Motor kinematic differences in children with autism sepectrum disorder : ecological gameplay with a sensorised toy

Background Evidence suggests gross motor differences are present in children with Autism Spectrum Disorder (ASD) from birth. Trevarthen and Delafield-Butt (2013) proposed that one of the early markers of ASD are abnormalities in the development of intentional movements, which are present before the manifestations of symptoms typically associated with autism, like deficiencies in social interaction and communication. A growing body of literature demonstrates kinematic and action patterns differences in children and adults with ASD. However, these experiments typically require expensive laboratory-based optical motion tracking systems. Here, we developed bespoke, sensorised wooden cubes for motor assessment of children’s play and report on the kinematic and action pattern differences of the children with autism compared to children developing typically. Objectives A description of ASD-specific action patterns and kinematics using sensorised toys. Methods Participants. Children 3 to 5 years diagnosed with ASD (n = 15) recruited from the Scottish Centre for Autism, Glasgow, UK. Children 3 to 5 years old developing typically recruited from nurseries in Glasgow, UK. Adults 20 to 25 years old without ASD recruited from Glasgow, UK. The study was approved by the University of Strathclyde Ethics Committee and consent obtained from the parents of children or the adults. In the case of the children with ASD, pre-screening with Vineland-II, AQ-Child and Leiter-R Brief IQ was performed. Procedure. The children were seated at a table and instructed to play two simple games that involved moving the cube from one position to another: a Serially Organized Action (SOA) game and a Single Repetitive Action (SRA) game. The first required complex motor sequencing and engagement with the experimenter, while the second consisted of a simple repetitive movement. Each game produced a single measured movement to a goal with 25 iterations or repetitions to yield 50 movements in total. An electronic board inside the cubes was equipped with tri-axial magnetometer, gyroscope and accelerometer wirelessly transferred the cube’s motion data to a laptop. The signal (raw motion data) was extracted through a Matlab-based platform and analysed. Data Analysis. Kinematic features of movement duration; maximum value of acceleration, velocity, and jerk during each movement; time to maximum value; % duration to maximum value; and the acceleration, velocity, and jerk action patterns profiles were calculated. Results The jerk profile of children with ASD was significantly different, showing increased maximum jerk, reduced time to maximum value and & duration to maximum value, and lower variability than typically developing children. Further, movement duration was shorter compared to age-matched typically developing children, and maximum velocity was significantly higher in children with ASD compared to children developing typically. Conclusion The increased jerk values and onset times in the ASD group are a particularly interesting finding that support new data appearing by other groups. It appeared, especially in the SRA game, that when moving the cube from one position to the next, the children with autism impacted on the surface of the table with greater velocity and typically included the resulting force immediately into to the next movement, giving it a greater jerk value in a shorter span of time that typically children. Typically developing children, on the other hand, paused for a moment (>100 ms) before commencing the next movement. Further, children with autism did not enjoy the SRA game, but they did enjoy the simpler, more repetitive SOA one. The repetitive simplicity of the SOA game and its resulting jerk profile appears to report on a particular behavioural motor feature distinct to ASD, namely stopping an action and starting a new one, while also describing an underlying motor difference that may contribute to it

Synergistic warm inflation

We consider an alternative warm inflationary scenario in which $n$ scalar fields coupled to a dissipative matter fluid cooperate to produce power--law inflation. The scalar fields are driven by an exponential potential and the bulk dissipative pressure coefficient is linear in the expansion rate. We find that the entropy of the fluid attains its asymptotic value in a characteristic time proportional to the square of the number of fields. This scenario remains nearly isothermal along the inflationary stage. The perturbations in energy density and entropy are studied in the long--wavelength regime and seen to grow roughly as the square of the scale factor. They are shown to be compatible with COBE measurements of the fluctuations in temperature of the CMB.Comment: 13 pages, Revtex 3 To be published in Physical Review