How does the brain's outer layer change during adolescence?

What were the two primary aims of this multisample longitudinal study?

The study aimed to characterize regional developmental trajectories of cortical volume, surface area, and thickness during adolescence, and to test how changes in these metrics are inter-related.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Which four independent longitudinal datasets were analyzed in this study?

The study analyzed the Child Psychiatry Branch (CPB), Pittsburgh (PIT), Neurocognitive Development (NCD), and Braintime (BT) datasets.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How many total participants and scans across what age range were included in the final combined dataset?

The final analysis included 388 participants (199 females) and 854 scans covering an age range of 7 to 29 years.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Which software platform and stream were used for processing the T1-weighted longitudinal scans?

The T1-weighted scans were processed using FreeSurfer 5.3's longitudinal stream, which creates an unbiased within-subject template.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What type and size of smoothing kernel were applied to the reconstructed cortical surface maps?

A Gaussian kernel of full-width at half-maximum (FWHM) of 15 mm was used to smooth the surface maps.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How is the Symmetrized Annual Percentage Change (APC) defined in this study?

APC is defined as the linear annual rate of change relative to the average of the volume, area, or thickness measures across all available time points.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Why did the researchers use generalized additive mixed models (GAMM) for trajectory curve fitting?

GAMM avoids the weaknesses of polynomial models (like quadratic or cubic models) where the timing of peaks and end points can be biased by the sampled age range.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How was multiple comparison correction handled for the vertex-wise analyses across the cortical surface?

Vertex-wise analyses were corrected using Z Monte Carlo simulations (10,000 iterations) to test against an empirical null distribution of maximum cluster size, with a cluster-wise threshold of p < 0.05.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What general developmental trajectory did total cortical volume show across the age range of 7 to 29 years?

Total cortical volume decreased across the entire age range in all four samples, with slightly accelerated decreases observed during the adolescent period.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What general developmental trajectory was observed for total cortical surface area across the four samples?

Total cortical surface area showed nearly linear decreases across all four samples during late childhood and adolescence.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What developmental trajectory characterized mean cortical thickness across late childhood and adolescence?

Mean cortical thickness showed highly overlapping, nonlinear trajectories with accelerated thinning during the adolescent period.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Among cortical volume, surface area, and thickness, which measure exhibited the largest annual percentage decrease?

Cortical volume showed the largest annual percentage decrease (average APC of -1.43), followed by thickness, and then surface area.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Which cortical lobe consistently showed the largest developmental decreases in volume, surface area, and thickness?

The parietal lobe consistently showed the largest decreases across all three structural measures in all four samples.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Which lobe consistently showed the smallest developmental decrease in cortical thickness across all samples?

The occipital lobe consistently showed the smallest decrease in cortical thickness.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What regional exceptions to the general pattern of cortical volume reductions were observed on the vertex-wise surface maps?

Significant volume increases or lack of changes were noted around the central sulcus, in the insular cortex, and in the medial temporal and medial occipital cortices.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How strongly correlated were developmental changes in cortical thickness and cortical volume?

All samples showed very strong, positive correlations (r = 0.72 to 0.95) between cortical thickness change and volume change globally and across all lobes.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What is the primary contributor to developmental reductions in cortical volume during adolescence?

Cortical thinning is the dominant contributor to cortical volume reductions during adolescence, despite surface area explaining most individual differences in adult brain size.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How do developmental relationships between surface area and thickness changes vary across cortical topology?

Changes in surface area and thickness are positively associated in sulcal regions (e.g., prefrontal and temporal sulci) and negatively associated in gyral and insular regions.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What do positive and negative statistical relationships between surface-area and thickness changes physically represent?

Since both measures generally decrease, positive relationships mean greater area reductions are linked to greater thinning; negative relationships mean greater area reductions are linked to less thinning.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Did this study find evidence of an adolescent ‘peak’ in cortical volume, thickness, or surface area?

No, none of the four samples showed a global increase or developmental peak for cortical volume, surface area, or thickness between ages 7 and 29.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI

To what did the authors attribute prior inconsistent findings regarding adolescent cortical trajectories?

They suggested inconsistencies arise from differences in image processing streams, quality control (QC) procedures, and statistical curve-fitting methods rather than differences in samples or scanners.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

Why is head motion a particularly problematic confounding factor in developmental MRI studies?

Head motion artificially reduces estimates of cortical thickness and volume. Since younger participants tend to move more, motion is systematically confounded with age.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What occurs to cortical thickness developmental models when low-quality scans (QC failures) are included in the dataset?

Including lower-quality scans shifts the developmental models toward artificially complex trajectories, emphasizing the critical role of rigorous quality control.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What is the ‘stretching’ hypothesis regarding the relationship between myelination and cortical structure?

The hypothesis proposes that intracortical myelination and axonal caliber growth cause the cortex to stretch tangentially, which expands its surface area while simultaneously making it thinner.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

What is the ‘tension release’ hypothesis regarding synaptic pruning and cortical surface area?

This hypothesis states that synaptic pruning and dendritic changes reduce axonal tension, which leads to decreased cortical folding (gyrification) and flattening of the cortex.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified

How did sample size impact the detection of topological relationships between surface-area and thickness changes?

Spatially widespread relationships, especially negative associations, were highly dependent on sample size, showing the most extensive effects in the largest sample and very limited effects in smaller samples.

Source: Development of the Cerebral Cortex across Adolescence: A Multisample Study of Inter-Related Longitudinal Changes in Cortical Volume, Surface Area, and Thickness · DOI · quote verified