Abstract
One of the most important and early impairments in autism spectrum disorder (ASD) is the abnormal visual processing of human faces. This deficit has been associated with hypoactivation of the fusiform face area (FFA), one of the main hubs of the face-processing network. Neurofeedback based on real-time fMRI (rtfMRI-NF) is a technique that allows the self-regulation of circumscribed brain regions, leading to specific neural modulation and behavioral changes. The aim of the present study was to train participants with ASD to achieve up-regulation of the FFA using rtfMRI-NF, to investigate the neural effects of FFA up-regulation in ASD. For this purpose, three groups of volunteers with normal I.Q. and fluent language were recruited to participate in a rtfMRI-NF protocol of eight training runs in 2 days. Five subjects with ASD participated as part of the experimental group and received contingent feedback to up-regulate bilateral FFA. Two control groups, each one with three participants with typical development (TD), underwent the same protocol: one group with contingent feedback and the other with sham feedback. Whole-brain and functional connectivity analysis using each fusiform gyrus as independent seeds were carried out. The results show that individuals with TD and ASD can achieve FFA up-regulation with contingent feedback. RtfMRI-NF in ASD produced more numerous and stronger short-range connections among brain areas of the ventral visual stream and an absence of the long-range connections to insula and inferior frontal gyrus, as observed in TD subjects. Recruitment of inferior frontal gyrus was observed in both groups during FAA up-regulation. However, insula and caudate nucleus were only recruited in subjects with TD. These results could be explained from a neurodevelopment perspective as a lack of the normal specialization of visual processing areas, and a compensatory mechanism to process visual information of faces. RtfMRI-NF emerges as a potential tool to study visual processing network in ASD, and to explore its clinical potential.
Highlights
Autism spectrum disorder is a chronic, burdensome (Howlin et al, 2004; Weiss and Lunsky, 2011; Beecham, 2014), highly prevalent neurodevelopmental condition (Kim et al, 2011; Fisch, 2012), and strongly associated with medical and psychiatric comorbidities (Lai et al, 2014)
There were no significant group differences in the accuracy achieved in the visual processing tasks (Table 3), participants with typical neural development (TD) showed a faster reaction time in the standardized face memory task (CFMT) compared to the nonsocial memory task (CCMT) (CFMT Mdn = 3291; CCMT Mdn = 5054; U = 5, p = 0.0411, Mann–Whitney U test)
This is the first research to show that the neural networks involved in the visual processing of faces can be studied in participants with autism spectrum disorder (ASD) using fusiform face area (FFA) up-regulation with rtfMRINF
Summary
Autism spectrum disorder is a chronic, burdensome (Howlin et al, 2004; Weiss and Lunsky, 2011; Beecham, 2014), highly prevalent neurodevelopmental condition (Kim et al, 2011; Fisch, 2012), and strongly associated with medical and psychiatric comorbidities (Lai et al, 2014). One of the most important and early impairments in ASD is the abnormal visual processing of human faces (Baron-Cohen et al, 2001a; Calder et al, 2002; Weigelt et al, 2012; Klin et al, 2015). This deficit has been associated with a lack of the typical attentional bias toward social stimuli – mainly faces – that is observed in people with TD from early childhood and throughout life (Dawson et al, 2005; Simion and Giorgio, 2015). Rapid facial processing is necessary for the development of more complex socially relevant cognitive functions (GarcíaVillamisar et al, 2010), such as inter-subjectivity (Yirmiya et al, 1992), pragmatic communication (Mundy et al, 1992) or Theory
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