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From early markers to neuro-developmental mechanisms of autism.

Gliga T, Jones EJ, Bedford R, Charman T, Johnson MH - Dev Rev (2014)

Bottom Line: A fast growing field, the study of infants at risk because of having an older sibling with autism (i.e. infant sibs) aims to identify the earliest signs of this disorder, which would allow for earlier diagnosis and intervention.Although autism is mainly seen as a disorder of social interaction and communication, emerging early markers do not exclusively reflect impairments of the "social brain".We discuss the implications infant sibs findings have for future work into the biology of autism and the development of interventions.

View Article: PubMed Central - PubMed

Affiliation: Centre for Brain and Cognitive Development, Birkbeck College, University of London, United Kingdom.

ABSTRACT
A fast growing field, the study of infants at risk because of having an older sibling with autism (i.e. infant sibs) aims to identify the earliest signs of this disorder, which would allow for earlier diagnosis and intervention. More importantly, we argue, these studies offer the opportunity to validate existing neuro-developmental models of autism against experimental evidence. Although autism is mainly seen as a disorder of social interaction and communication, emerging early markers do not exclusively reflect impairments of the "social brain". Evidence for atypical development of sensory and attentional systems highlight the need to move away from localized deficits to models suggesting brain-wide involvement in autism pathology. We discuss the implications infant sibs findings have for future work into the biology of autism and the development of interventions.

No MeSH data available.


Related in: MedlinePlus

Different mappings between behavioral and brain markers and clinical outcome. Clinical classification of high-risk infants is carried out around 3 years of age and results generally in three sub-groups: a group of children that have developed autism (Sib-A), a group that have typical developmental outcomes (Sib-T), and a group that show some atypicality, generally developmental delays or sub-clinical autism symptoms (Sib-Aty). (a) At 7 months Sib-A orient and maintain attention to faces just as all the other groups do (Elsabbagh, Gliga, et al., 2012) (b) The difference between event-related responses to “towards” and “away” gaze looks atypical in all high-risk groups, but only Sib-A are significantly different from Controls (Elsabbagh, Mercure, et al., 2012); (c) Latency to re-orient from a central fixation to a peripheral target is much shorter in Sib-A, but looks typical in the other high-risk groups (Elsabbagh, Fernandes, et al., 2013) (d) Sensory sensitivity is highest in Sib-A but lowest in Sib-T. This could reflect a protective effect of decreased neural noise in somatosensory cortices (Clifford et al., 2013). This complex mapping between markers and clinical outcomes suggests multiple interacting developmental pathways are involved in the emergence of autism symptomatology. Bars represent standard error.
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f0005: Different mappings between behavioral and brain markers and clinical outcome. Clinical classification of high-risk infants is carried out around 3 years of age and results generally in three sub-groups: a group of children that have developed autism (Sib-A), a group that have typical developmental outcomes (Sib-T), and a group that show some atypicality, generally developmental delays or sub-clinical autism symptoms (Sib-Aty). (a) At 7 months Sib-A orient and maintain attention to faces just as all the other groups do (Elsabbagh, Gliga, et al., 2012) (b) The difference between event-related responses to “towards” and “away” gaze looks atypical in all high-risk groups, but only Sib-A are significantly different from Controls (Elsabbagh, Mercure, et al., 2012); (c) Latency to re-orient from a central fixation to a peripheral target is much shorter in Sib-A, but looks typical in the other high-risk groups (Elsabbagh, Fernandes, et al., 2013) (d) Sensory sensitivity is highest in Sib-A but lowest in Sib-T. This could reflect a protective effect of decreased neural noise in somatosensory cortices (Clifford et al., 2013). This complex mapping between markers and clinical outcomes suggests multiple interacting developmental pathways are involved in the emergence of autism symptomatology. Bars represent standard error.

