In honor of Veterans Day,Technology Review is again highlighting some recent advances in understanding traumatic brain injury--a central issue for many of the troops returning from Iraq and Afghanistan. We first highlighted this problem in a feature in 2007, Brain Trauma in Iraq.

This year, David Moore, a neurologist highlighted in the feature, showed that diffusion tensor imaging, a brain imaging technology, could distinguish between blast-related injuries and other sources of concussion.

According to a recent story of ours:

The blasts caused by improvised explosive devices in Iraq and Afghanistan appear to inflict a fundamentally different type of brain damage than do more traditional sources of concussions, such as blunt trauma. The findings point toward new approaches to diagnosing and monitoring these injuries, which have been a huge concern to the military in recent years. The research also begins to resolve a controversy in brain-injury research--whether soldiers who are near an explosion but don't get hit in the head can still suffer a unique type of brain damage.

Regular concussions are typically caused by direct impact to the head, such as in a fall, or acceleration injuries, as in car accidents. In contrast, blast-induced brain injuries can include both of these factors as well as one that is unique to explosions--a rapid pressure wave that may wreak its own havoc on the brain. As a growing number of troops return from Iraq and Afghanistan with signs of brain injury--post-deployment surveys suggest that 10 to 20 percent of all deployed troops have experienced concussions--the military has been under increasing pressure to understand how this pressure wave affects the brain, as well as how best to diagnose and treat the resulting injuries.

Typically, damage from concussions does not show up on traditional medical imaging tests, such as CT scans or MRIs. But scientists have recently begun using a variation of MRI known as diffusion tensor imaging (DTI) to detect damage to the brain's white matter--the neural wiring that connects cells--after mild traumatic brain injury.

In the new study, David Moore, a neurologist and deputy director for research at the Defense and Veterans Brain Injury Center in Washington, D.C., and colleagues used DTI to assess troops who had been diagnosed with mild traumatic brain injury following a blast, a direct impact, or an acceleration-induced injury several months prior, as well as healthy people who had never suffered a concussion. They found that those with blast-linked trauma had a more diffuse pattern of damage to the white matter, described as a "pepper-spray pattern," than those whose concussions were caused by direct impact or acceleration. The research was presented at the World Congress for Brain Mapping and Image Guided Therapy conference in Boston last month.

Researchers are also pushing forward a blood test to assess more severe brain injuries. According to the piece,

One blood test already used in Europe to screen head-trauma patients before CT scans detects a protein called S100B, which is released by astrocyte cells in the brain after injury. "The thinking is, if you don't have [this marker] in the blood, then you don't have the kind of brain injury you could see on CAT scan," says Jeffrey Bazarian, an emergency-room physician and scientist at the University of Rochester Medical Center, in New York. The test is not approved for use in the United States, however. In a set of clinical guidelines for evaluating head trauma published recently, Bazarian and others estimated that the S100B test could significantly reduce unnecessary CT scanning. "We predict it could eliminate unnecessary radiation in a lot of people--about 30 percent [of those who come into the ER with brain injury]," he says.

Tone-deaf people--those who can't hold a tune--appear to be missing a specific neural circuit, according to research published today in the Journal of Neuroscience.

Researchers used a variation of MRI called diffusion tensor imaging to compare neural circuits--specifically those between the right temporal and frontal lobes--in the brains of people who are tone-deaf and those who are not.

According to a press release from the Society for Neuroscience, which published the research,

This region, a neural "highway" called the arcuate fasciculus, is known to be involved in linking music and language perception with vocal production.The arcuate fasciculus was smaller in volume and had a lower fiber count in the tone-deaf individuals. More notably, the superior branch of the arcuate fasciculus in the right hemisphere could not be detected in the tone-deaf individuals. The researchers speculated that this could mean the branch is missing entirely, or is so abnormally deformed that it appears invisible to even the most advanced neuroimaging methods.