Timothy B. Meier

YNICL Journal 2025 Journal Article

A one year longitudinal study of cortical myelination changes following pediatric mild traumatic brain injury

• Jessica R. McQuaid
• Tracey V. Wick
• Josef Ling
• Andrew B. Dodd
• Divyasree Sasi Kumar
• Upasana Nathaniel
• Samuel D. Miller
• Vadim Zotev

The impact of pediatric mild traumatic brain injury (pmTBI) on cortical (i. e. , grey matter) myelination is not yet understood, especially for interactions with neurodevelopment. The current study examined the impact of pmTBI on cortical myelination relative to healthy controls (HC) by estimating myelin content using the T1w/T2w ratio method. Data were obtained from pmTBI (N = 217) participants at approximately 7 days (Visit 1 [V1]), 4 months (Visit 2 [V2]), and 1 year (Visit 3 [V3]) post-injury, with equivalent sampling points for age and sex-matched HC (N = 180). Clinical results suggested only partial recovery from post-concussive symptoms from V1 to V3, with similar incomplete recovery of sleep, functional outcomes, behavior, and long-term memory. Myelin content increased with chronological age and as a function of individual aging across study visits in a hemisphere specific fashion (left > right), most visibly within the posterior parietal lobe. Myelin content was also greater for females relative to males. There was evidence of both a reduction in myelination within the posterior parietal cortex for the pmTBI group at 4 months post-injury, as well as evidence of increased myelination within the left prefrontal cortex at one-year post-injury. However, neither of these findings survived various sensitivity analyses, suggesting that there were minimal effects of pmTBI on cortical myelin content in general. In summary, although rapid changes in myelin content existed as a function of neurodevelopment, there was little evidence to suggest that pmTBI permanently altered cortical myelin development trajectories.

YNICL Journal 2020 Journal Article

Amygdala response to emotional faces in adolescents with persistent post-concussion symptoms

• Luisa Bohorquez-Montoya
• Lezlie Y. España
• Amy M. Nader
• Robyn E. Furger
• Andrew R. Mayer
• Timothy B. Meier

Approximately 30% of adolescents with concussion develop persistent post-concussion symptoms (PPCS) that include emotional symptoms. Elevated amygdalae reactivity to emotional faces has been reported in a variety of psychopathologies characterized by emotional symptoms overlapping with those in PPCS. We tested the hypothesis that amygdalae reactivity to emotional faces in adolescents with PPCS+ is elevated compared to concussed adolescents without PPCS and healthy controls. Concussed adolescents (ages 14-18) with (PPCS+; n = 23) and without PPCS (PPCS-; n = 13) participated in visits at least 4 weeks post-injury. Adolescents without prior concussion served as controls (HC; n = 15). All participants completed a detailed clinical battery and a common emotional face processing task that involved matching of emotional faces or shapes. Compared to HC and PPCS-, adolescents with PPCS+ had elevated depression symptoms, anhedonia, general psychological symptoms, and anxiety symptoms. Contrary to our hypothesis, PPCS+ had lower amygdalae activity to the emotional faces versus shapes condition relative to HC and a trend for lower activity relative to PPCS-. There was a non-significant inverse association between anhedonia amygdalae activity in adolescents with PPCS. Results suggest that adolescents with PPCS have altered amygdalae activity during the processing of emotional face stimuli.

YNICL Journal 2018 Journal Article

Association of acute depressive symptoms and functional connectivity of emotional processing regions following sport-related concussion

• William T. McCuddy
• Lezlie Y. España
• Lindsay D. Nelson
• Rasmus M. Birn
• Andrew R. Mayer
• Timothy B. Meier

