Monday, September 20, 2010

Post #200!

Right now, this is the 200th post on this blog, though that will probably change once I finish up some very old posts in the draft queue --- some of which I'll want to keep backdated so that they will appear in chronological order as part of a series.

There's also another milestone I passed recently: this blog is now a little over three years old.

Two hundred posts over three years means I average about a post a week, with two every third week. Given how long it's taken me to write posts lately, that sounds incredible.

Wednesday, September 15, 2010

Through a (Brain) Scanner, Darkly

EXECUTIVE SUMMARY: In the August 11 issue of the Journal of Neuroscience, Christine Ecker and her colleagues at the Institute of Psychiatry at King's College in London describe a new tool they've developed for finding differences between autistic and non-autistic brains that go beyond "x brain structure is bigger/smaller in autistic people"; their method takes into account overall patterns of gray matter structure and organization. Their tool not only identifies these subtle, pervasive differences, it also "learns" them, using them to classify individual (computer models of) brains as autistic or not-autistic. The tool works quite well for that kind of classification, doing significantly better than chance on almost all its individual components, and reaching 65 to 85 percent accuracy as a whole. It can also distinguish between autistic brains and some other kind of non-neurotypical brain, in this case ADHD.

(Still image from the TV show "Dollhouse") Apart from this brief mention on Amanda's blog, I hadn't read anything at the time about the new multidimensional brain scan described last month in the Journal of Neuroscience. I was intrigued, because one thing that's been awfully elusive to autism researchers is a consistent, reproducible biological marker that's specific to autism.

There've been some hints of neuroanatomical differences between autistic and non-autistic people in previous studies, but those differences --- in, say, the size and activity of the amygdala, the size and shape of the hippocampus, the size of the cerebellar vermis, the distribution of gray matter and white matter, the density of certain cell types within the cerebellum, the thickness of the cerebral cortex, or even in the overall size of the brain --- don't always show up when researchers look for them, nor do they always show up in every member of the (very small, carefully selected and usually quite homogeneous) group of autistic people being studied.

The authors of the recent study --- Christine Ecker, Andre Marquand, Janaina Mourão-Miranda, Patrick Johnston, Eileen M. Daly, Michael J. Brammer, Stefanos Maltezos, Clodagh M. Murphy, Dene Robertson, Steven C. Williams and Declan G. M. Murphy --- suspect that there might be a broader, more pervasive pattern of altered brain structure that underlies all the different, highly variable, changes to individual structures within the brain that are sometimes seen in autism:
[R]eports of region-specific differences in ASD are highly variable [for review, see Toal et al. (2005) and Amaral et al. (2008)]. Such variable findings may simply be explained by confounds such as clinical heterogeneity between studies, or analytical techniques. Alternatively, variability in findings may indicate that differences in brain anatomy in ASD are relatively subtle and spatially distributed, and are difficult to detect using mass-univariate (i.e., voxelwise) approaches. Last, given the multiple etiology of ASD, it is likely that its neuroanatomy is not confined to a single morphological parameter but affects multiple cortical features.
To try to find out what kinds of subtle, structural differences might characterize the brains of autistic adults, the researchers scanned the brains of twenty autistic men*, twenty men without any psychiatric, neurological or developmental disorders, and nineteen men without autism but with ADHD (to provide a non-autism, but also non-neurotypical, control group to try and isolate neuroanatomical variations particular to the autism group), used the MRI data to create three-dimensional computer maps of each subject's brain, and then fed the values of five different measurements taken at each vertex of the computer model (which is made of tiny triangular facets meant to approximate the brain's curved surfaces) into a statistical-analysis algorithm called a Support Vector Machine, which Neuroskeptic describes much better than I could in this post.

The five things they measured at each vertex of their virtual mock-brains are as follows: average convexity/concavity of the cortical surface (i.e., the distance between the cortical surface at a given vertex and where the cortical surface would be if the brain were smooth); cortical thickness; mean (radial) curvature (i.e., the radius of the circle that could be drawn underneath the curve of the cortical surface); metric distortion or Jacobian, which is the ratio of the areas of the triangular facets making up the cortical surface and the gray/white matter interface; and the pial area, which is the average area of the triangular facets touching each vertex.

