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Title: Functional brain imaging of facial emotion processing in individuals with intellectual impairments
Author: McKechanie, Andrew Graeme
ISNI:       0000 0004 9348 9916
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2020
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From the relatively early descriptions of fragile X syndrome, it was recognised that there were differences in social communication, which overlapped or mirrored those seen in idiopathic autism. And in parallel, genetic screening of individuals with autism revealed fragile X syndrome as a leading inherited cause of autism. Reviewing the literature of both of these conditions; it is obvious that although as clinical entities they include individuals with varying degrees of cooccurring intellectual disabilities or impairments, the existing literature has largely included those who are more, or most, intellectually able. This is particularly so in brain imaging research, largely by reason of the significant challenges of the imaging environment, with many of the challenges of having a scan corresponding with particular difficulties for the individuals; e.g. the noise of the scanner being of particular difficulty for those with sensory hypersensitivities (common in fragile X syndrome and autism). In the current study, functional brain imaging was used to investigate the role of autism in the processing of facial emotions in two cohorts – one with special educational needs and one with fragile X syndrome. Particular consideration was given to whether the emerging patterns of activations in any way mirrored those seen in the extant literature and whether to any degree it could be considered that autism in the context of lower cognitive ability (be that by virtue of idiopathic intellectual impairment or a known single-gene disorder) has the same underlying neural correlates as in individuals of average or above average intellect. In a group of individuals with special educational needs, it was found that those with high autistic traits had a region of hyperactivation to neutral faces in the right rolandic operculum; replicating a finding previously described in a metaanalysis of prior functional imaging studies in individuals with autism and of average or enhanced cognitive ability. In parallel, the sub-group with low autistic traits had a cluster of significantly greater activation in the left supramarginal gyrus / angular gyrus in response to fearful facial stimuli compared to the autistic sub-group. This pattern of relative hypo-activation in individuals with autism to emotional stimuli is typical of the existing literature in autism and adds further weight to the idea that, at least in part, individuals with autism of lower cognitive ability show similar changes in neural function. In a group of individuals with fragile X syndrome, those with high autistic traits had a cluster of significantly lower brain activation in the left superior temporal gyrus / left supramarginal gyrus in response to fearful faces when compared to those with low autistic traits. This cluster overlapped previous findings in both the fragile X literature, but also prior work in the broader autism literature, suggesting that autism in the context of a monogenic form of ID may have similar neurobiological correlates as seen in idiopathic autism. The results from this study show firstly that imaging individuals with significant cognitive impairments is feasible. Secondly, the results suggest that autistic individuals who have concurrent intellectual impairments share some of the same patterns of brain function as seen in autistic individuals of average or enhanced cognitive ability, who are most commonly recruited for brain imaging studies. Finally, the results suggest that autistic traits in the context of fragile X syndrome are associated with brain activation differences, which overlap those previously described in idiopathic autism. Further research is necessary to quantify the nature and degree of this overlap more fully.
Supervisor: Stanfield, Andrew ; Lawrie, Stephen ; Sibley, Heather Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: fragile X syndrome ; autism ; functional brain imaging ; intellectual impairment ; intellectual disability