Mentions: There is substantial evidence that neural systems that bias attention towards human faces or eyes are functional from the first months of life in typical development (Farroni, Mansfield, Lai, & Johnson, 2003). These mechanisms are actually most useful very early on, when limited attentional abilities make it difficult to select relevant information to attend to. It was suggested that orienting to faces and eyes in infancy relies on both sub-cortical and cortical networks, although evidence for the involvement of particular neural substrates is only indirect (Johnson, 2005). Thus, infants only a few days old preferentially orient to a schematic depiction of an upright face over an inverted face and to a face with open eyes over a face with closed eyes (Farroni, Csibra, Simion, & Johnson, 2002). If disruptions of these systems are involved in the development of autism, atypicalities should be identifiable within the first six months of life in infants who later develop autism (henceforth Sib-A). Surprisingly though, in the first year of life Sib-A are indistinguishable from typically developing infants on a variety of measures of early social orienting. Unlike older children and adults with autism (Jones et al., 2008; Klin & Jones, 2008; Klin et al., 2002), 6–9-month-old Sib-A show typical scanning of faces including a typical preference for looking at the eyes (Elsabbagh, Bedford, et al., 2013). Spontaneous orienting and engagement with static faces is typical at both 6 and 12 months (Elsabbagh, Gliga, et al., 2012; Fig. 1a). In a recent, densely sampled study of infants at risk, Sib-A oriented to the eyes more than their typically developing peers at 2 months of age. However, looking to the eyes decreases subsequently and becomes significantly lower than in controls at 24 months of age (Jones & Klin, 2013). Typical orienting to faces and eyes is measured in 6-months old Sib-A during live interaction (Ozonoff et al., 2010; Young, Merin, Rogers, & Ozonoff, 2009), but a decrease in orienting becomes apparent from 12 months (Ozonoff et al., 2010). One recent eye-tracking study of 6-month old infants did find decreased proportional time spent watching an actress’s face, but also less time looking at the screen in general. Since the study did not examine looking to stimuli with non-social content (Chawarska, Macari, & Shic, 2013), these results could potentially reflect general difficulties with maintaining attention to the screen rather than decreased social attention (see later on, when we discuss attentional control in Sib-A).


From early markers to neuro-developmental mechanisms of autism.

Gliga T, Jones EJ, Bedford R, Charman T, Johnson MH - Dev Rev (2014)

Different mappings between behavioral and brain markers and clinical outcome. Clinical classification of high-risk infants is carried out around 3 years of age and results generally in three sub-groups: a group of children that have developed autism (Sib-A), a group that have typical developmental outcomes (Sib-T), and a group that show some atypicality, generally developmental delays or sub-clinical autism symptoms (Sib-Aty). (a) At 7 months Sib-A orient and maintain attention to faces just as all the other groups do (Elsabbagh, Gliga, et al., 2012) (b) The difference between event-related responses to “towards” and “away” gaze looks atypical in all high-risk groups, but only Sib-A are significantly different from Controls (Elsabbagh, Mercure, et al., 2012); (c) Latency to re-orient from a central fixation to a peripheral target is much shorter in Sib-A, but looks typical in the other high-risk groups (Elsabbagh, Fernandes, et al., 2013) (d) Sensory sensitivity is highest in Sib-A but lowest in Sib-T. This could reflect a protective effect of decreased neural noise in somatosensory cortices (Clifford et al., 2013). This complex mapping between markers and clinical outcomes suggests multiple interacting developmental pathways are involved in the emergence of autism symptomatology. Bars represent standard error.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4119302&req=5

