psy341 - TT2 artical readings.doc

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20 Apr 2012
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Constraining heterogeneity: the social brain and its development in autism spectrum disorder
- common brain-system level feature of autism: “developmental disconnection”
ofailure to develop normal connections between higher order association areas of
temporal and parietal cortices and regions of the frontal cortices
o“underconnectivity”
oAccounts for symptoms and heterogeneity
oFunctional connectivity decrease with age in children with ASD
oProminent effects on brain connectivity from experience of profound, early, and
severe socioemotional deprivation
oCause or effect of ASD?
- reciprocal relationship between brain disruption and atypical social development drives
homogeneity in ASD presentation even in enormous phenotypic and genotypic
heterogeneity
- proposed model: ASD beings with failure in emergence of specialized functions of one or
more of the set of neuroanatomical structures involved in social information processing
oalters neural connections
ochild not able to accept opportunities of social reciprocity, therefore impairs normal
cognitive development
o“The social brain” – complex network of areas that enable us to recognize other
individuals and to evaluate their mental states
- Right posterior STS selective processes biological motion
oactive when individual views human or robot walking, not when inanimate object
(i.e. grandfather clock)
- Right posterior STS is sensitive to prior emotional context
oexhibited more activity for incongruent trials (when emotion shown by actress does
not match her actions) than congruent trials (when emotion shown does match
actions)
oHOWEVER: posterior STS known to be involved in attentional shifting to visual
cues
Number of attentional shifts equal between congruent and incongruent
trials.
oExperiment repeated with ASD vs control groups
Control showed greater activity for incongruent > congruent
This NOT seen in ASD group
- ASD hypoactivation of the right FFG and bilateral amygdale
oCannot be reversed by manipulation of eye movement
oDisruption in directing eye movements to the key, most socially relevant features of
the face is the core feature in brain phenotype in autism
- showed control, ASD, and paranoid schizophrenic groups faces and asked to rate
trustworthiness or age
otrustworthiness, age, reaction time did not differ
oASD and paranoid schizophrenic groups significant reduction in right amygdale,
FFG, and left VLPFC/AL
oASD: no activation of posterior STS in trustworthiness test
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“neural signature” of ASD?
- abnormal posterior STS development abnormal social-cognitive development ASD?
- Positive correlation between magnitude of differentiation between biological and
nonbiological motion in the right posterior STS and age
oSpecialization of cortical network for perception of biological motion becomes
increasingly fine-tuned throughout development
Development of left occipitotemporal systems for skilled reading in children after a
phonologically-based intervention (see lecture notes)
- Standardized testing:
oWord Attack subset of WRAT—tests pseudowords
oVerbal intelligence of WISC—IQ
oGORT—rate, accuracy, frequency, comprehension
- Community vs Experimental Intervention (phonological-based) for a year
- Results:
oGORT higher in EI
oGreater left hemispheric activation in both treatment groups; greater in EI
Inferior frontal gyrus, parietotemporal, occipitotemporal regions
Perception and estimation of duration in long-term survivors of childhood posterior fossa tumors
- perception of duration: ability to discriminate intervals as more or less simultaneous or
judge events that take place in the psychological present with an upper limit of 5 s
obeyond and must be stored in STM—temporal judgment = estimation
oestimation and perception of duration differ in cognitive systems involved
- perception of duration involves cerebellum, basal ganglia, SCN
- estimation involves higher-order cognitive processes
oretrospective (duration that has already passed) vs. prospective (duration in future)
estimation
- used to test degree of representational complexity and abstraction
- cerebellar lesions and medulloblastomas—their effects on short-duration perception, long-
duration estimation, and spatiotemporal estimation
- experiment 1: short-duration perception
odiscriminating among intervals in 400 ms range
tumour group less able to discriminate among durations
did not differ in ability to discriminate frequence differences in the 3000 Hz
range
no relationship with IQ
older children did better
- experiment 2: long-duration estimation
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