The long-term goal of this research is to understand the development of balance control in children with cerebral palsy (CP), and to determine how impairments in visual, somatosensory, and balance control limit the development of functionally independent mobility and reaching skills. The primary focus of previous balance research in this population has been to understand the neuromuscular constraints that limit static balance. We propose to extend this research to examine the sensory and attentional constraints on balance control during the dynamic conditions of gait and reaching. The first specific aim of the grant is: To determine the limitations on response capabilities faced by the child with cerebral palsy when confronted with threats to balance during walking. Four alternative hypotheses have been proposed to account for balance deficits during recovery from slips: 1) reduced postural response magnitudes, specifically in the ankle muscles; 2) slowed muscle response onsets, 3) increased co-activation of agonist-antagonist muscles, leading to a reduced efficiency of the response 4) an inappropriate activation sequence, with proximal muscles or antagonist muscles activated before distal agonists.
In specific aim 2, we will also study balance of children with CP under dual task conditions (balancing while performing a secondary task), another context with a high risk of falls. In this specific aim we will determine the attentional requirements of postural control in children with CP and whether the addition of a secondary attentional task causes deterioration in their postural control during locomotion. We hypothesize that children with visual spatial processing deficits will show reduced postural control when performing a secondary visual attention task, since the postural system also requires visual spatial processing. Finally, in specific aim 3 we will determine the extent to which a reduced ability to activate anticipatory postural adjustments before reaching contributes to reduced eye-hand coordination accuracy in children with cerebral palsy. Experiments will be performed to test the above hypotheses, using electromyographic, kinetic and kinematic analyses. In each specific aim we will examine the extent of the relationship between the motor dysfunction observed and the sensory capabilities of the children with CP.
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