Since some of these things are very hard to visualize, here's a diagram:
Figure 1, in Ecker et al. (2010)

Overall, this five-parameter model works pretty well at predicting who is autistic** and who isn't, though I was surprised to see how much its accuracy differed from one side of the brain to the other. On all measures, there's a huge gap --- a gap of 20 percentage points or more, in all but one instance --- between the two brain hemispheres in terms of a given measure's accuracy (i.e., its ability to sort all subjects into the correct category), sensitivity (ability to correctly identify autistic subjects --- i.e., having a high number of true positives and a low number of false negatives) and specificity (ability to correctly identify non-autistic subjects --- i.e., having a high number of true negatives and a low number of false positives).

For whatever reason, the left hemisphere much more than the right showed consistent neuroanatomical differences between autistic and non-autistic subjects.

Here's a classification plot showing the two categories as determined by applying the five-variable classifier to the left hemisphere:
Here, all but two autistic subjects are placed into the positive (i.e., autistic) category, and all but four control subjects are correctly placed into the negative category.

Contrast that with the right-brain results ---

--- where you see a lot more crossover between categories, plus several subjects straddling the border line. It is also only in the left hemisphere that any correlation is observed between how far to the right of the dividing line a person is and their ADI scores in the social and communication domains.

Some parameters also performed better than others: cortical thickness had the highest accuracy levels of any parameter (90% in the left hemisphere!), followed by metric distortion.

Finally, in the left hemisphere the model also succeeded in distinguishing ADHD subjects from autistic ones. (In the right hemisphere, it placed about equal numbers of ADHD subjects in each category). That's important because it shows that the model is actually picking up on characteristics of autistic brains, instead of just registering all deviance from "normal."

So, what *ARE* these characteristics of autistic brains? Well, they vary by region --- not only in terms of which parameter is relevant, but also in terms of how autistic people differ from neurotypicals on a given parameter.

For instance, if you look at this map of how the autistic subjects' brains differed from the controls in terms of cortical thickness, you can see that some parts of the brain (mostly on the temporal lobe) tend to have a thicker layer of gray matter in autistic people, while in other areas (mostly on the frontal and parietal lobes), the cortex tends to be thinner in autistic people.

Figure 4 (A), in Ecker et al. (2010); red areas represent more gray matter in relation to average non-autistic brain, blue areas represent less gray matter.

Some of the areas that showed up as having an "excess" of gray matter surprised me, as differential activity in those areas (fusiform gyrus, superior temporal sulcus) had previously been theorized to underlie autistic "deficits" in making sense of faces.

Besides these differences in amount of gray matter, there were also some strong differences in gray matter geometry: first, the autistic subjects showed greater sulcal depth in two regions --- the intraparietal sulcus and the superior frontal cortex --- and second, the inferior parietal lobes and certain regions in the right frontal lobe --- the right supramarginal gyrus, postcentral gyrus, and orbitofrontal cortex --- along with the precuneus, showed different patterns of cortical folding.

For example, here's the right intraparietal sulcus:

From Figure 5 (B), in Ecker et al. (2010)

The blue line represents the cortical surface for the average control subject; the red line represents the average autistic subject's cortex. You can see that the sulcus goes down deeper in the autistic subjects, and also that the gyri on either side are a bit steeper.

I would like to point out, again, that it's not necessarily any single variation at any one region of the brain that this statistical analysis has tied to autism, though --- it's a pattern of gray-matter distribution. It's also a pattern that's so far only been observed in a tiny, rather homogeneous sample of autistic men --- much larger, broader-based studies of this classifier need to be done to see if the same patterns hold up for all of the people currently lumped together under the category "autistic," or whether separate neuroanatomical phenotypes will define autistic subtypes.

I would also like to see future studies done using different diagnostic tools to define the autistic group --- if the goal of this research is to establish a biomarker for autism diagnosis so that we can finally be done with frustratingly ambiguous diagnosing-from-behavior, it will hardly do to have the biomarker be dependent on one of the older behavioral diagnostic tools for its template!

