This study aimed to (1) to compare motor functioning profiles between the autistic and TD preschoolers at 4-6 years of age; (2) to measure cortical activation pattern during hand imitation tasks in both frontal and motor areas including prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor cortex (SMC) areas with fNIRS, and to examine its differences between groups.
Autistic and TD children received motor assessments of the Peabody Developmental Motor Scales 2nd Edition (PDMS-2) and Movement Assessment Battery for Children-2nd Edition (MABC-2). Furthermore, each participant completed three conditions of hand imitation tasks: (a) Watch: the child observes the experimenter collecting the building blocks; (b) Do: the child collects the building blocks with their dominant hand; (c) Together: the child and the experimenter collect the building blocks at the same time, with the child mirroring the experimenter's actions. A multichannel wearable fNIRS imaging system with 8 LED light sources and 8 detectors, which are attached on subjects’ heads was used to detect the hemodynamics of the bilateral PFC, SMA, and PMC.
Ten autistic children and 28 TD children have participated in this study. Autistic children showed significantly lower fine and gross motor scores in the PDMS-2; and lower motor Aiming and Catching as well as Balance subscale scores of MABC-2 compared to the TD group (all p 0.05). In terms of cortical activation during the hand imitation tasks, autistic children showed hyperactivation in the PMC during the Watch condition [HbO2 value: ASD= 0.169 vs. TD= (-0.006); p =0.04)]; and in the SMC during the Do condition compared to the TD children [HbO2 value: ASD= 0.402 vs. TD= (-0.039); p =0.0005)]. For brain activation during each condition within each group, autistic children showed hyperactivation in the PMC and SMC during the Do condition; whereas hypoactivation in the SMC during the Together condition (all p 0.05).
The results of this study revealed significant differences in motor functioning and brain activation between Autistic and TD preschoolers. The PFC, SMA and PMC play important roles in planning motor action and guiding self-initiated motor control. Our findings identified objective neural biomarkers in those brain areas that might related to hand imitation skills for autistic children.
Although the number of autistic preschoolers is small, the findings might help to preliminary understand the relevance between early motor functioning and brain activation among autistic children, thereby developing neurobiological indicators to facilitate early detection and treatment for ASD.
Motor Imitation
Brain Activation
