The aim of this study was to investigate if discrete wavelet decomposition provides additional insight into resting-state processes through the analysis of functional connectivity within specific frequency ranges within the default mode network (DMN) that may be affected by mild traumatic brain injury (mTBI). Participants included 32 mTBI patients (15 with postconcussive syndrome [PCS + ] and 17 without [PCSÀ]). mTBI patients received resting-state functional magnetic resonance imaging (rs-fMRI) at acute (within 10 days of injury) and chronic (6 months postinjury) time points and were compared with 31 controls (healthy control [HC]). The wavelet decomposition divides the time series into multiple frequency ranges based on four scaling factors (SF1: 0.125-0.250 Hz, SF2: 0.060-0.125 Hz, SF3: 0.030-0.060 Hz, SF4: 0.015-0.030 Hz). Within each SF, wavelet connectivity matrices for nodes of the DMN were created for each group (HC, PCS + , PCSÀ), and bivariate measures of strength and diversity were calculated. The results demonstrate reduced strength of connectivity in PCS + patients compared with PCSÀ patients within SF1 during both the acute and chronic stages of injury, as well as recovery of connectivity within SF1 across the two time points. Furthermore, the PCSÀ group demonstrated greater network strength compared with controls at both time points, suggesting a potential compensatory or protective mechanism in these patients. These findings stress the importance of investigating resting-state connectivity within multiple frequency ranges; however, many of our findings are within SF1, which may overlap with frequencies associated with cardiac and respiratory activities.

Preplaced landmarks yielded good IOR and IOA in quantitative assessment of AS structures that were NTD and non-CB-related or less removed from the reference. CB-related NTD measurements varied greatly in IOR and IOA, indicating protocol modifications or CB qualitative assessments needed to improve accuracy. Variability in TD measurements increased the further removed from the reference, which supports implementation of a reliable reference landmark to minimize variation.

No abstract