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Movement planning in Developmental Coordination Disorder

Movement planning in Developmental Coordination Disorder. Kate Wilmut , Maia Byrne and Anna Barnett. Action Sequences. Actions are composed of a string of movements, each movement taking into account the next

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Movement planning in Developmental Coordination Disorder

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  1. Movement planning in Developmental Coordination Disorder Kate Wilmut, Maia Byrne and Anna Barnett

  2. Action Sequences • Actions are composed of a string of movements, each movement taking into account the next • Internal forward modelling allows anticipation of motor consequences prior to execution (Wolpert & Kawato, 1998) • Allows a spatially and temporally optimal movement(Haggard, 1998; Rosenbaum, Vaughan, Barnes, & Jorgensen, 1992)

  3. Intended action • Intended action also effects initial kinematics of the reach-to-grasp when initial demands of a reach component are identical • In adults • Elongated deceleration phase for a fit vs. a throw action (Marteniuk et al. 1987) • Larger peak aperture and larger peak deceleration for a throwing/placing action vs. a lift action (Armbruster & Spijkers, 2006) • In children • 10 month-old infants: higher peak velocity when reaching to throw vs. place (Claxton, Keen, & McCarty, 2003) • 4 years of age: elongated deceleration period when reaching to fit vs. reaching to throw (Chen & Yang, 2007).

  4. Intended action IN DCD • DCD: explained by a deficit in the internal modelling of movement? (Maruff et al., 1999; Smits-Engelsman et al. 2007; Williams et al., 2006). • Difficulty predicting the outcome of action • If so we would not expect these individuals to tailor a movement to an onward action. • Aim: To consider whether children and adults with DCD tailor a movement to the onward action

  5. Participants • All reported current motor difficulties and none indicated any neurological deficit or comorbid condition that would explain their motor difficulties

  6. Grasped a cylinder and: • Tight place (hole x1) • Loose hole (hole x2) • Lift • Throw • A Vicon 3D motion capture system was used to track the movement of the thumb, index finger, knuckle and wrist of the dominant hand. METHOD

  7. Results: Movement Duration • DCD group showed a longer movement duration compared to the TD individuals. • TD – developmental improvement • DCD – no difference • Effect of action type: • TD group: Lift > tight place = loose place • DCD group: Lift > Throw

  8. Results: Proportion time in deceleration • DCD group spent a longer proportion of MT decelerating • TD – developmental improvement, DCD – no difference Effect of action type: • Adults: • TD: tight >loose=lift>throw • DCD: tight=loose=lift>throw • Children: • TD: tight=loose=lift>throw • DCD: no effect

  9. Effects of action type

  10. Effects of action type • Adults and children with DCD are able to concatenate actions and account for the onward action. • DCD group able to use internal forward modelling, even if it is not as sophisticated as that seen in TD adults. • Does it ever reach a fully mature level? • Is it driven by different underlying mechanism(s)? • Control of action in DCD is actually different to the typically developing population rather than simply delayed.

  11. Movement outcome • To some extent all of the groups tailored initial reach movement to the intended action • Does this result in a more functional movement? • For place movements: • How long spent adjusting prior to placing.

  12. Movement outcome Calculated % change in proportion of movement time spent decelerating from a tight place to a loose place Compared to the average adjustment time across tight and loose place trials.

  13. Movement outcome • Significant relationship for the TD adults, r=-0.532 p=0.023 • Pp who showed a greater discrimination in deceleration period from tight to loose place showed a shorter overall adjustment time • Not significant for the TD children, the adults with DCD or the children with DCD.

  14. Functionality of movement • If the children and adults with DCD are failing (even if only in some respects) to concatenate movement does this actually matter? • Seems to be a functionality to predicting onward action • TD adults: relationship between the degree to which they discriminated between the two place actions during the initial reach phase and the time spent adjusting

  15. Conclusions • Both adults and children with DCD seem able to use forward modelling of inverse models to anticipate movement and concatenate action. • Not as sophisticated as that seen in typically developing adults. • Underlying forward anticipation of action may be different, rather than simply delayed in DCD.

  16. Thank-you for listening Any questions?

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