Aim 8.1: To determine if cognitive score changes (1.0) correlate with clinical score changes (2.0) in an observational study of individuals with a history of TBI. Aim 8.2: To determine if cognitive score changes (1.0) correlate with imaging connectivity changes in an observational study of individuals with a history of TBI. Aim 8.3: To determine if clinical score changes (2.0) correlate with imaging connectivity changes in an observational study of individuals with a history of TBI. Aim 8.4: To determine if TBI history (score from OSU-TBI/BAT-L) predicts changes in brain connectivity changes (resting state fMRI) in an observational study of individuals with a history of TBI. Aim 8.5: To determine if TBI history (score from OSU-TBI/BAT-L) predicts changes in cognitive scores (1.0) in an observational study of individuals with a history of TBI. Aim 8.6: To determine if TBI history (score from OSU-TBI/BAT-L) predicts changes in clinical scores (2.0) in an observational study of individuals with a history of TBI. Aim 8.7: To determine if TBI history (score from OSU-TBI/BAT-L) predicts changes in cerebral perfusion (ASL) from baseline to immediate post treatment in an observational study of individuals with a history of TBI. Aim 8.8: To determine if TBI history (score from OSU-TBI/OSU-BAT-L) predicts changes in cerebral perfusion (ASL) from baseline to one-month post treatment in an observational study of individuals with a history of TBI. Aim 8.9: To determine the effect of ibogaine treatment on whole brain connectivity as measured by changes in connectivity patterns of brain networks from baseline to one-month post treatment in an observational study of individuals with history of TBI. Aim 8.10: To determine the effect of ibogaine treatment on whole brain EEG power measured by changes in connectivity patterns of brain networks from baseline to one-month post treatment in an observational study of individuals with history of TBI. 9. Exploratory: Structural Aim 9.1. To test the following hypothesis: Using the AFQ method, at baseline, TBI participants will differ from HCs by displaying significantly reduced FA in frontal fiber tracts, including the following: 1) cingulum bundle, 2) uncinate fasciculus, 3) superior longitudinal fasciculus, 4) inferior longitudinal fasciculus, and the 5) anterior thalamic radiation. Note: for hypothesis justifications see https://onlinelibrary.wiley.com/doi/epdf/10.1002/hbm.23365 and https://doi.org/10.1016/j.ynirp.2021.100047 (note: this hypothesis was registered after data collection but prior to the specific analysis described here). Aim 9.2. To test the following hypothesis: Using the AFQ method, at baseline, TBI participants will differ from HCs by displaying significantly reduced FA in the following fiber tracts: 1) the suprachiasmatic nucleus, 2) paraventricular nucleus, 3) optic tract (optic chiasm + left and right lateral geniculate) 4) optic nerve, and the 5) retinohypothalamic tract. Note: for hypothesis justifications see: https://www.sciencedirect.com/science/article/pii/B9780128093245023919 and https://www.sciencedirect.com/science/article/abs/pii/B9780444529039000145 and https://www.sciencedirect.com/science/article/abs/pii/S0010945219300309?via%3Dihub and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3482689/ and https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0046204 and https://www.mdpi.com/2079-7737/11/7/1031/pdf (note: this hypothesis was registered after data collection but prior to the specific analysis described here).