31896
The Development of Frontal Cortex of the Adolescent with Autism Spectrum Disorders (ASD) and Its Relationship with Working Memory
Working memory (WM) is one of the core components of executive function, which plays a central role in the pathology of Autism Spectrum Disorders (ASD). Although high-functioning autism (HFA) tend to have a normal range of IQ, WM is a main impact on the daily life. Adolescence is a period in which WM becomes increasingly important, but the supported brain regions like frontal cortex are still immature. Thus, the development of these brain regions and its relationship with WM ability, severity of adolescent HFA is extremely interesting.
Objectives:
This study aimed to investigate the development of the frontal cortex of the HFA. The resting-state connectivity and graph metrics were computed through the time course signals measured by an fNIRS device. The relationship between the neuroimaging results and the WM ability, severity of autism was also evaluated.
Methods:
In total, 12 typically developing (TD) children, 14 children with ASD and 18 adolescents with ASD were recruited. The IQ was measured by the Wechsler Intelligence Scale for Children (WISC-IV), and the diagnostic of ASD was confirmed by ADOS. All the participants were asked to close the eyes and sit still in a dark and quite room for 8 mins during the experiment. 13 emitters and 12 detectors were attached to the forehead forming 40 measuring channels, which covered the middle frontal gyrus (MFG), superior frontal gyrus (SFG), dorsolateral prefrontal cortex (DLPFC) and the supplementary motor cortex (SMA). The motion artifacts and physiological noise were first removed, and then the Pearson correlation coefficient r between DLPFC and all the other channels was calculated. the small worldness, network efficiency, betweenness centrality, degree was computed using a network sparsity threshold between 16% and 35% in increments of 1%. The area under the curve (AUC) was also obtained for each metric to avoid dependence on threshold levels.
Results:
Compared to children with ASD, adolescents with ASD showed lower connectivity between right SMA and bilateral DLPFC (p=0.022; p=0.021), and higher between left DLPFC and right SFG (p=0.012). The graph analysis revealed adolescents with ASD showed lower network efficiency than TD group (p=0.004) and children with ASD group (p=0.004). Moreover, the study found that the adolescents with ASD group showed lower betweenness centrality, the degree and the nodal efficiency in channels within the DLPFC (p<0.05). Meanwhile the connectivity between bilateral DLPFC in the children with ASD group was significantly correlated with working memory index of WISC-IV (r=0.540, p=0.046), and the network efficiency of children with ASD group was correlated with the repetitive scores of ADOS (r=-0.681, p=0.010). The betweenness centrality of left DLPFC of adolescents with ASD group negatively correlated with working memory index (r=-0.493, p=0.038). The degree and nodal efficiency of left DLPFC of both ASD groups were negatively correlated with communication and reciprocal interaction of ADOS (p<0.05).
Conclusions: T
his atypical neural developmental trajectory of DLPFC related to the WM ability and severity of adolescent HFA. The DLPFC seemed to follow a “posterior to anterior” pattern in ASD, which was the opposite to that of TD.