Warning: this episode contains descriptions of violence and self harm. Last fall, an Army reservist killed 18 people at a bowling alley and restaurant in Lewiston, Maine, before turning the gun on himself. Dave Philipps, who covers military affairs for The Times, had already been investigating the idea that soldiers could be injured just by firing their own weapons. Analyzing the case of the gunman in Lewiston, Dave explains, could change our understanding of the effects of modern warfare on the human brain. Guest: Dave Philipps, who covers war, the military and veterans for The New York Times.