Embryonic Exposure to Valproic Acid Affects Social Predispositions for Dynamic Cues of Animate Motion in Newly-Hatched Chicks.

Elena Lorenzi,Elisabetta Versace,Giorgio Vallortigara,Paola Sgadò,Orsola Rosa-Salva,Alessandra Pross

doi:10.3389/fphys.2019.00501

Elena Lorenzi, Elisabetta Versace + Show 4 more

Open Access

https://doi.org/10.3389/fphys.2019.00501

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Abstract

Early predispositions to preferentially orient toward cues associated with social partners have been documented in several vertebrate species including human neonates and domestic chicks. Human newborns at high familiar risk of Autism Spectrum Disorder (ASD) show differences in their attention toward these predisposed stimuli, suggesting potential impairments in the social-orienting mechanisms in ASD. Using embryonic exposure to valproic acid (VPA) we modeled ASD behavioral deficits in domestic chicks. To investigate social predispositions toward animate motion in domestic chicks, we focused on self-propulsion, using two video-animations representing a simple red circle moving at constant speed (speed-constant) or one that was changing its speed (accelerating and decelerating; speed-change). Using a spontaneous choice test for the two stimuli, we compared spontaneous preferences for stimuli that autonomously change speed between VPA- and vehicle-injected chicks. We found that the preference for speed changes was abolished in VPA-injected chicks compared to vehicle-injected controls. These results add to previous findings indicating similar impairments for static social stimuli and suggest a specific effect of VPA on the development of mechanisms that enhance orienting toward animate stimuli. These findings strengthen the hypothesis of an early impairment of predispositions in the early development of ASD. Hence, early predispositions are a potentially useful tool to detect early ASD symptoms in human neonates and to investigate the molecular and neurobiological mechanisms underlying the onset of this neurodevelopmental disorder.

Highlights

Neonates of some vertebrate species orient their first approach responses toward objects that exhibit features present in social partners and caregivers: face-like configuration, biological motion and self-propulsion
We investigated unlearned predispositions to orient toward animate motion cues in valproic acid (VPA)-injected chicks compared to vehicle-injected controls, using a choice preference test between a speed-change and a constant moving stimulus
We showed a detrimental effect of VPA on the typical spontaneous preference for the speed-change stimuli conveying animacy cues (RosaSalva et al, 2016)

Summary

INTRODUCTION

Neonates of some vertebrate species orient their first approach responses toward objects that exhibit features present in social partners and caregivers: face-like configuration, biological motion and self-propulsion. Neonates at high familiar risk of ASD show significant differences compared to low-risk neonates in the preference for a face-like stimulus and for biological motion, suggesting an impairment in the development of the predisposed mechanisms for detecting animate beings (Di Giorgio et al, 2016). Embryonic exposure to VPA has been shown to induce impairments in chicks’ aggregative behavior (Nishigori et al, 2013) and in their early predisposition for static stimuli (Sgadò et al, 2018). To further study the effect of VPA on early predispositions, and to investigate whether the impairment for static cues is accompanied by impairment in predispositions for dynamic cues, we compared the spontaneous preference for self-propelled stimuli in VPA- and vehicle-injected chicks

MATERIALS AND METHODS

RESULTS

Findings

ETHICS STATEMENT