School of Applied Physiology, Georgia Institute of Technology, 281 Ferst Dr., Atlanta, GA 30332-0356, USA.
Exp Brain Res. 2010 Jun;203(4):659-70. doi: 10.1007/s00221-010-2273-8. Epub 2010 May 6.
We used electroencephalography to see how the brain deals with altered sensory processing demands in lower extremity movements. In unimodal conditions, sensory processing demands were altered with subjects performing movement to a small or large visual target, or with a small or large weight to modify proprioception. In bimodal conditions, both weight and targets needed to be met. We assessed activity over primary sensorimotor, premotor and parietal areas before and during knee movements. In unimodal conditions, the primary sensorimotor area showed the least sensitivity to the maximally increased sensory demand in both vision and proprioception, while the premotor region was most sensitive to proprioceptive demands, and the parietal region showed greatest sensitivity to visual demands. In bimodal conditions, intermediate levels of sensory processing demand maximally increased activation at premotor and parietal regions. However, when visual and proprioceptive demands were both maximal, activation decreased and was similar to that seen with the lowest level of sensory processing demand. As behavior was consistent across conditions while activation at these regions decreased, we suggest that additional brain areas, possibly high order cognitive and attentional regions, may be required to augment the function of the traditional sensorimotor network in lower extremity movements with increasingly difficult sensory processing demands.
我们使用脑电图来观察大脑如何应对下肢运动中改变的感觉处理需求。在单模态条件下，通过让受试者向小或大的视觉目标移动，或使用小或大的重量来改变本体感觉，改变感觉处理需求。在双模态条件下，需要同时满足重量和目标。我们评估了膝关节运动前后初级感觉运动、运动前区和顶叶区域的活动。在单模态条件下，初级感觉运动区对视觉和本体感觉的最大感觉需求变化的敏感性最低，而运动前区对本体感觉需求的敏感性最高，顶叶区域对视觉需求的敏感性最高。在双模态条件下，中间水平的感觉处理需求最大程度地增加了运动前区和顶叶区域的激活。然而，当视觉和本体感觉需求都达到最大值时，激活减少，与最低水平的感觉处理需求相似。由于在这些区域的激活减少的情况下，行为在所有条件下保持一致，因此我们认为，可能需要更高阶的认知和注意力区域等额外的大脑区域，以增强传统的感觉运动网络在下肢运动中的功能，因为感觉处理需求变得越来越困难。
