Research from the Yale University Child Study Center provides further evidence that autistic children view the world in markedly different ways than their non autistic peers. They were specifically looking at differences in attention to biological movement. According to the announcement by the National Institute of Health, who helped fund the study:
The researchers borrowed a technique from the video game industry, called motion capture. They then reduced the movements to only points of light at each joint in the body, like animated constellations. These cartoons played normally — upright and forward — on one half of the screen, but upside-down and in reverse on the other half. The inverted presentation engages different brain circuits and is known to disrupt perception of biological motion in young children. The normal soundtrack of the actor’s voice, recorded when the animations were made, accompanied the presentations.
You can view some of these animations in the New Scientist report on line
Yale recruited a sample of autistic toddlers and two control groups - normally developing toddlers matched for age and non-verbal intelligence and developmentally delayed toddlers matched for age and verbal intelligence. Then they showed them the animations and measured their attention to the biological and non biological animations.
Virginia Hughes, writing for the Simons Foundation Autism Research Initiative, tell us that
the toddlers with autism showed no preference for the upright figure when watching the peek-a-boo animations, looking at it 50.7 percent of the time, compared with 58.9 percent of the time for the developmentally delayed group and 62.7 percent for typical controls.
When watching the pat-a-cake animations, however, the autism group looked at the upright figure 65.9 percent of the time, significantly more than at the inverted figure. The pattern for the two control groups remained the same.
Not surprisingly non-autistic children showed a preference for cartoons played normally. Autistic children seemed not to have a preference, except for the pat-a-cake animation. The study team realized that this was because the movement of the dots of light synchronized with the clapping sound in the sound track. So they looked for less obvious audiovisual synchronies (AVS) in the other four animations. The AVS was less powerful in these other four animations than in the pat-a-cake example but still they found
“Audio-visual synchronies accounted for about 90 percent of the preferred viewing patterns of toddlers with ASD and none of unaffected toddlers,” said Jones. “Typically-developing children focused instead on the most socially relevant information.”
To test if the autistic toddlers were attending to AVS in preference to biological movement they recruited a fresh set of autistic toddlers and devised two more animations whose AVS was stronger than the unintended AVS in the four animations but less than the powerful AVS of the pat-a-cake animaton. If autistic attention was related to the strength of AVS they should be able to predict the new cohort’s preferred viewing patterns. And they did.
The study provides strong evidence that autistic toddlers do not have a preference for biological movement but are drawn to AVS that are ignored by non autistic peers and are not immediately apparent to research scientists without the assistance of computer analysis. This is potentially both a benefit and a deficit. Elizabeth Moon has written a novel, The Speed of Dark, about autistic adults whose ability to detect patterns and synchronies was valued while their need for accommodations in order to exercise this ability was decried. The novel’s strength derives in part from the author’s ability to exploit the dramatic tension between these two conflicting positions.
In contrast the present study does not even begin to acknowledge the potential strengths of this talent for detecting synchronies. Instead it focuses entirely on the negative aspects. The authors suggest that because attention to biological movement is such a robust feature, occurring across species and persisting in humans who are blind or cognitively impaired, its apparent absence in autism is enough to explain all the familiar impairments.
The authors explain it thus
Typically developing human infants preferentially attend to biological motion within the first days of life1. This ability is highly conserved across species2, 3 and is believed to be critical for filial attachment and for detection of predators4. The neural underpinnings of biological motion perception are overlapping with brain regions involved in perception of basic social signals such as facial expression and gaze direction5, and preferential attention to biological motion is seen as a precursor to the capacity for attributing intentions to others6.
There is a problem here. Klin et al argue that autistic subjects do not exhibit preferential attention to biological motion. Then they up the stakes dramatically with their reference to the ability to attend to biological motion. Ability and preference are not the same thing. Then comes another giant leap, suggesting that because of neural overlap with brain areas associated with facial expression and gaze direction, a preference for biological motion is somehow responsible for theory of mind.
