Draulans Sylvia
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Autism as the result of an extreme male brain
Autism as the result of an extreme imprinted
brain
Autism as the result of a reptile brain
Autism as the result of epistatic interactions
between the effects of genes
The Theory of Mind Hypothesis of autism
Weak Central Coherence theory
The broken mirror theory
affected individuals are extremely focused on systemizing
>< empathizing
Men: more systemizing brain
Women: empathizing brain
Support for the theory:
1) more males are affected by autism
2) high-functioning affected individuals tend to outperform
unaffected people with similar IQs on systemizing tasks
3) behavioral differences between people with and without
autism are mediated by differences at the anatomical
level of the brain.
4) prenatal exposure to testosterone (an androgen) is
positively related to the development of autistic traits.
(Ploeger & Galis, 2011)
condition which we strongly associate with
autism
may have had practical advantages given
demands of ancestral times
These advantages would have conferred
greater reproductive success
(Ploeger & Galis, 2011)
imbalanced genomic imprinting theory
Genomic imprinting: expression of genes
from only one of the two parental
chromosomes.
We inherit two copies of every allele, a
maternal and a paternal copy.
In most cases both copies are functional
in some exceptional cases one of the copies
is turned off and thus not functional.
(Ploeger & Galis, 2011)
maternal imprinting ensures that only the
maternal copy is expressed
paternal imprinting ensures that only the
paternal copy is expressed.
evolutionary function of imprinted genes is
unknown
(Ploeger & Galis, 2011)
genomic imprinting originates in a conflict
between the sexes about the amount of investment of the
mother in the child.
Paternally expressed imprinted genes tend to promote fetal
growth
>< maternally expressed imprinted genes tend to suppress
fetal growth
father's point of view: beneficial that the mother invests as
much as possible in the child
mother's point of view: important to preserve her resources
imprinted genes are highly expressive in the central nervous
system
they are involved in neurodevelopment
Imprinted genes are often implicated in disorders, because a
single change can dysregulate their function
(Ploeger & Galis, 2011)
hypothesized that autism reflects reduced
maternal brain functions, and enhanced paternal
brain functions.
more males are affected than females.
children with autism impose additional demands
compared to normal children
which is beneficial from the point of view of the
father, because the mother will spend more of
her time and resources on the child
in the case of autism, the behavior of the child
assumes pathological proportions which no
longer benefit either the mother or the father.
(Ploeger & Galis, 2011)
Polyvagal theory
through stages of phylogeny, mammals, have evolved a
functional neural organization that regulates emotions and
social behavior.
humans have a well-developed ability to shift adaptively
between mobilization and social engagement behaviors
individuals with autism lack this ability
nervous system of the autistic individual is in a constant
state of hypervigilance or shutdown.
generally adaptive responses in reptiles, but are severely
maladaptive in mammals.
does not explain the genetic background and the
heritability of autism
(Ploeger & Galis, 2011)
Epistatic: interaction in which one gene suppresses
the expression of another
integration of different approaches on the evolution
of autism: interactions between the effects of genes
autism is caused by many interacting genes (nearly
30 genes)
this same set of genes is involved in the development
of intelligence.
intelligence is positively correlated with potential
reproductive success
30 genes that are involved in autism can potentially
spread in the population, thanks to the link with
intelligence.
(Ploeger & Galis, 2011)
some unlucky interactions, especially in combination
with negative spontaneous mutations
lead to the development of autism, low intelligence,
or other pathologies.
On certain intelligence tests, individuals with autism
show equal or better performance levels compared to
normal individuals.
evidence for the relation between autism and
exceptional abilities, with some famous examples of
autistic savants.
co-occurrence of savant syndrome and autism is an
example of the effect of epistatic interactions
between genes
(Ploeger & Galis, 2011)
combination of high heritability and low
fertility in autism
can be explained by the effects of epistatic
interactions
between genes that are involved in both
intelligence and autism.
(Ploeger & Galis, 2011)
refers to the ability to infer the full range of mental states
that cause action.
