White matter structure in the uncinate fasciculus: Implications for socio-affective deficits in Autism Spectrum Disorder

Abstract

a b s t r a c tIndividuals with Autism Spectrum Disorder (ASD) have social and communication deficits and difficulties regulating emotions. The brain bases of these socio-affective deficits are not yet clear, but one candidate is structural connectivity in the left uncinate fasciculus, which connects limbic temporal and frontal areas thought to be involved in socio-affective processing. In this study, we assessed white matter structure in the left and right uncinate fasciculus in 18 high-functioning individuals with ASD and 18 group-matched typically developing (TD) controls using Diffusion Tensor Imaging. To test specificity of the associations, we also examined the association between both uncinate fasciculi and restricted and repetitive behaviors. Compared to TD individuals, individuals with ASD had significantly lower fractional anisotropy (FA) in the left and right uncinate. Group status significantly moderated the association between left uncinate and socio-affective deficits, indicating that within the ASD group, FA was associated with socio-affective deficits: Individuals with ASD with lower FA in the left uncinate had significantly more social and emotion regulation deficits. There was no association with restricted and repetitive behaviors. This study provides evidence that the left uncinate may play a critical role in socio-affective skills in individuals with ASD.

Emotion regulation in autism spectrum disorder: Where we are and where we need to go

“…More than half of these studies included participants with ASD who had average cognitive capacity overall, whilst other studies either included individuals with lower cognitive capacity or did not provide information regarding participants' cognitive function. Poor ER may be inherent in ASD [Mazefsky et al, ; Mazefsky & White, ], and recent evidence supports this view [e.g., Konstantareas & Stewart, ; Nader‐Grosbois & Mazzone, ; Pitskel, Bolling, Kaiser, Pelphrey, & Crowley, ; Richey et al, ; Samson et al, ; Samson et al, ]. All ASD core symptoms have been shown to be linked to emotion dysregulation [Berkovits, Eisenhower, & Blacher, 2017], with restricted and repetitive behaviors, interests, and activities being the strongest predictor [Samson et al, ].…”

“…Secondly, these regions show atypical patterns of activation in ASD across a range of executive function tasks [Minshew & Keller, 2010; Schmitz et al, ; Shafritz, Dichter, Baranek, & Belger, ; Kana, Keller, Minshew, & Just, ], which may explain the deficits in cognitive reappraisal observed in ASD. Finally, research has shown there is less connectivity between frontal regions and the lower limbic brain in individuals with ASD [Samson et al, ], and during tasks involving down‐regulation of negative emotions, there is decreased engagement of prefrontal regions and lack of amygdala down‐regulation in ASD [Pitskel et al, ; Richley et al 2015]. It is apparent that these two separate streams of neurological research, one examining executive function and the other emotion regulation, are largely related.…”

Imbalance of Laminar-specific Excitatory and Inhibitory Circuits of the Orbito frontal Cortex in Autism

“…The decreased density of OFC neurons and axons in adults with ASD observed in our study, provides evidence for parallel development of pathology in amygdala and OFC in ASD. This is also supported by functional studies that showed reduced amygdala-OFC activity in adults with ASD [65], and structural studies that showed reduced tract volume and lower mean fractional anisotropy values in the uncinate fasciculus, the axon bundle connecting OFC and the temporal lobe, including the amygdala [28,29,89].…”

White Matter Features Associated With Autistic Traits in Obsessive-Compulsive Disorder

“…Further, FA in the UF correlated with therapy duration and clinical outcome as measured by the Child Autism Rating Scale ( 74 ). Samson et al ( 75 ) assessed WM alteration in 18 ASD group and typically developed (TD) controls, and investigated the relationship between FA in UF using DTI and socio-affective deficit. They reported that ASD group had lower FA in left UF than TD, and within ASD group, FA was related to socio-affective deficit ( 75 ).…”

“…Samson et al ( 75 ) assessed WM alteration in 18 ASD group and typically developed (TD) controls, and investigated the relationship between FA in UF using DTI and socio-affective deficit. They reported that ASD group had lower FA in left UF than TD, and within ASD group, FA was related to socio-affective deficit ( 75 ). These results would support the correlation between AQ representing autistic traits and UF features in the current study, but it would be difficult to evaluate whether our subjects had socio-emotional deficits without functional data of socio-emotional function.…”