Acute mood disturbance following sport-related concussion is common and is known to adversely affect post-concussion symptoms and recovery. The physiological underpinnings of depressive symptoms following concussion, however, are relatively understudied. We hypothesized that functional connectivity of the emotional processing network would be altered in concussed athletes and associated with the severity of depressive symptoms following concussion. Forty-three concussed collegiate athletes were assessed at approximately one day (N = 34), one week (N = 34), and one month post-concussion (N = 30). Fifty-one healthy contact-sport athletes served as controls and completed a single visit. The Hamilton Rating Scale for Depression (HAM-D) was used to measure depressive symptoms. Resting state fMRI data was collected on a 3 T scanner (TR = 2 s) and functional connectivity was calculated in a meta-analytically derived network of regions associated with emotional processing. Concussed athletes had elevated depressive symptoms across the first month post-concussion relative to control athletes, but showed partial recovery by one month relative to more acute visits (ps < 0. 05). Concussed athletes had significantly different connectivity in regions associated with emotional processing at one month post-concussion relative to one day post-concussion (p = 0. 002) and relative to controls (p = 0. 003), with higher connectivity between default mode and attention regions being common across analyses. Additionally, depressive symptoms in concussed athletes at one day (p = 0. 003) and one week post-concussion (p = 7 × 10−8) were inversely correlated with connectivity between attention (e. g. , right anterior insula) and default mode regions (e. g. , medial prefrontal cortex). Finally, the relationships with HAM-D scores were not driven by a general increase in somatic complaints captured by the HAM-D, but were strongly associated with mood-specific HAM-D items. These results suggest that connectivity of emotional processing regions is associated with acute mood disturbance following sport-related concussion. Increased connectivity between attention and default mode regions may reflect compensatory mechanisms.

YNIMG Journal 2013 Journal Article

The effect of resting condition on resting-state fMRI reliability and consistency: A comparison between resting with eyes open, closed, and fixated

• Rémi Patriat
• Erin K. Molloy
• Timothy B. Meier
• Gregory R. Kirk
• Veena A. Nair
• Mary E. Meyerand
• Vivek Prabhakaran
• Rasmus M. Birn

Resting-state fMRI (rs-fMRI) has been demonstrated to have moderate to high reliability and produces consistent patterns of connectivity across a wide variety of subjects, sites, and scanners. However, there is no one agreed upon method to acquire rs-fMRI data. Some sites instruct their subjects, or patients, to lie still with their eyes closed, while other sites instruct their subjects to keep their eyes open or even fixating on a cross during scanning. Several studies have compared those three resting conditions based on connectivity strength. In our study, we assess differences in metrics of test–retest reliability (using an intraclass correlation coefficient), and consistency of the rank-order of connections within a subject and the ranks of subjects for a particular connection from one session to another (using Kendall's W tests). Twenty-five healthy subjects were scanned at three different time points for each resting condition, twice the same day and another time two to three months later. Resting-state functional connectivity measures were evaluated in motor, visual, auditory, attention, and default-mode networks, and compared between the different resting conditions. Of the networks examined, only the auditory network resulted in significantly higher connectivity in the eyes closed condition compared to the other two conditions. No significant between-condition differences in connectivity strength were found in default mode, attention, visual, and motor networks. Overall, the differences in reliability and consistency between different resting conditions were relatively small in effect size but results were found to be significant. Across all within-network connections, and within default-mode, attention, and auditory networks statistically significant greater reliability was found when the subjects were lying with their eyes fixated on a cross. In contrast, primary visual network connectivity was most reliable when subjects had their eyes open (and not fixating on a cross).

YNIMG Journal 2013 Journal Article

The effect of scan length on the reliability of resting-state fMRI connectivity estimates

• Rasmus M. Birn
• Erin K. Molloy
• Rémi Patriat
• Taurean Parker
• Timothy B. Meier
• Gregory R. Kirk
• Veena A. Nair
• M. Elizabeth Meyerand

There has been an increasing use of functional magnetic resonance imaging (fMRI) by the neuroscience community to examine differences in functional connectivity between normal control groups and populations of interest. Understanding the reliability of these functional connections is essential to the study of neurological development and degenerate neuropathological conditions. To date, most research assessing the reliability with which resting-state functional connectivity characterizes the brain's functional networks has been on scans between 3 and 11min in length. In our present study, we examine the test–retest reliability and similarity of resting-state functional connectivity for scans ranging in length from 3 to 27min as well as for time series acquired during the same length of time but excluding half the time points via sampling every second image. Our results show that reliability and similarity can be greatly improved by increasing the scan lengths from 5min up to 13min, and that both the increase in the number of volumes as well as the increase in the length of time over which these volumes was acquired drove this increase in reliability. This improvement in reliability due to scan length is much greater for scans acquired during the same session. Gains in intersession reliability began to diminish after 9–12min, while improvements in intrasession reliability plateaued around 12–16min. Consequently, new techniques that improve reliability across sessions will be important for the interpretation of longitudinal fMRI studies.

YNIMG Journal 2012 Journal Article

Support vector machine classification and characterization of age-related reorganization of functional brain networks

• Timothy B. Meier
• Alok S. Desphande
• Svyatoslav Vergun
• Veena A. Nair
• Jie Song
• Bharat B. Biswal
• Mary E. Meyerand
• Rasmus M. Birn