*According to this table showing demographic data on the autistic and control (but not the ADHD) subjects, the autistic subjects were mostly young, and some middle-aged, men (the average age (33) was much closer to the age of the youngest person (20) than it was to that of the oldest person (69)) and had a very wide range of IQ scores as measured by the Weschler Abbreviated Scale of Intelligence. The standard deviation, for full-scale IQ and for verbal and performance IQ, was around 20 points for the autistic group, and scores ranged from 76 (just one point over the cutoff point the authors chose to designate intellectual disability, which is a full-scale IQ of 75) to 141, with verbal IQs ranging from 78 to 133 and performance IQs from 77 to 138. These subjects, I'd like to point out in the spirit of adding to Michelle Dawson's recent post on functioning levels, were all defined as having Asperger's or high-functioning autism.

**Autistic subjects were determined to be such using either the ADI-R (for fifteen subjects), the ADOS (for five) or both (two).

Ecker C, Marquand A, Mourão-Miranda J, Johnston P, Daly EM, Brammer MJ, Maltezos S, Murphy CM, Robertson D, Williams SC, & Murphy DG (2010). Describing the brain in autism in five dimensions--magnetic resonance imaging-assisted diagnosis of autism spectrum disorder using a multiparameter classification approach. The Journal of neuroscience : the official journal of the Society for Neuroscience, 30 (32), 10612-23 PMID: 20702694

Monday, September 13, 2010

Link Roundup: Fat Is a Feminist Issue Edition

Within the last week or so, there's been a spate of really good feminist blogging about intersections between feminism and fat acceptance.

From Feministe, three guest posts: one by Atheling, who blogs at This Wicked Day, about similarities between slut-shaming and fat-shaming; one by zuzu, who used to be a Feministe contributor and now writes mostly at her own blog, Kindly Póg Mo Thóin, that deals with how fat-shaming health alarmism actually harms fat people's health, both by keeping them out of doctors' offices and by leading doctors to look no further than their patients' BMIs to explain their various health problems; and one by Spilt Milk (who writes an eponymous blog) about how body-shaming permeates mother-daughter relationships and how fat acceptance is radical because it's based on kindness and, well, acceptance, first of yourself and then of others.

There's also this terrific post by Meowser at Fat Fu, which contrasts the reasonable things fat-acceptance advocates are actually saying with the raving denialism everyone else seems to hear:
We say, "Weight is, for the most part, not a very good proxy for health, and there are much better ones, like socioeconomic status." They hear, "Being dozens of pounds over (or under) your baseline weight is just ginchy for you, and your doctor should never bring it up ever." ...

We say, "What causes people to weigh what they do is complex and multifactorial, and varies a lot from one person to another - and you can't tell what people's habits are from their pants size." They hear, "Weight is purely inherited and has nothing whatsoever to do with behavior." ...
We say, "Hounding kids about their weight is not likely to result in happier or healthier kids OR adults, for the most part." They hear, "We don't care if all the children lose their toes to dry gangrene by the time they're 12, as long as we can eat all the baby-flavored donuts we want."
Finally, there's this post by Aunt B at Tiny Cat Pants. She talks about two important things that often go unacknowledged in discussions about fat, public health and how U.S. society has changed: first, the class aspects of sitting around waxing oracular about why Those People are so fat and what they must be doing wrong ...
... [W]e talk about obese people having no self-control or being too stupid to know what to put in their bodies or lacking access to experts who could tell them what to do with themselves; the narrative is all about how obese people put all kinds of things in their bodies because they're too stupid (or uneducated to know better) and they thus have really negative life outcomes. Now, read that same sentence and swap out "obese" for "poor."

It works just the same.

I find that interesting. In both cases, it's about a group that has too many people in it, who need education and expertise and guidance, and who are deemed failures or troublemakers if they resist efforts from the outside to improve them.

The word "class" doesn't quite fit, but I think it has to do with demanding people want to strive to remove evidence of what has been deemed their shitty circumstances. Yes, of course, you will be punished for striving. But you will be punished worse for not striving.

It's almost as if the obese/the poor, by their very existence, insult their "betters" by not recognizing and properly responding to their "betters'" expertise on how best to live life.
... and, later, about implicit sexism in how most people --- even most feminists --- talk about fat:
Is it really not clear to feminists how the "obesity epidemic" is about reasserting the right to police women's bodies? Except now, we're doing it for your health!When people talk wistfully about how "nobody cooks at home anymore" who do you think that "nobody" used to be? When people talk about how kids don't get the same free rein of the neighborhoods they used to have, who is the unspoken monitor of all that free time?

