Developmental Mismatches in Amygdala and PFC Macrostructure and White Matter Tract Integrity
Poster No:
1245
Submission Type:
Abstract Submission
Authors:
Jamie Roeske1, Xiangyu Long1, Meaghan Perdue1, Madison Long1, Bryce Geeraert1, Mohammad Ghasoub1, Catherine Lebel1
Institutions:
1University of Calgary, Calgary, Alberta
First Author:
Co-Author(s):
Introduction:
Brain development varies regionally, with the volumes of subcortical regions like the amygdala plateauing before prefrontal cortex (PFC) volumes. The development of white matter tracts that terminate in the PFC has also been shown to plateau later than other major tracts. As theories like the Developmental Mismatch Hypothesis propose that differences in amygdala and PFC developmental rates drive behaviour development, studying the developmental trajectories of these regions is critical to understanding behaviour and the causes of neurodevelopmental disorders. While previous work has established that amygdala and PFC macrostructural trajectories are mismatched, findings are limited by small sample sizes (~n=30) and do not include the period of most dramatic development, birth to 5 years of age. Few studies have investigated macrostructure and tract integrity within the same sample, with amygdala-PFC connectivity particularly overlooked. Here, we used a large longitudinal dataset to characterize and compare amygdala and PFC volumes and amygdala-PFC tract integrity trajectories in children and adolescents.
Methods:
518 magnetic resonance imaging (MRI) scans from 95 typically developing participants aged 1.95-12.99 were included (48 females). T1 (FSPGR BRAVO, 0.9mm isotropic voxels, TR=8.23ms, TE=3.76ms) and diffusion-weighted (spin-echo EPI, 1.6x1.6x2.2mm voxels, TR=6750ms, TE=79ms, 5 b=0 s/mm2 volumes, 30 b=750 s/mm2 volumes) scans were acquired on a 3T GE Discovery MR750w system with a 32-channel head coil at the Alberta Children's Hospital. Advanced Normalization Tools (ANTs) and Analysis of Functional Neuroimages (AFNI) were used to perform an N4 bias correction and 1mm voxel size resampling, respectively, on raw T1 scans. Preprocessed T1 scans were segmented using Multi-atlas Cortical Reconstruction Using Implicit Surface Evolution (MaCRUISE), and amygdala and PFC (middle frontal gyrus (MFG), inferior frontal gyrus (IFG), frontal pole (FP)) volumes were extracted. Diffusion images were preprocessed in ExploreDTI, and then semiautomated deterministic tractography was performed to isolate the amygdala-PFC tract in each hemisphere. Mean fractional anisotropy (FA) and mean diffusivity (MD) were computed for each tract. Volumes and tract metrics were standardized to Z-scores across the full study cohort. Trajectories were modelled using generalized additive mixed effects models (GAMMs) from the mgcv package in RStudio. Age, age+sex, and age*sex models were tested for each metric bilaterally. All volume models contained intracranial volume as a covariate. Models with the lowest Bayesian information criterion values were selected. Metric developmental rates were calculated from the first derivative of the GAMM trendlines. Periods with significant age-related change had first derivative 95% confidence intervals that excluded zero.
Results:
Significant age effects were found for all metrics (Figures 1 and 2). Bilateral amygdala volume gradually increased between ages 1.95-5.28. Left amygdala volume decreased slightly between ages 7.89-9.16. Bilateral MFG volume steadily decreased across the age span. Right IFG volume increased slightly between ages 3.23-4.22. Bilateral IFG and FP volumes steadily decreased between 5.06-12.99 years and 5.33-12.99 years, respectively. Bilateral tract FA increased rapidly at early ages and then more gradually across the age span. Bilateral tract MD decreased rapidly at early ages and plateaued by 10.44 years.
Conclusions:
Our findings show that amygdala, PFC, and amygdala-PFC tract trajectories are qualitatively mismatched. Amygdala development predominantly occurred in early childhood, while PFC development occurred in late childhood and early adolescence. The amygdala-PFC white matter tract changed most in early childhood and showed larger changes than amygdala and PFC volumes. Future directions include expanding the age range up to age 17 and relating mismatches to behaviour development.
Lifespan Development:
Early life, Adolescence, Aging 1
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
Anatomy and Functional Systems
Normal Development
White Matter Anatomy, Fiber Pathways and Connectivity
Novel Imaging Acquisition Methods:
Multi-Modal Imaging 2
Keywords:
Development
MRI
NORMAL HUMAN
STRUCTURAL MRI
Tractography
WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
Other - Amygdala; Prefrontal Cortex; Developmental Trajectories; Generalized Additive Mixed Effects Models
1|2Indicates the priority used for review
Provide references using author date format
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