Is Traumatic Brain Injury Associated with Reduced Inter-Hemispheric Functional Connectivity? A Study of Large-Scale Resting State Networks following Traumatic Brain Injury

Abstract

Traumatic brain injury (TBI) often has long-term debilitating sequelae in cognitive and behavioral domains. Understanding how TBI impacts functional integrity of brain networks that underlie these domains is key to guiding future approaches to TBI rehabilitation. In the current study, we investigated the differences in inter-hemispheric functional connectivity (FC) of resting state networks (RSNs) between chronic mild-to-severe TBI patients and normal comparisons (NC), focusing on two externally oriented networks (i.e., the fronto-parietal network [FPN] and the executive control network [ECN]), one internally oriented network (i.e., the default mode network [DMN]), and one somato-motor network (SMN). Seed voxel correlation analysis revealed that TBI patients displayed significantly less FC between lateralized seeds and both homologous and non-homologous regions in the opposite hemisphere for externally oriented networks but not for DMN or SMN; conversely, TBI patients showed increased FC within regions of the DMN, especially precuneus and parahippocampal gyrus. Region of interest correlation analyses confirmed the presence of significantly higher interhemispheric FC in NC for the FPN ( p < 0.01), and ECN ( p < 0.05), but not for the DMN ( p > 0.05) or SMN ( p > 0.05). Further analysis revealed that performance on a neuropsychological test measuring organizational skills and visuo-spatial abilities administered to the TBI group, the Rey-Osterrieth Complex Figure Test, positively correlated with FC between the right FPN and homologous regions. Our findings suggest that distinct RSNs display specific patterns of aberrant FC following TBI; this represents a step forward in the search for biomarkers useful for early diagnosis and treatment of TBIrelated cognitive impairment.

The female advantage: sex as a possible protective factor against emotion recognition impairment following traumatic brain injury

“…Indeed, one limitation of the study lies in the fact that different types of severity information were available for participants with TBI. The Mayo classification system (Malec et al, 2007), which allows researchers to indicate TBI severity by combining all available pieces of information, has been extensively used in a wide variety of studies (Baxter et al, 2013; Ham et al, 2014; Rigon, Duff, McAuley, Kramer, & Voss, 2015) since its publication. However, because in the current study determined severity by different factors for each participant, within group comparisons and correlations between TBI severity and behavioral performance were not feasible.…”

Different aspects of facial affect recognition impairment following traumatic brain injury: The role of perceptual and interpretative abilities

“…Several of these measures were collected as part of battery administered to the University of Iowa TBI registry patients (Rigon, Duff, McAuley, Kramer, & Voss, 2016; Rigon, Turkstra, et al, 2016; Rigon, Turkstra, Mutlu, & Duff, In press; Rigon, Voss, et al, 2016). Due to study attrition, results for WAIS, CVLT, Trails, and BSI were missing from one participant in the HC group.…”

Relationship between individual differences in functional connectivity and facial-emotion recognition abilities in adults with traumatic brain injury

“…Structural connectivity following TBI has traditionally been examined using diffusion tensor imaging (DTI), which provides a way to assess integrity and directionality of white matter tracts traveling between nodes of a given brain network (Hulkower et al, 2013, Kennedy et al, 2009, Sharp and Ham, 2011). However, in the past decade several studies have employed resting state functional connectivity (rs-FC) measured with functional magnetic resonance imaging (fMRI) to investigate integrity of brain networks in TBI populations (Arenivas et al, 2014, Bonnelle et al, 2011, Marquez de la Plata et al, 2011, Palacios et al, 2013, Rigon et al, 2016a, Sharp et al, 2011). Rs-FC measures the correlation between fluctuations in the hemodynamic fMRI signal between regions throughout the brain that form large-scale brain networks (Biswal et al, 1995, Fox et al, 2005).…”

“…To date, a wealth of studies have found abnormalities in both white matter integrity (Hulkower et al, 2013, Sidaros et al, 2008) and patterns of rs-FC in several large-scale brain networks in TBI populations (Rigon et al, 2016a, Stevens et al, 2012), as well as correlations between these measures and behavioral performance (Bonnelle et al, 2011, Ham et al, 2014, Sours et al, 2014, Rigon et al, 2016c). However, only one study has explored the relationship between white matter integrity and facial-affect recognition ability in individuals with moderate-severe TBI: Genova and colleagues (Genova et al, 2015) found that performance on emotion recognition tasks was positively correlated with fractional anisotropy of the inferior fronto-occipital and inferior longitudinal fasciculus, which connect visual regions with temporal and prefrontal areas involved in affective processing and decision making.…”