So, rather than being an ability, enhanced awareness of audio-visual synchronies is a disability because it comes at the expense of attending to biological motion, which is believed to be critical for bonding with a caregiver, recognizing danger , developing social cognition and acquiring theory of mind. It may be that Klin et al are right and this skill is critical. But it is a bit of a leap to suggest that this is what their experiment tested for and that it is lacking in autistic children. If it is so highly conserved across species, the fact that it is not evident in autistic subjects in this experiment suggests not that it is absent or weak, rather that it is being overridden by higher brain functions. If it is so basic to survival that snails have it, its lack should present as a catastrophic deficit in humans. It would be interesting to devise an experiment to discover in what circumstances autistic children (and adults for that matter) do exercise a preference for biological movement. If it is so important we should be looking for ways to encourage it that do not diminish the achievements of autistic children in attending to patterns and synchronies in their environment.
Klin’s research is valuable. It is a pity that the commentary on the results overstated its importance and sought to overplay the potential disabling effects for autistic people while failing to acknowledge any potential strengths that might derive from synchronous thinking. Research that adds to our understanding should not need to be dramatized in this way.
Footnote
Morton Ann Gernsbacher has written some trenchant pieces about how preconceptions can influence the interpretation of research results. For example
Using the Deese-Roediger-McDermott “false memory” paradigm, two groups of participants were presented auditorily with lists of semantically related words (e.g., bed, rest, awake, tired, and dream), and later asked to discriminate between words they’d heard and words they hadn’t heard, including words that were semantically associated to words they’d heard (e.g., sleep). As shown in Figure 2, the green group demonstrated significantly better memory discrimination than the purple group; the green group was less likely to falsely recognize words they hadn’t heard, despite the false words’ semantic association with words they’d heard.
The green group’s better memory discrimination was attributed to their mentally representing words “in an aberrant manner,” even though a concurrent — and direct — test of semantic clustering found no differences between the green and purple groups. The green group’s aberrant semantic mental representations was hypothesized to stem from “anatomic abnormalities … or as a result of an as-yet unknown pathology.”
When another research team reported no difference between green- and purple-type participants in either false recall or false recognition, the authors of the study that had observed the green group’s better discrimination interpreted the other study’s lack of a between-group difference to the green group also having “frontal-executive impairment.”
No prizes for guessing that the green group were autistic. In another article she points out that if you are autistic:
having a thicker cortex than someone who is not autistic is considered bad (Hardan et al., 2006) — and having a thinner cortex than someone who is not autistic is also considered bad (Chung et al., 2005; Hadjikhani et al., 2006a, 2006b). Your thicker cortex might be a function of higher fluid intelligence (Dawson et al., 2006; Fjell et al., 2006); your thinner cortex might be a function of better memory retrieval (Sowell et al., 2001). It doesn’t matter: If you’re autistic, having either a thicker or thinner cortex is just considered bad.
May 12th, 2009
Posted by
Mike |
neuroscience, research |
23 comments
Brains that go bump in the night.
Brain science has come a long way in the last 200 years. We look back at the early efforts of the phrenologists to map personality, behaviour and mental abilities onto specific organs of the brain with amusement. But that is only because their methodology was so woefully inadequate. These brain organs were supposed to affect the contours of the skull and a skilled phrenologist would take measurements of the skull and use his clinical judgement to interpret them in order to draw conclusions about a person’s character or mental capacities.
The early phrenologists relied upon post mortem studies of the brains and skulls of criminals and the insane. They were looking for things like the theft organ or the murder organ. Later the focus shifted to more generalized concepts, seeking organs for greed, jealousy, benevolence or self esteem.
Modern brain imaging techniques enable today’s neuroscientists to see the brain in action in living subjects. They have given us a detailed anatomical map of the brain and have been able to succesfully map particular functions to specific areas of the brain. Their results provide a more reliable guide to the workings of the human brain than the phrenologists ever could.
It is important to remember that, despite having access to so much more accurate data about the brain than the phrenologists ever had, we have not moved on that far in our ability to interpret the data. We are still ruled by the belief that specific parts of the brain are responsible for different types of behaviour. Sometimes this belief is well founded. Language areas, motor areas, the visual cortex; all have been reliably mapped.
Just as every sin contains the seed of its own salvation, so every virtue contains the seed of its own corruption. Success in mapping so many functions onto specific areas of the brain has reinforced the belief that the determinants of all human behaviour can be located within specified areas of the brain. This takes us back beyond phrenology to Descartes and the dichotomy between body and soul. Just like phrenology, the Cartesian dualism of body and soul is another idea that has persisted beyond its time. Only now it refers to the biological determinism of the brain ruling the body; rather than the spirit being superior to the body.
