Study tracks size of social brain areas across adolescence
Researchers have charted the normal development of what’s known as the social brain from childhood to young adulthood, according to research presented Sunday at the 2012 Society for Neuroscience annual meeting in New Orleans.
The social brain includes several regions known to be involved in social behavior and communication, some of which have been linked to autism.
The regions include the temporoparietal junction, or TPJ, activated when inferring what someone else is thinking — a skill called theory of mind — and the posterior superior temporal sulcus, or pSTS, which is sensitive to biological motion, such as movements made by someone walking or talking.
Social interactions become more complex during adolescence, notes Kate Mills, a graduate student in Sarah-Jayne Blakemore’s lab at University College London who presented the work.
“Along with an increase in self-consciousness, the opinions of peers become highly valued during adolescence,” Mills says. “So it’s unsurprising that social cognition, and in particular our ability to understand and read the intentions, beliefs and desires of others, is still developing.”
The researchers performed magnetic resonance imaging on 288 healthy individuals ranging in age from 7 to 30 years. All participants were scanned at two different time points at least, and some came in for as many as seven scans. The study is the longest ongoing study of brain development.
Three social brain areas — the TPJ, pSTS and the medial prefrontal cortex — peak in size before age 10 and then decline until the mid 20s, the researchers found. A fourth area, the anterior temporal cortex, or ATC, increases in volume until about age 13 and then declines. The thickness of the ATC increases until the late teens.
The ATC is activated when applying general knowledge about social situations to a specific circumstance. “It’s possible that this ongoing change in ATC may reflect a longer period of learning social scripts in our environment,” Mills says.
This kind of long-term data on healthy individuals could help build a framework for later studies of the social brain in autism. “Now that researchers investigating autism are pooling together their MRI datasets, sample sizes are probably big enough to do something similar to what we've done in a sample of individuals with autism,” Mills says.
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