When Does Maturity Set In?

An anonymous reader writes "Two Dartmouth researchers claim that they are one step closer to discovering at what age human maturity sets in. From the article: 'For the study, Baird and graduate student Craig Bennett looked at the brains of nineteen 18-year-old Dartmouth students who had moved more than 100 miles to attend college. A control group of 17 older students, ranging in age from 25 to 35, were also studied for comparison. The results indicate that significant changes took place in the brains of these individuals. The changes were localized to regions of the brain known to integrate emotion and cognition. Specifically, these are areas that take information from our current body state and apply it for use in navigating the world.'"

Comments

The problem with this post

[museumpeace]

is that NONE of us can RTFA. All that is posted here is the write-up by a Dartmouth PR person. The link to the journal article hits a roadblock unless you can toss it a Wiley Interscience license cookie...you may be lucky enough to be near a university library..you probably aren't. When I submitted this to the Agonist.org yesterday, I had such access. The paper is long, spends 2/3 of its pages clarifying and justifying its particular use of the somewhat controversialVBM technique and otherwise qualifying its results. The authors are fairly up front about distancing their work from claiming a universal result...how "average" could your findings be based only on 19 Dartmouth freshmen. [did they control for alcohol use?].

Even with all the disclaimers, they had two supportable contentions:

1. whatever change it is,[myelination was their pick] higly localized changes in brain areas that integrate emotion and decision ARE changeing.
2. their data do little to pick apart the nature vs nurture issues that may rule such changes...only supporting the conclusion that at 18 something is still rewiring your brain.

I am the first author

[benntop]

It is good to see a lot of thoughtful comments here regarding the paper.

If you have any questions for me specifically then please reply to this post and I will try to answer as directly as I can.

Best,
~Craig

Re:I am the first author

[benntop]

The linked Slashdot article is just the College Relations department press release. You can look at the full prepress PDF at the following address:

http://www.theteenbrain.com/about/publications/pdf s/2005-Bennett-VBM.pdf

Re:I am the first author

[benntop]

You couldn't be more correct about the press release.

The sample size of ~20 is small when compared to many other studies. Oddly enough though, it is above average for many MRI and fMRI experiments. Several of the studies we built off of have even smaller sample sizes. Gogtay et al., 2004*, a very good paper, had a sample size of 13! This doesn't justify the low number, but does give you an idea regarding normal study sizes.

We had wanted to end up with usuable data for 40 subjects. We scanned 50 subjects for our time1 acquisition, which we thought would be plenty to keep our numbers high after our time2 scan. In the end subject dropout, scanner breakdowns, and just plain old bad data conspired to limit the sample to 19.

* Gogtay, N. et al. Dynamic mapping of human cortical development during childhood through early adulthood. Proc Natl Acad Sci U S A 101, 8174-9 (2004).