f0005: Different mappings between behavioral and brain markers and clinical outcome. Clinical classification of high-risk infants is carried out around 3 years of age and results generally in three sub-groups: a group of children that have developed autism (Sib-A), a group that have typical developmental outcomes (Sib-T), and a group that show some atypicality, generally developmental delays or sub-clinical autism symptoms (Sib-Aty). (a) At 7 months Sib-A orient and maintain attention to faces just as all the other groups do (Elsabbagh, Gliga, et al., 2012) (b) The difference between event-related responses to “towards” and “away” gaze looks atypical in all high-risk groups, but only Sib-A are significantly different from Controls (Elsabbagh, Mercure, et al., 2012); (c) Latency to re-orient from a central fixation to a peripheral target is much shorter in Sib-A, but looks typical in the other high-risk groups (Elsabbagh, Fernandes, et al., 2013) (d) Sensory sensitivity is highest in Sib-A but lowest in Sib-T. This could reflect a protective effect of decreased neural noise in somatosensory cortices (Clifford et al., 2013). This complex mapping between markers and clinical outcomes suggests multiple interacting developmental pathways are involved in the emergence of autism symptomatology. Bars represent standard error.
Mentions: There is substantial evidence that neural systems that bias attention towards human faces or eyes are functional from the first months of life in typical development (Farroni, Mansfield, Lai, & Johnson, 2003). These mechanisms are actually most useful very early on, when limited attentional abilities make it difficult to select relevant information to attend to. It was suggested that orienting to faces and eyes in infancy relies on both sub-cortical and cortical networks, although evidence for the involvement of particular neural substrates is only indirect (Johnson, 2005). Thus, infants only a few days old preferentially orient to a schematic depiction of an upright face over an inverted face and to a face with open eyes over a face with closed eyes (Farroni, Csibra, Simion, & Johnson, 2002). If disruptions of these systems are involved in the development of autism, atypicalities should be identifiable within the first six months of life in infants who later develop autism (henceforth Sib-A). Surprisingly though, in the first year of life Sib-A are indistinguishable from typically developing infants on a variety of measures of early social orienting. Unlike older children and adults with autism (Jones et al., 2008; Klin & Jones, 2008; Klin et al., 2002), 6–9-month-old Sib-A show typical scanning of faces including a typical preference for looking at the eyes (Elsabbagh, Bedford, et al., 2013). Spontaneous orienting and engagement with static faces is typical at both 6 and 12 months (Elsabbagh, Gliga, et al., 2012; Fig. 1a). In a recent, densely sampled study of infants at risk, Sib-A oriented to the eyes more than their typically developing peers at 2 months of age. However, looking to the eyes decreases subsequently and becomes significantly lower than in controls at 24 months of age (Jones & Klin, 2013). Typical orienting to faces and eyes is measured in 6-months old Sib-A during live interaction (Ozonoff et al., 2010; Young, Merin, Rogers, & Ozonoff, 2009), but a decrease in orienting becomes apparent from 12 months (Ozonoff et al., 2010). One recent eye-tracking study of 6-month old infants did find decreased proportional time spent watching an actress’s face, but also less time looking at the screen in general. Since the study did not examine looking to stimuli with non-social content (Chawarska, Macari, & Shic, 2013), these results could potentially reflect general difficulties with maintaining attention to the screen rather than decreased social attention (see later on, when we discuss attentional control in Sib-A).

Bottom Line: A fast growing field, the study of infants at risk because of having an older sibling with autism (i.e. infant sibs) aims to identify the earliest signs of this disorder, which would allow for earlier diagnosis and intervention.Although autism is mainly seen as a disorder of social interaction and communication, emerging early markers do not exclusively reflect impairments of the "social brain".We discuss the implications infant sibs findings have for future work into the biology of autism and the development of interventions.

View Article: PubMed Central - PubMed

Affiliation: Centre for Brain and Cognitive Development, Birkbeck College, University of London, United Kingdom.

ABSTRACT
A fast growing field, the study of infants at risk because of having an older sibling with autism (i.e. infant sibs) aims to identify the earliest signs of this disorder, which would allow for earlier diagnosis and intervention. More importantly, we argue, these studies offer the opportunity to validate existing neuro-developmental models of autism against experimental evidence. Although autism is mainly seen as a disorder of social interaction and communication, emerging early markers do not exclusively reflect impairments of the "social brain". Evidence for atypical development of sensory and attentional systems highlight the need to move away from localized deficits to models suggesting brain-wide involvement in autism pathology. We discuss the implications infant sibs findings have for future work into the biology of autism and the development of interventions.

No MeSH data available.


Related in: MedlinePlus