title: Deficits in functional connectivity of hippocampal and frontal lobe circuits after traumatic axonal injury.
abstract: OBJECTIVE
  To examine the functional connectivity of hippocampal and selected frontal lobe circuits in patients with traumatic axonal injury (TAI).
  
  
  METHODS
  Observational study.
  
  
  METHODS
  An inpatient traumatic brain injury unit. Imaging and neurocognitive assessments were conducted in an outpatient research facility.
  
  
  METHODS
  Twenty-five consecutive 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.
  
  
  METHODS
  Echo-planar and high-resolution T1-weighted images were acquired using 3-T scanners. 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.
  
  
  METHODS
  Interhemispheric functional connectivity, spatial patterns of functional connectivity, and associations of connectivity measures with functional and neurocognitive outcomes.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  Traumatic axonal injury may affect interhemispheric neural activity, as patients with TAI show disrupted interhemispheric functional connectivity. More careful investigation of interhemispheric connectivity is warranted, as it demonstrated a modest association with outcome in chronic TBI.
authors.affiliation: Center for Brain Health, University of Texas at Dallas, Richardson, USA.
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Marquez de la Plata
authors.forename: Juanita
authors.initials: J
authors.lastname: Garces
authors.forename: Ehsan
authors.initials: E
authors.lastname: Shokri Kojori
authors.forename: Jack
authors.initials: J
authors.lastname: Grinnan
authors.forename: Kamini
authors.initials: K
authors.lastname: Krishnan
authors.forename: Rajesh
authors.initials: R
authors.lastname: Pidikiti
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Spence
authors.forename: Michael D
authors.initials: MD
authors.lastname: Devous
authors.forename: Carol
authors.initials: C
authors.lastname: Moore
authors.forename: Rodderick
authors.initials: R
authors.lastname: McColl
authors.forename: Christopher
authors.initials: C
authors.lastname: Madden
authors.forename: Ramon
authors.initials: R
authors.lastname: Diaz-Arrastia
mesh_terms: D000293:Adolescent; D000328:Adult; D001930:Brain Injuries / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D020833:Diffuse Axonal Injury / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult