Bergenheim M, Ribot-Ciscar E, Roll J P
Division of Physiology, National Institute for Working Life, Umea, Sweden.
Exp Brain Res. 2000 Oct;134(3):301-10. doi: 10.1007/s002210000471.
The proprioceptive coding of multidirectional ankle joint movements was investigated, focusing in particular on the question as to how accurately the direction of a movement is encoded when all the proprioceptive information from all the muscles involved in the actual movement is taken into account. During ankle movements imposed on human subjects, the activity of 30 muscle spindle afferents originating in the extensor digitorum longus, tibialis anterior, extensor hallucis longus and peroneus lateralis muscles was recorded from the lateral peroneal nerve using the microneurographic technique. In the first part of the study, it was proposed to investigate whether muscle spindle afferents have a preferred direction, as previously found to occur in the case of cortical cells, and to analyze the neural coding of the movement trajectories using a "population vector model." This model is based on the idea that neuronal coding can be analyzed in terms of a series of vectors, each based on specific movement parameters. In the present case, each vector gives the mean contribution of a population of muscle spindle afferents within one directionally tuned muscle. A given population vector points in the "preferred sensory direction" of the muscle to which it corresponds, and its length is the mean frequency of all the afferents within that muscle. Our working hypothesis was that the sum of these weighted vectors points in the same direction as the ongoing movement. The results show that each muscle spindle afferent, and likewise each muscle, has a specific preferred sensory direction, as well as a preferred sensory sector within which it is capable of sending sensory information to the central nervous system. Interestingly, the results also demonstrate that the preferred directions are the same as the directions of vibration-induced illusions. In addition, the results show that the neuronal population vector model describes the multipopulation proprioceptive coding of spatially oriented 2D limb movements, even at the peripheral sensory level, based on the sum vectors calculated from all the muscles involved in the movement. In an accompanying paper, the coding of more complex 2D movements such as those involved in drawing rectilinear and curvilinear geometrical shapes was investigated.
研究了多方向踝关节运动的本体感觉编码，特别关注当考虑实际运动中所有相关肌肉的所有本体感觉信息时，运动方向的编码准确性问题。在对人体受试者施加踝关节运动期间，使用微神经图技术从腓骨外侧神经记录了起源于趾长伸肌、胫骨前肌、拇长伸肌和腓骨短肌的30条肌梭传入纤维的活动。在研究的第一部分，旨在调查肌梭传入纤维是否具有偏好方向，如先前在皮质细胞中发现的那样，并使用“群体向量模型”分析运动轨迹的神经编码。该模型基于这样的观点，即神经元编码可以根据一系列向量进行分析，每个向量基于特定的运动参数。在当前情况下，每个向量给出一个定向调谐肌肉内一群肌梭传入纤维的平均贡献。给定的群体向量指向与其对应的肌肉的“偏好感觉方向”，其长度是该肌肉内所有传入纤维的平均频率。我们的工作假设是这些加权向量的总和指向与正在进行的运动相同的方向。结果表明，每条肌梭传入纤维以及每块肌肉都有一个特定的偏好感觉方向，以及一个偏好感觉扇区，在该扇区内它能够向中枢神经系统发送感觉信息。有趣的是，结果还表明偏好方向与振动诱发幻觉的方向相同。此外，结果表明，基于从运动中涉及的所有肌肉计算出的总和向量，神经元群体向量模型描述了空间定向二维肢体运动的多群体本体感觉编码，即使在周围感觉水平也是如此。在一篇配套论文中，研究了更复杂的二维运动的编码，例如绘制直线和曲线几何形状所涉及的运动。
