FUNCTIONAL IMAGING FINDINGS OF WORKING MEMORY AFTER TRAUMATIC BRAIN INJURY: A META-ANALYSIS

Open Access
Author:
Rostami, Sohayla
Area of Honors:
Elective Area of Honors - Neurosciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Frank Gerard Hillary, Thesis Supervisor
  • William Ray, Honors Advisor
Keywords:
  • Traumatic Brain Injury
  • TBI
  • functional Magnetic Resonance Imaging
  • fMRI
  • Adult
  • Pediatric
  • Working Memory
  • WM
  • Memory
  • Moderate
Abstract:
In the past decade, a number of studies have examined cognitive function in individuals with traumatic brain injury (TBI) via functional neuroimaging techniques. Independent research has demonstrated increased functional activation in TBI samples during cognitive tasks, especially assessments involving memory retrieval. The following meta-analysis compiles findings within neuropsychology literature on individuals with TBI compared to demographically matched healthy controls (HC) to examine executive functionality via memory tasks measured through functional magnetic resonance imaging (fMRI). This work analyzes neural recruitment in individuals who have sustained moderate to severe brain injury; thus, giving a greater insight into the brain’s recovery mechanisms and neuroplasticity after injury. It is hypothesized that adults and pediatrics with TBI reveal greater memory impairments associated with increased cerebral activation in the right hemisphere, irrespective of the memory task or TBI severity. Prefrontal cortex (PFC) recruitment in adult TBI subjects will be most commonly observed while widespread hyperactivation is predicted in pediatric TBI. The scientific databases of the National Institutes of Health, PubMed, were used to obtain 23 primary research articles based on specific search terms and criteria. Functional neuroimaging data from the studies were compiled for the TBI study group and healthy controls. Results were tabulated in the GingerALE software were used to compare the cerebral activation between both groups and viewed in MRICron imaging software. The adult TBI study group predominantly revealed greater activation in the right cerebral hemisphere with other loci of activation scattered throughout the brain while the adult HC mainly revealed symmetric activation across the brain. In pediatric study groups, activation was distributed throughout the cerebrum with approximately the same intensity of activation at each foci. Generally, both hemispheres were recruited during task completion as illustrated. Greater cerebral activation in adult TBI suggests a shift of neural recruitment to the frontal lobes of the brain to compensate for lost functionality in other injured regions of the cerebral network. On the other hand, the wide distribution of neural activity on both hemispheres in pediatric TBI suggests that the brain regions where function was lost or hindered through injury attempts to recovery and retrieve previous functionality. Understanding these properties and trends would allow for a better approach to treat patients with TBI.