed a significant reduction in synaptic densities in shockwave-exposed cultures compared to control cultures. While the molecular mechanism responsible for this phenomenon is not known, these results suggest that shockwaves emanating from explosive devices may specifically affect synaptic plasticity in the brain.