Researchers from Vanderbilt University Medical Center are beginning a new five-year study to characterize the role of a memory system in behavioral deficits commonly seen in individuals with traumatic brain injury (TBI).
The study, backed by more than $3 million in funding and conducted in collaboration with the University of Illinois, will analyze the impact of relational memory impairments on flexible and goal-directed behavior to improve interventions and outcomes for individuals with TBI.
According to Melissa Duff, PhD, the study’s lead investigator, many researchers attribute behavioral deficits in TBI almost exclusively to damage to the individual’s frontal lobes, but interventions designed to target this area of the brain have not shown significant improvements in behavior or functional outcomes.
This study proposes that the ability to adapt one’s behavior greatly depends on the function of the hippocampus, which plays a major role in memory and learning, and that interventions for TBI may also need to target this region to be effective.
“Although we know TBI is a diffuse condition, we have come to see it as primarily a frontal lobe condition. But, the hippocampal relational memory system, when damaged in isolation, produces many of the deficits that people with TBI have but that are never linked back to this neural system,” said Duff, associate professor of Hearing and Speech Sciences at VUMC.
“Our proposal is that the exclusive focus on the frontal lobes may be too limiting to improve the impairments in flexible and goal-directed behavior that are a hallmark of TBI. Our focus on hippocampal relational memory represents a novel direction in TBI research, but we hope it also informs interventions for other populations where disruption in hippocampal function are also common, such as in Alzheimer’s disease and schizophrenia.”
Leaving significant deficits in relational memory untreated could also prevent the success of interventions that target the frontal lobes, researchers argue, as all successful behavioral interventions rely on the capacity for memory and learning. Placing more focus on the hippocampus could expand existing interventions to include things like exercise and nutritional approaches, which have both been shown to impact the hippocampus.
The study will examine 100 participants with TBI through computer-based assessments that test different aspects of relational memory — as well as their general cognitive ability in areas such as speech, language, attention and motor skills — to get a global assessment of their functioning. Participants will also receive neuroimaging scans of their whole brain and of the hippocampus.
Researchers hope the study will provide greater insight into how the hippocampus contributes to impairments in TBI and how it works in concert with the frontal lobes in healthy people. They will also look at how disruptions in the connectivity between the two structures could lead to behavioral impairments.
“Dr. Duff’s contributions to our understanding of brain injury continue to be outstanding. This expansion of her work in the role of the hippocampus and relational memory will alter our ability to provide effective interventions to patients with TBI and, potentially, to other patients with hippocampal dysfunction,” said Anne Marie Tharpe, PhD, chair of the Department of Hearing and Speech Sciences and associate director of the Vanderbilt Bill Wilkerson Center.
This research is supported by the National Institute of Neurological Disorders and Stroke (grant NS110661).
