How do brain connections change during teenage puberty?
As young people grow up, connections between emotional brain centers and thinking brain regions weaken, a process driven more by puberty than age.
Source
A three-wave longitudinal study of subcortical-cortical resting-state connectivity in adolescence: Testing age- and puberty-related changes
What they did
Researchers tracked 273 participants aged 8 to 29 over three testing waves. They measured resting-state functional magnetic resonance imaging to look at brain connectivity and used the self-reported Pubertal Development Scale to evaluate physical maturity. The study focused on the functional coupling between subcortical structures like the nucleus accumbens and amygdala, and cortical regions of the medial prefrontal cortex.
What they found
The study found that a quarter of the connections between deep subcortical structures and the prefrontal cortex weakened over time, whereas connections within cortical networks and within subcortical networks became stronger. Crucially, pubertal development was a better predictor of this decoupling than chronological age for several major neural pathways, such as the connection between the nucleus accumbens and the frontal medial cortex in boys. For girls, physical puberty predicted decreased connectivity between the caudate and the dorsal anterior cingulate cortex even after accounting for their starting age.
The limits
What it doesn't show
While this longitudinal study demonstrates physical changes over time, it cannot establish whether pubertal hormones directly cause these neural changes or if they are co-occurring processes. The puberty measurements relied on a subjective self-report questionnaire rather than objective hormone levels, which may introduce reporting bias or inaccuracies. Furthermore, the individual consistency of the brain scans over time was relatively low, with intraclass correlation values ranging between 0.08 and 0.33, meaning individual differences in development remain difficult to track reliably with this method.
Key terms
- resting-state functional magnetic resonance imaging
- A neuroimaging method used to evaluate regional interactions in the brain when a person is not performing an explicit task.
- subcortical-cortical connectivity
- The functional communication and network pairing between deep, older brain structures and the outer cerebral cortex.
- generalized additive mixed models
- Flexible statistical models that can capture complex, non-linear relationships in data while accounting for repeated measures from the same individuals.
- intraclass correlation
- A descriptive statistic used to measure how reproducible or stable individual measurements are within a group over multiple time points.
- nucleus accumbens
- A key subcortical brain structure located in the ventral striatum that is heavily involved in reward processing, motivation, and decision-making.
- Pubertal Development Scale
- A self-report questionnaire that assesses physical maturation by measuring secondary sexual characteristics in adolescents.
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Quiz yourself
Which statistical modeling framework did the researchers utilize to capture non-linear developmental trajectories of resting-state functional connectivity without the constraints of rigid geometric shapes?
Common questions
Why did the researchers use resting-state fMRI instead of a task-based scan?
Resting-state scans require minimal experimental effort from participants, making it easier to compare brain activity across a wide age range from children to young adults without performance differences biasing the results.
Why does the study separate its pubertal analyses for boys and girls?
Puberty occurs at different ages and moves at different speeds for boys and girls, meaning combining them would obscure the distinct timelines and trajectories of physical maturation unique to each sex.
How did the researchers handle head motion in the brain scanner?
They used a mock scanner to train participants beforehand, excluded scans with absolute movements over 2 millimeters, and used advanced software filtering to clean remaining motion noise from the data.
What does the 'decoupling' of subcortical and cortical regions actually mean for teenagers?
It suggests that emotional and motivational centers in the deep brain begin to function more independently from thinking and control regions in the cortex, which is thought to represent a step toward adult-like brain efficiency.
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