Thalamo-Prefrontal Connectivity Correlates With Early Command-Following After Severe Traumatic Brain Injury

Abstract

Recovery of consciousness after traumatic brain injury (TBI) is heterogeneous and difficult to predict. Structures such as the thalamus and prefrontal cortex are thought to be important in facilitating consciousness. We sought to investigate whether the integrity of thalamo-prefrontal circuits, assessed via diffusion tensor imaging (DTI), was associated with the return of goal-directed behavior after severe TBI. We classified a cohort of severe TBI patients (N = 25, 20 males) into Early and Late/Never outcome groups based on their ability to follow commands within 30 days post-injury. We assessed connectivity between whole thalamus, and mediodorsal thalamus (MD), to prefrontal cortex (PFC) subregions including dorsolateral PFC (dlPFC), medial PFC (mPFC), anterior cingulate (ACC), and orbitofrontal (OFC) cortices. We found that the integrity of thalamic projections to PFC subregions (L OFC, L and R ACC, and R mPFC) was significantly associated with Early command-following. This association persisted when the analysis was restricted to prefrontal-mediodorsal (MD) thalamus connectivity. In contrast, dlPFC connectivity to thalamus was not significantly associated with command-following. Using the integrity of thalamo-prefrontal connections, we created a linear regression model that demonstrated 72% accuracy in predicting command-following after a leave-one-out analysis. Together, these data support a role for thalamo-prefrontal connectivity in the return of goal-directed behavior following TBI.

Relationship between the consciousness level and the structural neural connectivity of the medial prefrontal cortex in hypoxic-ischemic brain injury: a pilot study

“…Thus, our results appear to be generally in line with the results of the previous fMRI and DTT-based studies mentioned above [11–19,23]. However, to the best of our knowledge, this is the first study to demonstrate the relationship between the consciousness level and the mPFC SNC in patients with HI-BI.…”

“…By using DTT, several case studies have demonstrated that the increased neural connectivity to the mPFC from the thalamic intralaminar nucleus in the ARAS was responsible for the recovery of impaired consciousness in patients with stroke (three patients) and HI-BI (two patients) [11][12][13][14][15]. Recently, Cosgrove et al [23] found that the integrity of the connections between the whole thalamus and the three subregions of the prefrontal cortex (mPFC, anterior cingulate cortex, and orbitofrontal cortex) was associated with the ability to follow commands in 25 patients with severe TBI.…”

“…Recently, Cosgrove et al . [23] found that the integrity of the connections between the whole thalamus and the three subregions of the prefrontal cortex (mPFC, anterior cingulate cortex, and orbitofrontal cortex) was associated with the ability to follow commands in 25 patients with severe TBI.…”

“…Several DTT-based case studies have demonstrated that the increased neural connectivity to the mPFC from the thalamus was responsible for the recovery of impaired consciousness in patients with stroke (three patients) and HI-BI (two patients) [11][12][13][14][15]. A recent original study reported that the integrity of the connectivity between the mPFC and thalamus was closely related to the 'obedience-to-command' in patients with TBI [23]. However, no original study involving a large number of patients, on the relationship between the consciousness level (or recovery outcome) and the SNC of the mPFC (mPFC SNC) in HI-BI, has so far been reported.…”

Relationship between the Consciousness State and the Default Mode Network in Traumatic Brain Injury

“…Fifth, we analysed only two tracts of the DMN among various neural networks for control of consciousness [13][14][15][16]19]. As a result, further studies including larger number of subjects and analysing other neural networks for control of consciousness should be encouraged; especially the neural networks including the thalamus which is a center for control of consciousness such as the thalamo-prefrontal connection [35][36][37].…”