Abstract
Neuroelectric measures derived from human magnetoencephalographic (MEG) recordings hold promise as aides to diagnosis and treatment monitoring and targeting for chronic sequelae of traumatic brain injury (TBI). This study tests novel MEG-derived regional brain measures of tonic neuroelectric activation for long-term test-retest reliability and sensitivity to symptoms. Resting state MEG recordings were obtained from a normative cohort, Cambridge Centre for Ageing and Neuroscience (CamCAN), baseline: n = 619; mean 16-month follow-up: n = 253) and a chronic symptomatic TBI cohort, Targeted Evaluation, Action and Monitoring of Traumatic Brain Injury (TEAM-TBI), baseline: n = 64; mean 6-month follow-up: n = 39). For the CamCAN cohort, MEG-derived neuroelectric measures showed good long-term test-retest reliability for most of the 103 automatically identified stereotypic regions. The TEAM-TBI cohort was screened for depression, somatization, and anxiety with the Brief Symptom Inventory and for insomnia with the Insomnia Severity Index. Linear classifiers constructed from the 103 regional measures from each TEAM-TBI cohort member distinguished those with and without each symptom, with p < 0.01 for each—i.e., the tonic regional neuroelectric measures of activation are sensitive to the presence/absence of these symptoms. The novel regional MEG-derived neuroelectric measures obtained and tested in this study demonstrate the necessary and sufficient properties to be clinically useful—i.e., good test-retest reliability, sensitivity to symptoms in each individual, and obtainable using automatic processing without human judgement or intervention.
Highlights
The primary objective of this work was to obtain and validate clinically useful neuroelectric measures localized within the brain
The baseline and follow-up Team-Traumatic brain injury (TBI) z-scores were used to test for sensitivity to symptoms
The results reported here enable rejection of the following null hypotheses. (a) Individuals with and without symptoms are indistinguishable. (b) The cohort membership of each individual (TEAM-TBI or Cambridge Centre for Ageing and Neuroscience (CamCAN)) cannot be determined. (c) Regional measures from an individual do not reliably repeat. (d) Within the individual, the neuroelectric activity within a cortical region is indistinguishable from the adjacent rim of white matter
Summary
Traumatic brain injury (TBI) is a major cause of death and disability. Localized neuroelectric correlates of persistent functional sequelae after TBI would provide significant clinical value for diagnosis, disease monitoring, and targeted therapy. It has been the informed expectation for a century that the keys to understanding the human brain will be found in measuring and understanding the electrical activity of neurons. Clinical neurophysiologists routinely measure single neurons to aid implantation of therapeutic devices deep in the brain [1].
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