Mild Traumatic Brain Injury Disrupts Functional Dynamic Attractors of Healthy Mental States

The human brain has the ability of changing its wiring configuration by increasing or decreasing functional connectivity strength between specific areas. Variable but recurring configuration patterns in dynamic functional connectivity have been observed during resting fMRI experiments, patterns which are defined as dynamic brain states. The question arises whether in a regular healthy brain these states evolve in a random fashion or in a specific sequential order. The current work reveals both the specific state sequence in healthy brains, as well as the set of disruptions in this sequence produced by traumatic brain injury. The healthy sequence consists of oscillatory dynamic connectivity patterns that orbit an attractor state in a high dimensional space. Using discovery (96 subjects) and replication (74 subjects) cohorts, this study demonstrated that mild traumatic brain injury results in immediate orbital disruptions that recover over time. Brain dynamics enter a status of disrupted orbits right after injury, with partial recovery at 4 weeks, and full recovery at 3 months post-injury. In summary, our results describe an aspect of neuronal dysfunction in mild traumatic brain injury that is fully based on brain state dynamics, and different from traditional brain connectivity strength measures.