Possessing a theory of mind is to be able to effectively
reflect on the contents of one's own and others minds
allows us to predict and anticipate behaviors in others
and respond accordingly and appropriately.
Difficulty in understanding other minds and interpreting
behavior is a core cognitive feature of individuals
diagnosed with autism.
individuals with autism fail to “impute mental states to
themselves and others”
this deficit manifests as inability to mentalise, or failure to
take into account others’ mental states.
(Rajendran & Mitchell 2007)
transfer test of false belief
the participant watches a sequence of events
usually enacted by dolls
story unfolds so that one doll has a belief about the
location of an object that is incongruous with its real
location
participant then makes a judgment about where the
doll will look
in order to give the correct answer the participant has
to infer the mental state of the doll (I think he thinks)
80%of children with autism failed the unexpected
transfer task
(Rajendran & Mitchell 2007)
Problem: 20% of autistic individuals passed
tests of false belief
deficit seemed not to be universals
So they used the more difficult second-order
false belief task
(I think, he thinks, she thinks)
none of the children with autism passed the
test.
(Rajendran & Mitchell 2007)
remarkably successful in making specific
predictions about the impairments
in socialization, imagination and
communication shown by people with autism.
It cannot explain either the non-triad features
of autism, or earlier experimental findings of
abnormal assets and deficits on non-social
tasks.
it may be necessary to postulate an additional
cognitive abnormality
(Rajendran & Mitchell 2007)
it explains some of the non-social, as well as the
social features of autism
such as the attention to acute detail that ranges from
pedantry to obsession.
typically developing individuals process information
by extracting overall meaning or gist.
autism is characterized by weak or absent drive for
global coherence
individuals with autism process things in a detail,
focused or piecemeal way
processing the constituent parts, rather than the
global whole.
(Frith & Happé, 1994)
caused by a hypoactivity of mirror neurons
a neuronal system that is activated when an action is
performed by a person
and when the subject observes the same action done by a
conspecific.
one of the key mechanisms for what concerns social
interactions
it allows an individual to embody in himself the mental
states of those who have faced as they were their own.
Autistic patients would not be able to embody in
themselves others' mental states
due to a dysfunction related to mirror neurons.
hypoactivity of the mirror system would be found only in
certain circumstances and not in other.
(Keller & Bugiani & Fantin & Pirfo 2011)
imitation tasks which do notdo notdo notdo not require an explicit
imitative behavior: hypoactivity of the autistic mirror
system.
does not occur when the subject is explicitly asked to
imitate an observed movement.
deficits associated with the mirror system does not
stop at simple task imitation.
Autistic subjects have great difficulty in
understanding the others' intentions
seem to have no impairment regarding the goal of
the action, or rather the "what" of the action.
could not understand the general intention of the
model: "why" this action is performed.
(Keller et al. 2011)
Autistic subjects, for those problems of
embodiment of the mental states of others,
which are possible only thanks to mirror
neurons
have many difficulties in reading the
emotional states of others.
(Keller et al. 2011)
Ploeger, A., Galis, F. (2011). Evolutionary approaches to autisman
overview and integration. McGill Journal of Medicine : MJM,
13(2)
Rajendran, G., Mitchell, P. (2007). Cognitive theories of autism.
Developmental Review, 27 (2), 224–260.
Frith, U., Francesca Happé, F., Autism: beyond “theory of mind”....
MRC Cognitive Development Unit, 4 Taviton Street, London
Hwu, L., A., (2013). Dissertation Abstracts International: Section
B: The Sciences and Engineering, 74(3)
Weak Central Coherence Theory (WCC, Frith, 1989, Frith,
2003, Frith and Happé, 1994 and Happé, 1999) Developmental
Review Volume 27, Issue 2, June 2007, Pages 224–260
Keller, R, Bugiani, S, Fantin, P & Pirfo, E. (2011). Mirror neurons
and autism. Giornale Italiano di Psicopatologia / Italian Journal of
Psychopathology, 17(4), 404-412.