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Daniel J. Weeks

This paper, presented as the C. Lynn Vendien International Lecture given at the National Academy of Kinesiology, September 2011, provides context around the concept of accountability, the roles of the Academy, and knowledge translation as the basis for a framework for continued development of the National Academy of Kinesiology. The intent is to use the concepts presented in this paper as a catalyst for further discussion on opportunities for the Academy to serve the field of kinesiology as a knowledge broker and champion in addressing matters of important societal importance. Disability is used as an example of one such immediate opportunity.

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Digby Elliott and Daniel J. Weeks

Discussed in this paper is the application of a neurobehavioral, functional systems approach to the understanding of verbal-motor integration difficulties experienced by persons with Down syndrome. In initial work, noninvasive neuropsychological techniques were used to examine both the similarities and differences in cerebral organization and perceptual-motor behavior between persons with Down syndrome and control subjects of the same chronological and/or mental age. This group-difference research led to the development of a specific model of brain-behavior relations in persons with Down syndrome. The main feature of the model is the neuroanatomical disconnection of the brain areas responsible for speech perception and movement organization. The basic tenets of the model are described, and efforts to test and refine it are discussed. This approach exemplifies how general neurobehavioral rules and principles can be harnessed to understand the exceptions to those rules often encountered with special populations.

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Digby Elliott, Susan Gray, and Daniel J. Weeks

The present study was designed to determine whether the verbal-motor performance deficits sometimes exhibited by Down syndrome persons interfere with their capacity to acquire a novel motor task. Mentally handicapped adults with and without Down syndrome, as well as nonhandicapped adults, practiced a verbally cued three-element movement sequence. When the verbal cue was terminated during retention, Down syndrome subjects made no more errors and performed the motor sequence just as rapidly as did the other mentally handicapped adults. However, Down syndrome subjects took longer to organize and initiate their movements. Both mentally handicapped groups performed more poorly than nonhandicapped subjects. The results provide partial support for the notion that Down syndrome persons have difficulty organizing limb movements on the basis of verbal instruction.

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Simon J. Bennett, Digby Elliott, Daniel J. Weeks, and Damian Keil

The aim of the present study was to examine the effects of intermittent binocular and monocular vision on the preparation and execution of the transport and grasp phases of prehension, and hence the temporal limit of binocular and monocular integration. Participants in two groups (speed or accuracy) performed prehensile movements of two amplitudes (20 and 40 cm) to either a large or small object (6 × 6 × 2 and 6 × 4 × 2 cm) under conditions of binocular and monocular viewing. The interval between visual samples was manipulated with liquid crystal goggles (continuous vision, 20on/60off, and 20on/120off ms). A kinematic analysis indicated that participants modified variables associated with the preparation and execution of prehension in the intermittent vision conditions when instructed to emphasize accuracy. Participants instructed to emphasize speed, modified variables associated with the preparation phase only. The impact of intermittent vision was similar under binocular and monocular viewing. Thus, for prehension, it appears that consecutive binocular or monocular samples need to occur less than 60 ms apart in order to be fully integrated for limb control.

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Shannon D. Ringenbach, Romeo Chua, Brian K. V. Maraj, James C. Kao, and Daniel J. Weeks

Previous experiments involving discrete unimanual tasks have shown that individuals with Down syndrome (DS) have auditory/verbal-motor deficits. The present study investigated unimanual and bimanual continuous perceptual-motor actions in adults with DS. Ten adults with DS, 10 typical adults, and 10 children drew continuous circles at increasing periods bimanually and unimanually with each hand. Movement was paced by either a visual or an auditory metronome. The results revealed that for circle shape and coordination measures, children and adults were more accurate with the visual metronome, whereas adults with DS were more accurate with the auditory metronome. In the unimanual tasks, adults with DS displayed hand asymmetries on spatial measures. In the bimanual task, however, adults with DS adopted an in-phase coordination pattern and stability more similar to adults than children. These results suggest that bimanual coordination in adults with DS is functioning effectively despite hand asymmetries evident in unimanual performance.

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Shannon D.R. Ringenbach, Kristina Zimmerman, Chih Chia Chen, Genna M. Mulvey, Simon D. Holzapfel, Daniel J. Weeks, and Michael H. Thaut

The present study used a synchronization-continuation paradigm during continuous bimanual drumming with different cues in 17 persons with Down syndrome, eight typical persons with similar mental age and eight typical persons with similar chronological age. The task required participants to hit two drums with their hands at the same time following music (e.g., a tune with various decibel drum beats), auditory (e.g., sound of drumbeat), verbal (e.g., voice saying “drum”), and visual (e.g., video of both hands moving up and down and hitting the drums together) cues for 10 seconds, then continue drumming in the absence of cues for another 10 seconds. In general, when all groups were following the music cues their movements were faster as compared with their movements in the auditory, verbal, and visual conditions. In addition, when following visual cues all groups produced more accurate and consistently coordinated movements than with the other cue types. Further, participants with Down syndrome often stopped moving when the pacing cues were eliminated indicating a need for continuous cues for continuous movements.