Real-time neurofeedback based on functional magnetic resonance imaging as a new approach to study the face processing network in autism spectrum.
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2019
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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 two days. Five subjects with ASD participated as part of the experimental group and
received contingent feedback to self-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 an inferior frontal gyrus, as observed in TD subjects. Recruitment of
inferior frontal gyrus was observed in both groups during FAA self-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 in ASD, and to
explore its clinical potential.
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Tesis (Doctor en Neurociencias)--Pontificia Universidad Católica de Chile, 2019