WVSJ Network: Radiology: fMRI showcases brain’s resilience after mild TBI

Wednesday, August 1, 2012

Radiology: fMRI showcases brain’s resilience after mild TBI

Written by Evan Godt

July 30, 2012

In patients who have sustained mild traumatic brain injury (MTBI), differences in working memory functional activity were observed with MRI even though patients performed as well as controls on working memory tests, according to a study published online July 24 inRadiology.

Study authors Chi-Jen Chen, MD, of Taipei Medical University/Shuang Ho Hospital in New Taipei City, Taiwan, and colleagues said the results indicated the inclusion of MR imaging evaluation may increase sensitivity to MTBI compared with neuropsychological evaluation alone.

“This study determined that, despite no apparent differences in neuropsychological tests, brain activation patterns differed between MTBI patients and control subjects in response to increasing working memory loads,” wrote the authors.

A total of 20 patients with MTBI and 18 healthy control subjects were included in the study. Subjects were given n-back continuous performance tests, and functional MRI was used to asssess brain activation patterns in response to the tests. In the MTBI group, imaging was conducted within one month after injury.

N-back working memory tasks are conducted by presenting subjects with a sequence of stimuli, and the subjects are tasked with indicating when the current stimulus matches one from a certain number of steps earlier in the sequence. In the current study, subjects were given one-back, two-back and three-back tests in which they monitored a series of numbers and indicated when the current number matched a previous number from one, two or three steps prior, respectively.

Chen et al reported that the study groups performed similarly well on the n-back working memory tasks. The groups were statistically similar for sex, years of education and performance on a digit span memory test in which subjects were asked to remember an entire sequence of numbers.

Brain activation patterns differed between subjects, with controls able to increase activation in working memory circuitry as the working memory load required for the tasks increased. “In contrast, MTBI patients were impaired in their ability to increase activation in working memory circuitry under both moderate and high working memory load conditions,” wrote the authors. “However, MTBI patients did show cerebral plasticity, as evidenced by more activation in some areas outside and inside the working memory circuitry as compared with control subjects.”