Descartes also knew a thing or two that appear to have eluded modern reductionists in science. He did not regard the brain as the arbiter of all human behaviour. Bodily passions could overrule the brain and lead us into irrational behaviour as well. This particular model of human behaviour as a struggle between higher mental function and lower animal instincts is no longer given scientific credence, though it persists in theology and some forms of Freudian psychiatry. But the principle that biofeedback mechanisms within ourselves as well as external pressures can act to modify behaviour is a necessary corrective to the belief that biological determinism begins and ends in our genes.
If we are a product of our brains, our brains are a product of our DNA. There is a multi-million dollar research programme to discover the genes that cause autism. Strictly speaking, the genes do not cause autism. Researchers are looking for mutations in the genes that code for the proteins that build the parts of the brain that control the behaviours that are supposed to be impaired in autistic people. But in the popular consciousness we have already had attempts to discover the Gay gene, the gene for aggression, etc. Media coverage of genes and autism will inevitably reinforce the popular belief that genes code for behaviour.
Autism Under the Gyruscope
Never mind. The scientists know what they are looking for, don’t they? Well sort of. At one time scientists believed they had identified a part of the brain that plays a crucial role in face recognition. Attending to and remembering faces is a problem for many autistics. It is also a problem for me. So I have been following this research with some interest.
In 2001 Karen Pierce et al. published a paper, Face processing occurs outside the fusiform `face area’ in autism: evidence from functional MRI, that showed that unlike non-autistic controls,
Overall results revealed either abnormally weak or no activation in FG [fusiform gyrus] in autistic patients, as well as significantly reduced activation in the inferior occipital gyrus, superior temporal sulcus and amygdala.
Again, quoting from the abstract,
Such a pattern of individual-specific, scattered activation seen in autistic patients in contrast to the highly consistent FG activation seen in normals, suggests that experiential factors do indeed play a role in the normal development of the FFA. [fusiform facial area]
The argument seems to be that autistic children spend less time looking at faces than normal children. So their FFA is impaired from under use. At the time this made perfect sense to me and encouraged me in my practise of teaching eye contact and facial recognition to my autistic pupils. But according to Pierce the autistic adults in her study where just as good at the task as the control group. The abnormality was in the brain areas they used to perform the task. These adults had obviously trained themselves in facial processing. So why hadn’t their FFA kicked in when they did take an interest in faces?
This suggests that autistic brains have impaired or different wiring. But it does not explain why. The picture was further complicated when Geraldine Dawson reported that children took time to develop their fusiform gyrus but it was normally fully functional by age 12. Perhaps there is a window of opportunity when the FFA can be activated but once this has passed other pathways have to be utilized.
She showed pictures of cars and faces to 11 autistic adolescents and adults and to 10 age matched controls. In all of them the temporal inferior gyrus reacted normally, activating in response to the cars. It also activated in response to the faces in the autistic subjects. There was one anomaly. Autistic subjects did use their fusiform gyrus when looking at pictures of their mothers. I wrote at the time,
This suggests to me that (contrary to the popular belief that autistic aloofness arises from the fact that their brains are differently wired) intense emotional experiences may help to shape brain function. ACs have brains that can work in exactly the same way as their NT counterparts. The fact that they do not respond to everybody in the same way just goes to show that their brains are just far more discriminating in the range of stimuli and experience that shape their response. As ever with autism, the actual mechanisms are far more subtle than we first imagined.
I had no idea what I was talking about! I see echoes of Victor and Dr Itard in those “intense emotional experiences.” there are also dubious echoes of holding therapy, a misguided and dangerous attempt to force an emotional bond with the mother where none was presumed to exist. The truth is I could not explain the anomaly and was rather clumsily using it to make the point that we are a long way from fully understanding autism.
Rectifying the Anomaly
The one good thing about science is that scientists love an anomaly. If something blows a hole in the current theory, a good scientist will find it interesting and follow it up. As it happens I was not too wide of the mark with my guess that,
their brains are just far more discriminating in the range of stimuli and experience that shape their response.
