Tuesday, November 15, 2016

A Structural Difference between Boys' and Girls' Brains

The story comes to us from the Daily Mail. Where else? Before you begin scoffing, I will add that the research was conducted at Stanford University. It was published in a serious academic journal, called Depression and Anxiety.

The researchers wanted to study the different ways that the brains of boys and girls react to severe stress. While no one seems to want to say it, the question points at a significant biological difference between the sexes.

The difference concerns a part of the brain responsible for feelings and action, called the insula.  Wikipedia offers an explanation of its function:

The insulae are believed to be involved in consciousness and play a role in diverse functions usually linked to emotion or the regulation of the body's homeostasis. These functions include perceptionmotor controlself-awarenesscognitive functioning, and interpersonal experience. In relation to these, it is involved in psychopathology.

They discovered that when boys and girls are exposed to stress the girls’ insulae shrink while the boys’ insulae grow.

The Daily Mail reports:

Girls react differently to stress because it changes parts of their brain, new research suggests.

Traumatic situations cause the section of their brain responsible for feelings and actions - known as the insula - to shrink.

Whereas stress has the opposite effect on boys, causing theirs to grow.

Among the consequences, researchers believe that girls who are exposed to more stress might age more quickly and experience puberty earlier. Thus, that the stress is more damaging for them than for boys. And girls will have more difficulty dealing with certain kinds of extreme stress than boys.

Does this not tell us that men and women in the military probably react differently to extremely stressful situations? Thus, that women are more likely to be traumatized and more likely to have more difficulty functioning than men. The problem lies in the brain, not in a social construct.


Trigger Warning said...

Let me begin by saying that (1) men and women are biologically different, and (2), in my opinion, women have no business in military combat roles, irrespective of insulae, for a wide variety of reasons.

Having said that, fMRI results should be taken with large scoops, indeed shovelfuls, of salt. Understanding brain function using fMRI is akin to taking a satellite infrared scan of a factory roof and trying to figure out what is being made inside. There are obvious constraints on factory floor processes that help, but at the end of the day it's a futile pursuit, fraught with potential for error. Frankly, fMRI is a high-tech version of phrenology.

One major problem is that fMRI images are the result of mathematical signal processing algorithms. To get the pictures, numerical thresholds are set to determine which pixels with be red (active), and which pixels will be gray (inactive). The numerical thresholds are arbitrary. And, in fact, the images can look completely different merely as a function of different CPU chips because different chips handle floating-point operations differently. Like the beautiful Hubble images you see on the internet, raw fMRI "images", to the extent they should be called "images" at all before they are processed, look nothing like the pictures shown in journals (FYI, there is actually no color in those popular Hubble images you see on the internet - they are all "colorized" for your enjoyment. As NASA has noted, the colorization "is equal parts art and science".)

I raised the fMRI issue at a NATO conference many years ago, but no one listened. Nevertheless, in May of this year, PNAS published a study (Eklund, et al) that found "that the most common software packages for fMRI analysis (SPM, FSL, AFNI) can result in false-positive rates of up to 70%...". That is a stunning finding, and casts thousands of journal pages in serious doubt.

Beyond that, please note the Wiki entry quoted above carefully says that "The insulae are believed to be..." That's a guess. It's an educated guess, yes, but jeez... it was an "educated guess" that Hillary was 14 points ahead and that the Arctic would be ice-free last summer.

Despite the pop-sci appeal of fMRI imaging (and it seems all the cool kids with Federal grants have a machine these days), there is good reason to exclude women from some military roles. As I've noted here before, when I was told I would be paired with a woman in the volunteer fire department I served in, I explained I would be delighted to serve with her after she demonstrated an ability to carry me down a flight of stairs while wearing bunker gear. Otherwise, the battalion commander could go pound sand. Neither insulae nor fMRI imaging entered into my decision.

Ares Olympus said...

Stuart: Does this not tell us that men and women in the military probably react differently to extremely stressful situations? Thus, that women are more likely to be traumatized and more likely to have more difficulty functioning than men.

No, it's not clear at all that a study on boys and girls applies at all to men and women who are considering military service.

However it may suggest we should worry more about intervention with girls in unstable family situations.

If I look at my own family's stressful times, like with my parents yelling and fighting in the years before their divorce, I'm sure my sister took it harder than me. She convinced herself that she was a bad daughter and believed if she was good enough, they'd stop fighting and we could be a happy family again. I had no such delusions, correctly concluded that it was not my problem, and retreated to my own space.