Altered behavioral and amygdala habituation in high-functioning adults with autism spectrum disorder: an fMRI study

Friederike I Tam,Julius Steding,Daniel Geisler,Stefan Ehrlich,Joseph A King,Katja U Albertowski,Juliane Sareng,Veit Roessner,Franziska Ritschel,Franziska M Korb

doi:10.1038/s41598-017-14097-2

Abstract

Habituation to repeatedly presented stimuli is an important adaptive property of the nervous system. Autism spectrum disorder (ASD) has been associated with reduced neural habituation, for example in the amygdala, which may be related to social impairments. The main focus of this study was to investigate habituation effects on the level of behavioral responses as well as amygdala responses in adults with ASD during a working memory task flanked by task-irrelevant face stimuli. Twenty-two patients with high-functioning autism and 24 healthy controls (HC) were included in this functional magnetic resonance imaging (fMRI) study. We employed an established habituation index to investigate habituation effects. Suggestive of altered habituation, the habituation index showed a decrement of reaction time over the course of the experiment in the HC but not in the ASD group. Similarly, an expected pattern of habituation was evident in amygdala activation in HC but absent in ASD participants. These results provide evidence that habituation may be altered not only on a neural, but also on a behavioral level in ASD. While more research is needed to develop a better understanding of the underlying mechanisms, the current findings support the possibility that deficient habituation may be a biomarker of ASD.

Highlights

Autism spectrum disorder (ASD) is a pervasive developmental disorder characterized by persistent deficits in social communication and interaction and restricted, repetitive patterns of behavior, interests, or activities
To gain insight on the potential underlying mechanisms of social impairments in ASD, we tested the notion of reduced habituation both on the level of behavioral responses as well as amygdala activation to face stimuli in a sample of adults with high-functioning ASD relative to healthy controls (HC) subjects
We employed a 2-back working memory task flanked by faces with different emotions as task-irrelevant distractors and a habituation index b’ recently used to test amygdala habituation[17,27]

Summary

Introduction

Autism spectrum disorder (ASD) is a pervasive developmental disorder characterized by persistent deficits in social communication and interaction and restricted, repetitive patterns of behavior, interests, or activities. To gain a broader understanding of the underlying mechanisms of abnormalities in emotional processing and social impairment in ASD, the current study investigated amygdala habituation to face stimuli in a sample of high-functioning adults with ASD. To this end, we analyzed behavioral and functional magnetic resonance imaging (fMRI) data acquired during an adapted emotional face n-back task similar to that introduced by Ladouceur et al.[26]. We predicted that habituation would be reduced or absent in ASD as gauged by both behavioral performance and amygdala activation

Objectives

Methods

Conclusion