What if the fusiform gyrus is not an area for processing faces? What if everybody’s brains are more discriminating than we imagined? In this paper the fusiform gyrus and the inferior gyrus are both implicated in an expert object recognition pathway.
ABSTRACT
Brain imaging studies suggest that expert object recognition is a distinct visual skill, implemented by a dedicated anatomic pathway. Like all visual pathways, the expert recognition pathway begins with the early visual system (retina, LGN/SC, striate cortex). It is defined, however, by subsequent diffuse activation in the lateral occipital cortex (LOC), and sharp foci of activation in the fusiform gyrus and right inferior frontal gyrus. This pathway recognizes familiar objects from familiar viewpoints under familiar illumination. Significantly, it identifies objects at both the categorical and instance (subcategorical) levels, and these processes cannot be disassociated. This paper presents a four-stage functional model of the expert object recognition pathway, where each stage models one area of anatomic activation. It implements this model in an end-to-end computer vision system, and tests it on real images to provide feedback for the cognitive science and computer vision communities.
Expert object recognition? Perhaps the Fusiform Gyrus reacts to faces because most of us have an interest in faces and become quite expert at recognizing them. What if we became expert in something else. Would that light up the fusiform gyrus? Isabel Gauthier et al tested this by creating a set of novel objects called greebles and training volunteers to become greeble experts.
She concludes
The strongest interpretation suggested by our results together with previous work is that the face-selective area in the middle fusiform gyrus may be most appropriately described as a general substrate for subordinate-level discrimination that can be fine-tuned by experience with any object category.
One of Gauthier’s collaborators, Michael Tarr, has reported on similar research with extant experts and, just as with the Greebles, the fusiform gyrus is involved
Several of our findings speak directly to the question “Are faces special?” First, Greeble experts, but not Greeble novices, show behavioral effects – notably configural processing – that are often taken as markers for specialized face processing (Gauthier & Tarr, 1997; Gauthier et al., 1998). Second, Greeble experts, but not Greeble novices, show category-selectivity for Greebles in the right fusiform gyrus (Gauthier et al., 1999). Similarly, bird experts show category-selectivity for birds, but not cars, in the right fusiform, while car experts show category-selectivity for cars, but not birds (Gauthier et al., 2000). Reinforcing the generality of this result, chess experts, but not chess novices, likewise show category-selectivity in right fusiform for valid, but not invalid, chess game boards (Righi & Tarr, 2004). Third, across Greeble expertise training, subjects show a significant positive correlation between a behavioral measure of holistic processing (sensitivity to the presence of the correct parts for that object) and neural activity in the right fusiform (Gauthier & Tarr, 2002). Similarly, bird and car experts show a significant correlation between their relative expertise measured behaviorally (birds minus cars) and neural activity in the right fusiform (Gauthier et al., 2000). Behaviorally measured chess playing ability also shows a significant correlation with right fusiform response (Righi & Tarr, 2004). Fourth, the N170 potential (as measured by event-related potentials) shows face-like modulation in Greeble (Rossion et al., 2000), bird and dog experts (Tanaka & Curran, 2001), but only for a given expert’s domain of expertise.
So is the anomaly solved? Autistic children become experts on significant adults like mothers and thus arouse the fusiform gyrus when they see a picture of Mum. That still leaves open the question of why autistic children are not naturally interested in faces or social interaction to the same extent as their peers. Will the neuroscientists now go looking for the brain area that motivates us to become people experts? And when they find it how will they know it is the people area and not a different category of area that just motivates us to become experts?
It would be really nice if all those parents that yearn for some acknowledgement of affection from their autistic children could be shown an fMRI scan of their child’s fusiform gyrus lighting up when they walk in the room.
November 4th, 2007
Posted by
Mike |
Autism, genetic research, neuroscience, science |
14 comments
There are a number of stock phrases that appear in media reports on autism with annoying regularity, phrases like:
- autism epidemic;
- this devastating disorder;
- the fastest growing developmental disorder.
They annoy me because they express ideas about autism that are either disputed or unproven. But their constant repetition leads them to be accepted as statements of fact. There are no epidemiological studies that demonstrate the existence of an epidemic. Indeed, there are good reasons not to believe in an autism epidemic. It only appears to be growing so fast if you include all the “mildly affected” (another annoying phrase) people who would not have been diagnosed 25 years ago when autism was considered a narrow disorder rather than today’s broad syndrome.
