Using Perceptual Signatures to Define and Dissociate Condition-Specific Neural Etiology: Autism and Fragile X Syndrome as Model Conditions

Abstract

The functional link between genetic alteration and behavioral end-state is rarely straightforward and never linear. Cases where neurodevelopmental conditions defined by a distinct genetic etiology share behavioral phenotypes are exemplary, as is the case for autism and Fragile X Syndrome (FXS). In this paper and its companion paper, we propose a method for assessing the functional link between genotype and neural alteration across these target conditions by comparing their perceptual signatures. In the present paper, we discuss how such signatures can be used to (1) define and differentiate various aspects of neural functioning in autism and FXS, and subsequently, (2) to infer candidate causal (genetic) mechanisms based on such signatures (see companion paper, this issue).

Attention across modalities as a longitudinal predictor of early outcomes: the case of fragile X syndrome

“…Fragile X syndrome (FXS) represents a model disorder in this respect because it is a well‐recognised cause of hereditary developmental delay, with an estimated incidence of 1 in 2,500 world‐wide (Hagerman, 2008), associated with the silencing of a single X‐linked gene (Garber, Visootsak, & Warren, 2008) and cases are identified as early as infancy, with an average diagnosis age of 37.9 months (Bailey, Raspa, Bishop, & Holiday, 2009). At the neurocognitive level, FXS is characterised by syndrome‐specific proficiencies and deficiencies that distinguish it from other neurodevelopmental disorders (Bertone, Hanck, Kogan, Chaudhuri, & Cornish, 2010). Highly notable are the striking visual attention difficulties (e.g.…”

“…These controlled stimuli allowed us to ensure that all children could discriminate targets similarly, as indeed demonstrated by performance in a separate task in which we established similar visual contrast thresholds for children with FXS and controls, t (60) = .254, p = .801, and selected stimuli for the attentional task that were clearly supra‐threshold for both groups. In contrast, using stimuli solely designed for TD individuals in standardised assessment tools could yield differences for perceptual (Bertone et al., 2010), rather than cognitive reasons.…”

Postural Hypo-Reactivity in Autism is Contingent on Development and Visual Environment: A Fully Immersive Virtual Reality Study

“…Visual information processing is also atypical in autism, defined by a “ perceptual signature ” characterized by superior performances on perceptual and cognitive tasks where local or detailed processing of spatial information is advantageous, and by a decreased ability or optional processing for complex types of information requiring either integrative, dynamic or global analysis (see Mottron and Burack 2001; Mottron et al 2006); Dakin and Frith 2005; Behrmann et al 2006; Bertone and Faubert 2006; Happe and Frith 2006; Simmons et al 2009; Bertone et al 2010; for reviews).…”

Increased Sensitivity to Mirror Symmetry in Autism

“…One proposal is that atypical development of perceptual functions ultimately results in a perceptual signature or profile that distinguishes autism from both typical development and other neurodevelopmental conditions [6], [7]. This signature takes into account findings of superior performance by autistics on a variety of visuospatial tasks, including visual search, block design, and embedded figures tasks [8]–[10].…”