FORT CAMPBELL, Ky. — Every soldier who's gone to war in the past year paused before leaving to take a brain test — basic math, matching numbers and symbols and identifying patterns to measure response time and accuracy. Now that some of these troops have returned, they're taking a fresh round of tests, part of a broad effort by the military to better treat head injuries.

Funding for such treatment is expected to increase under President Obama, who said Thursday his new military and veterans' affairs budget will focus on diagnosing brain injuries and psychological disabilities that have gone untreated.

More than 150,000 service members in the Marines, Air Force, Army and Navy have undergone the pre-deployment testing that became mandatory last year. Those who suffer a concussion or similar head injury will get a follow-up test.

The 101st Airborne Division is the only division going a step further and testing all soldiers again over the past few months as they have been returning to Fort Campbell from tours in Iraq and Afghanistan.

The tests alone can't diagnose traumatic brain injuries — potentially crippling and sometimes hard-to-detect damage from the force of an exploding roadside bomb, a mortar blast or a vehicle crash.

But they help doctors zero in on which mental functions are damaged and the best way to treat that, by comparing a soldier's brain function before and after the injury.

Dr. David Twillie, director of a newly opened brain injury care center at Fort Campbell, says the individual results are necessary "because the brain is a fairly complex organ and because when they experience a fall or a blast, there's no way to necessarily pinpoint what particular structures within the brain were injured, because the injuries are microscopic in nature."

Military doctors estimate that 10 percent to 20 percent of soldiers sent to Iraq or Afghanistan suffer a traumatic brain injury.

Before a mortar round shook him up in Afghanistan, Sgt. 1st Class Landon Ranker, 38, could lead an entire platoon of infantry soldiers through complicated tasks. His injury made it hard for him focus in stressful and confusing situations.

Part of his therapy is practicing to focus in a battle simulation: a fake mess hall bombing with several training dummies that bleed and breathe and need medical attention.

"It definitely makes your brain work in overdrive," he said.

With each small success, such soldiers regain confidence in their ability to return to their jobs, Twillie said.