And who is devastated by autism? Is it the parents or their autistic children? And why are they devastated? Could it be the lack of services or the exclusion clauses in their health insurance that put those services out of reach? Some of us are devastated by the time, effort and money expended on debunking myths about vaccine induced epidemics and their corollary, the efforts to counter environmental theories of causation by finding genetic causes for autism. We would prefer the money to be spent providing those services that have proven beneficial. For example
In cases of severe autism, for example, Attwood says: “When I started in the area 30 years ago, only 50 per cent acquired speech. Today, only 15 per cent don’t acquire speech.”
How many speech therapists could you buy with the £15 million of public money spent on the abortive anti-MMR litigation in the UK or the millions of dollars expended on the Omnibus autism proceedings in the USA? These proceedings are also on the brink of collapse unless the litigants can find three typical cases to come forward from the 4,500 at their disposal. Their prospects of success appear to be diminishing.
Californian politician Rick Rollens is a fervent advocate for the link between vaccines and autism. He is also responsible for one of the most annoying media catch-all phrases, “full syndrome autism.” He means autistic disorder. But “full syndrome autism” deliberately suggests “worst case autism.” Rollens invites us to take all the negative aspects of autism and imagine them in a single child. He goes on to suggest that the year on year increases in the autistic caseload of the California Department of Developmental Services (CDDS) represents an epidemic of this worst case autism that is devastating the lives of children.
Jonathon has provided a consistent critique of Rollens’ use and abuse of CDDS statistics. Autism Diva has cast light on his bullying tactics.
Autism Diva sat across a table from Rick Rollens last year as Rollens accused a reputable scientist of being on the take, because that scientist had written things that tended to discount Rollens’ (dead) pet hypothesis of THE EPIDEMIC OF AUTISM. The scientist in question was not in the room and so couldn’t defend him or herself.
Whether he is wilfully ignorant and rude or just plain stupid, Rollen’s invention of full syndrome autism is now part of the language. An additional annoyance for me is that his kind of misinformation and pandering to prejudice always seem to lend itself to simplistic language that registers in the popular imagination, while rational rebuttals and refutations of this sort of nonsense appear counter-intuitive and long-winded. To paraphrase William Booth, “Why should the devil have all the best slogans?”
So imagine my delight when I came across the slogan, Full Spectrum Resistance.
I really like the idea of countering “Full Syndrome Autism” with “Full Spectrum Resistance.” I found that slogan in a brochure for Marxism 2007, A Festival of Resistance. Marxism is an annual event in London that provides a platform for left wing thinkers and activists from round the world.
In the past Marxism has featured one of my favourite neuroscientists, Steven Rose. He will not be speaking this year. But his ideas about evolution, genes and human nature have had a persuasive influence on me. One of the few benefits of long distance air travel is that it gives you time to read. On a recent round trip to New Zealand I devoured two of Rose’s books, Lifelines and The 21st Century Brain. In Lifelines he argues against the overly deterministic theories encapsulated by Dawkin’s The Selfish Gene. His answer is to place the organism at the centre and explore the complexity of life. Genes play their part but do not determine the outcome. The subtitle Life Beyond Genes is an apposite summary of the book
The 21st Century Brain is equally good at tackling the reductionist tendencies in neuroscience and reasserting the conscious self as an active agent in the world against a vision which sees,
Human agency … reduced to an alphabet soup of As, Cs, Gs and Ts in sequences patterned by the selective force of evolution. whilst consciousness becomes some sort of dimmer switch controllng the flickering lights of neuronal activity. Humans are simply somewhat more complex thermostats fashioned out of carbon chemistry. [page 297]
This book is subtitled Explaining, Mending and Manipulating the Mind, which seems to summarize the aim of a lot of autism research. Unfortunately most of it follows the reductionist trend which Rose ascribes to the fact that many of those working in the biological sciences aspire to the mathematical precision and predictability of physics. He, on the other hand. positively revels in the “fuzzy way of thinking” or more formally the “epistomological pluralism ” that he deems essential if we are to embrace the complexities of life.
May 13th, 2007
Posted by
Mike |
Autism, language, marxism, neuroscience, science |
9 comments
