Hyper-connectivity of the thalamus during early stages following mild traumatic brain injury

Abstract

The thalamo-cortical resting state functional connectivity of 7 sub-thalamic regions were examined in a prospectively recruited population of 77 acute mild TBI (mTBI) patients within the first 10 days (mean 6±3 days) of injury and 35 neurologically intact control subjects using the Oxford thalamic connectivity atlas. Neuropsychological assessments were conducted using the Automated Neuropsychological Assessment Metrics (ANAM). A subset of participants received a magentic resonance spectroscopy (MRS) exam to determine metabolite concentrations in the thalamus and posterior cingulate cortex. Results show that patients performed worse than the control group on various subtests of ANAM and the weighted throughput score, suggesting reduced cognitive performance at this early stage of injury. Both voxel and region of interest based analysis of the resting state fMRI data demonstrated that acute mTBI patients have increased functional connectivity between the various sub-thalamic regions and cortical regions associated with sensory processing and the default mode network (DMN). In addition, a significant reduction in NAA/Cr was observed in the thalamus in the mTBI patients. Furthermore, an increase in Cho/Cr ratio specific to mTBI patients with self-reported sensory symptoms was observed compared to those without self-reported sensory symptoms. These results provide novel insights into the neural mechanisms of the brain state related to internal rumination and arousal, which have implications for new interventions for mTBI patients with persistent symptoms. Furthermore, an understanding of heightened sensitivity to sensory related inputs during early stages of injury may facilitate enhanced prediction of safe return to work.

The effect of preprocessing in dynamic functional network connectivity used to classify mild traumatic brain injury

“…Decreased occupancy for State 3, where subcortical networks had a more negative dFNC value, might affect overall subcortical connectivity. This provide evidence for a thalamic abnormality based on increased functional connectivity as it has been previously reported in the literature (Sours, George, Zhuo, Roys, & Gullapalli, 2015; Tang et al., 2011). This is reflected in State 2 where the thalamus has positive correlations with other RSNs in the default mode and the cerebellum groups.…”

“…This is reflected in State 2 where the thalamus has positive correlations with other RSNs in the default mode and the cerebellum groups. This correlation enhancement can be explained by a compensatory mechanism for detrimental sensorial symptoms in mTBI patients (Sours et al., 2015). Structural corticothalamic abnormalities of white matter in TBI patients are linked to more serious symptoms including posttraumatic stress disorder (Yeh et al., 2014).…”

Thalamic Functional Connectivity in Mild Traumatic Brain Injury: Longitudinal Associations With Patient-Reported Outcomes and Neuropsychological Tests

“…5–9 The thalamus functions as a sensory relay center with projections to multiple cortical regions. 10 Prior studies show the thalamus is susceptible to injury and can result in decreased volume, 11, 12 inflammation, 13 and reduced perfusion.…”

“…15, 16 Recently, functional MRI (fMRI) has been used for characterizing brain-related changes in conditions like mTBI. 6, 8 Using fMRI, Iraji et al 6 and Sours et al 9 found increased functional connectivity (FC) between thalamic and other brain areas in patients with mTBI. These studies offer early evidence that alterations in thalamic FC may be linked to clinical deficits of mTBI.…”

Art therapy and underlying fMRI brain patterns in military TBI: A case series

“…One potential candidate for a brain trauma central biomarker is the thalamus (Nathan, Ollinger, Bonavia, & Riedy, 2016;Nathan et al, 2012;Sours, George, Zhuo, Roys, & Gullapalli, 2015;Tang et al, 2011). The thalamus is a focal point at which many brain connections converge.…”