Sunday, May 17, 2009

Ferrari Hind-Brain, Dune Buggy Frontal Lobes

Fads in education tend to be oversimplified, and the newest of fads is no exception.
Think about this current catch-phrase in education for a moment: Brain-based learning.

People are writing curricula and textbooks and making a lot of money from this phrase.

Whenever I hear it in a seminar or discussion, I am always tempted to raise my hand and ask, "Isn't all learning brain based?" Because it is. At least the learning we are supposed to be talking about when we are talking about educating children in school.

The other one--and it's been around for a while now--is the whole left-brained vs. right-brained cliche. You know it: right-brained people are so much more enlightened and spiritual than those who dwell in the concrete-sequential left brain. Except . . . it appears the religious experience is partially mediated by the left temporal lobe. Sorry, wrong hemisphere.

There is some truth to the idea that there is a hemispheric division of duty in the brain. In males, language processing is normally in the left hemisphere, whereas certain associations of the images that language evokes take place in the right hemisphere. But females tend to distribute language processing across the two hemispheres, and since the female corpus collosum tends to be larger and denser and signals move across it more rapidly, why shouldn't they?

Guys, this may be why you cannnot win at verbal tete-a-tete with your mothers. But I digress . . .

Consider the paragraph above the digression about guys. The word "normally" is operative there. Because neuroplasticity is such that people do all kinds of things with parts of their brains normally reserved for something else. And there are those on the autism spectrum that make an art of it, experiencing synasthesia, the ability to smell color, for example, or hear shapes.

The semester's work that I just finished (thank Heaven and the PsychInfo data base) was about differences in sensory processing between people with Autism Spectrum Disorders (ASD), and typically developing individuals (NTs). I looked at visual processing, but I could have just as easily looked at other senses. In all of them it is the same. Autistics process differently, using different parts of the brain on both the right and left sides, because the real difference is between front and back.

Uta Frith, one of the researchers about this, says that non-autistics have a drive towards central coherence. NTs will look at the picture, and initially see the parts and then the whole, but they do it very quickly, and then prompty forget the details in that drive to the big picture. Many with ASD do not. Rather, their focus on the local processing is intense, and they remember the details and focus on them, sometimes not seeing the big picture at all. This makes them very good at the Block Design subtest on the Weschler Intelligence Scales (WISC or WAIS) and very bad at the Comprehesion portion.

And what portions of the brain light up on fMRI when these kids are doing tasks like BD? It appears that they shift their function backwards, to more local function. Some researcher think they mentally move shapes needed to match detail to the whole, rather than place the figure in working memory, like NTs do. The NT strategy for embedded figures and block design has many more top-down features, and thus on these kind of tasks, individuals on the spectrum are more efficient and work faster. And in time-constrained situations, they also tend to be more accurate.

These visual processing differences appear to be primary in nature, by which I mean that they show up on both social and non-social tasks. It is true that autistics process faces differently, with much of the activations happening outside the fusiform gyrus' face area. But in ASD samples, processing of right-side up and upside down faces is equally as fast, whereas in NTs it is not. This may mean that it is perception that is fundamentally different, and that it is possible that many of the other characteristics of autism flow from it, rather than from a fundamental difficulty with social interaction.

Some researchers believe that these perceptual differences are the root of savant skills like card-counting, calendar calculating, or perspective in drawing.

There are still arguments in the field about whether of not this "weak central coherence" is compensation for a deficit or whether it is an enhanced perceptual function in its own right. There is evidence that those with ASD do engage in top-down control (from the frontal lobes), and that the local perceptual functioning (bottom-up) is more efficient. But there is also evidence that the observed top-down processes are qualitively different than those in NTs.

But it is safe to say that perception in ASD (and to some extent in ADHD as well) is fundamentally different than in NTs.

fMRI activation maps do show difference across the hemispheres, but also from the back of the brain to the front. In autistic perception, the activated areas are more scattered throughout the brain, and different areas light up for perceptual tasks than in NTs.

All of this means that the structure of intelligence is different in ASD. On the new WISC and WAIS scales, the Working Memory and Processing Speed indices result in much lower scores than the norm, whereas the Perceptual Organization and Verbal Comprehension are much higher. This is true within the individual scores, so that any full-scale IQ score is essentially meaningliess. When fluid intelligence, which is the ability to reason abstractly, is measured alone, as it is on Ravens Progressive Matrices, scores are generally very high in high-functioning autism (HFA) and Asperger Syndrome (AS).

One problem with intelligence testing done by educators as opposed to those done by professional psychologists, is that they often calcuate a FSIQ when the gaps between subtests and indices are so wide as to make that number meaningless. This meaningless number is then used as a measure of a child's potential, and is attached to him/her, sometimes for years, and limits what the child is allowed to do in school. To add insult to this injury, schools are designed for the average (and with NCLB, the slightly below) child, and instruction is auditory-sequential in nature, which relies heavily on auditory working memory and processing speed. This is why school is a difficult place for a child on the spectrum to actually get an education.

The rules are made for NTs. Thus one has to memorize math facts before being allowed to take higher math. And one must take algebra before geometry. Neither of these Stupid Neurotypical Rules (SNTR: coined by Temple Grandin) make sense for kids who see the world through such different perceptual lenses. The should use a calculator. And take geometry first. And then use hands-on equations for algebra. Even so, the teacher must be able to teach math outside the SNTR box.

Here's the bottom line:

It's not about right- or left-brained people. But we could say that Aspies, Autistics, and ADHD's, all have Ferarri motors in the hind brain, but with a dune buggy control system in the frontal lobes, the drive for them is anything but smooth in the narrowly defined normal of the typical school.

1 comment:

christinemm said...

I knew you would share your opinion when you had the time and energy.

Thank you for sharing!