The integrity of visual-proprioceptive mapping in cerebral palsy

Existing data on the ability of normal children to make intra-modal and cross-modal judgements about limb position are reviewed. A pattern of results emerges which suggests that although young children have difficulty with proprioceptive judgements, their performance is significantly enhanced if the task involves matching vision against proprioception. Some preliminary findings with cerebral palsied children suggest that this advantage may sometimes be lost. It is suggested, however, that the tasks used in previous studies do not allow the precise appraisal of this ability. This study examined intra- and cross-modal judgements in eight normal adults and eight severely cerebral palsied adolescents. In addition to the usual measures of spatial accuracy, joint angle measurements were recorded which allow some appraisal of the information strategy used for respective tasks. The results suggest that the cerebral palsied students had specific problems with mapping between vision and proprioception. This is discussed from a perspective of whether such mapping requires adaptive behaviour within a stable explorative environment, which is disrupted in cases of severe cerebral palsy.