Who has, supposedly, fallen down on the job causing us all to be fat?
Spilt Milk also addresses the mother-blaming aspect of obesity panic in her post --- she describes the double bind mothers find themselves in where, if a daughter develops an eating disorder, it's the mother's fault for being too uptight about food and teaching the daughter to hate her body, while, at the same time, if the children are fat, the mother is blamed for being too lazy to cook healthy food and make sure her children get enough exercise!

EDIT: Radical feminist blogger The Bearded Lady has also written two recent posts on fat acceptance: one --- like zuzu's that I linked earlier --- about fat women and doctors, and how doctors both miss underlying conditions that need treatment because they think fat people just need to lose weight, and also how doctors will see a fat woman's fatness as so dangerous, so unhealthy, that they will prescribe extremely aggressive measures to get them to lose weight. Her other entry is about her personal journey toward fat acceptance, and how for her, accepting her body came as part of her radical feminism, and her rejection of heterosexuality:
[A]lthough I had previously strenuously denied any connection between hating my body and wanting men to like me, when I stopped wanting men to like me, I stopped hating my body. Not immediately, in a flash of insight, but gradually, over time, I realised that I was looking at myself in the mirror and not thinking 'ugly' -- not thinking anything at all, really, just looking for toothpaste on my chin or whatever.

Hating my body/self was, for me, expressed not only in extreme dieting and thinking myself deeply ugly, inside and out. I also hated my body by allowing men to use it, by letting men fuck me, when I (the tiny little voice inside me that was barely allowed to speak) knew that I was being violated and used. It was a joyful moment when I realised I could just stop.
I especially liked that entry of hers, because it's probably the closest any other woman has come to describing a relationship to her body, and to the concept of "attractiveness" and whether one possesses it or not, that resembles mine. It's not a total match, and some things are actually very different between the two of us --- I never went through a period of intense dieting and *wanting* to be thin and conventionally attractive like she did, for instance --- the end state she describes is very close to what I have, and it entails a rejection of beauty and attractiveness rather than the reclamation of those things that seems to be a lot more common for large women who learn to love their bodies. I might write more about how that came about for me later, but for now I was just really happy to see someone else articulate these feelings that I also have, and have struggled to characterize accurately.

Saturday, September 4, 2010

Neither This Blog Nor My Etsy Store Is Dead ...

... and what better way to demonstrate those two facts than by posting pictures of my latest offering?
One reason I haven't been posting, reading or commenting as much on blogs is because I've been having a glut of ideas for jewelry pieces, and thus have been spending a lot of time making them.
Most of them are sitting around in a half-finished state, as problems arise and have to be troubleshot, worked around or --- sometimes --- the piece in question needs to be started over altogether.
(Problems usually take the form of too many loose ends not staying hidden, too many unsightly knots or awkward bulges, or a bead unexpectedly shattering as I try to force too many strands of thread through it.)

But I have two new projects that *are* totally done, and here's one of them!
As I might have mentioned before, I love geometric shapes. I also love contrasting colors.
This panel bracelet manages to tie both of those things I think are awesome together, with its framed boxes in alternating canary yellow and ... whatever you call a light blue that has a (very slight) hint of teal or turquoise in it. Each of those panels is made of twelve rows of twelve seed beads, all woven together with peyote stitch. (The beads are wider than they are long, so a 12 x 12 matrix ends up being a rectangle, not a square).
Another thing I love --- on bracelets, at least; on necklaces they tend not to stay fastened --- is a button or toggle clasp. Much easier to open or close than those thumb-operated ones with the tiny levers that require you either to have long fingernails (nope) or to never, ever lose your grip (also nope) in order to open them one-handed. Lately, just about everything I make has a button clasp, but I did get a set of toggle clasps recently that I decided to use making these:
(That's my arm --- big, hairy, and stylish!)
I made three of these; two to sell/wear myself until they are sold, and one I gave as a gift.
I really like this motif of the rectangular panels with geometric designs on them strung together on a sort of cuff. I think it's one of the more original design templates I've come up with, and I'm definitely doing a lot more with it.