Attention Demands in Balance Recovery following Lower Limb Amputation

The attention demands in balance control after damage to the peripheral sensorimotor system were studied in 12 persons with a recent lower limb amputation. The interference of an arithmetic task with two postural tasks of different complexity (quiet standing and active weight shifting) was examined several times during their rehabilitation while the subjects stood on a force platform. Control data were obtained from healthy subjects. For both postural tasks, persons with amputation performed worse than controls. Quiet standing, a relatively simple task, revealed clear dual-task interference only in the amputation group. Evidence was found for a reduction in dual-task interference as rehabilitation progressed. In contrast, voluntary (feedback-controlled) weight shifting, a more complex task, revealed an equal amount of dual-task interference in persons with amputation and in controls, without changes in interference over the period of rehabilitation. The results indicate that attentional mechanisms may be involved in postural control, depending on both the novelty and complexity of the task. Moreover, a reduction in attention demands of quiet standing may reflect a central adaptation of the postural organization to the peripheral sensorimotor impairments caused by lower limb amputation.