Since 2001, an estimated 150,000 members of the U.S. military have suffered mild TBI as a result of exposure to bomb blasts. Mild blast-induced TBI is hard to diagnose, yet it can cause a range of neurological and psychological problems. Scientists know little about how a bomb blast affects the brain in these cases, making these injuries difficult to study.
Researchers in the Section on Membrane and Cellular Biophysics, within the Division of Intramural Research Program in Physical Biology, have found a way to study the effect blasts have on brain cells cultured in the laboratory. Using a modified air gun, the scientists created varying amounts of pressure on cells under a microscope.
They discovered that the force of the blast did not affect the cells; rather, the change in the cells occurred when the force of the blast was combined with “shear force.” Shear force is created when the pressure wave of the blast travels through different tissues of the brain at different speeds. The brain cells can survive under these conditions, but the stress may alter the cells’ electrical activity and the function of the cells’ membranes.
The scientists also observed a brief elevation of calcium among the cells following a blast with shear force. This finding is important for future study, because prolonged elevated calcium levels may play a role in brain cell death (PMID: 22768078).