Journal:Archives of Neurology
Year, Volume, Issue, Page(s):11, 68, 1, 74-84
Study examined the functional connectivity of hippocampal and selected frontal lobe circuits in patients with traumatic axonal injury (TAI). Twenty-five patients with brain injuries consistent with TAI and acute subcortical white matter abnormalities were studied as well as 16 healthy volunteers of similar age and sex. Echo-planar and high-resolution magnetic resonance images were acquired. Regions of interest (ROI) were drawn bilaterally for the hippocampus, anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex and were used to extract time series data. Blood oxygenation level-dependent data from each ROI were used as reference functions for correlating with all other brain voxels. Interhemispheric functional connectivity was assessed for each participant by correlating homologous regions using a Pearson correlation coefficient. Patient functional and neurocognitive outcomes were assessed approximately 6 months after injury. Patients showed significantly lower interhemispheric functional connectivity for the hippocampus and ACC. Controls demonstrated stronger and more focused functional connectivity for the hippocampi and ACC, and a more focused recruitment of the default mode network for the dorsolateral prefrontal cortex ROI. The interhemispheric functional connectivity for the hippocampus was correlated with delayed recall of verbal information. Findings suggest that TAI may affect interhemispheric neural activity, as patients show disrupted interhemispheric functional connectivity.