Continuous versus Discontinuous Drawing: Possible Cerebellar Involvement in the Development of Temporal Consistency
Clark, Jane E
Contreras-Vidal, Jose L
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The capability to generate drawing and writing movements of high spatial and temporal qualities is one of the most important developmental achievements during the early school years. Recently, Spencer et al., (2003) proposed that the cerebellum controls the 'explicit timing' underlying temporal consistency during discontinuous drawing, but not 'implicit timing' during continuous drawing. Alternatively, the cerebellum might be involved in the control of limb dynamics, which differ between continuous and discontinuous drawing (Bastian et al., 2000). In the current study, we examine the hypothesis that the developing cerebellum might play an important role in the development of temporal consistency in drawing skills in children. Specifically, we examined: 1) whether there were age-related differences between continuous and discontinuous circle drawing, 2) whether the children's performance in the circle drawing tasks was the same as their performance in the dynamically simpler line drawing tasks, and 3) whether children with Developmental Coordination Disorder (DCD) performed similarly to the children who were typically developing in these four types of movements. Thirty-two children who were typically developing between the ages of five and eleven years and ten children with DCD performed the continuous, discontinuous circle- and line-drawing tasks in random order. Participants were asked to move as consistently as possible for 20 seconds after synchronizing their movements with a metronome for 15 beats. Regression analysis in children who were typically developing showed that high temporal variability existed only in the discontinuous circling in the youngest children but not the older children. Children with DCD showed a similar pattern to their age- and gender-matched controls. However, individual comparison for each child with DCD and normal performance defined by children who were typically developing revealed that two of the ten children with DCD showed timing deficit in the discontinuous movements, an additional three children had timing problem in the discontinuous line drawing. Limb dynamic control played an important role in the development of drawing skills in children. The possibility of a compromised cerebellar function may only exist in a subgroup of children with DCD supporting others observation of the heterogeneous nature of this population.