Valle M S, Bosco G, Poppele R E
Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Catania, Italy.
Department of Neuroscience and CBMS, University of Rome "Tor Vergata", Rome, Italy.
Exp Brain Res. 2017 Nov;235(11):3437-3448. doi: 10.1007/s00221-017-5067-4. Epub 2017 Aug 23.
We previously showed that proprioceptive sensory input from the hindlimbs to the anterior cerebellar cortex of the cat may not be simply organized with respect to a body map, but it may also be distributed to multiple discrete functional areas extending beyond classical body map boundaries. With passive hindlimb stepping movements, cerebellar activity was shown to relate to whole limb kinematics as does the activity of dorsal spinocerebellar tract (DSCT) neurons. For DSCT activity, whole limb kinematics provides a solid functional framework within which information about limb forces, such as those generated during active stepping, may also be embedded. In this study, we investigated this idea for the spinocerebellar cortex activity by examining the activity of cerebellar cortical neurons during both passive bipedal hindlimb stepping and active stepping on a treadmill. Our results showed a functional compartmentalization of cerebellar responses to hindlimb stepping movements depending on the two types of stepping and strong relationships between neural activities and limb axis kinematics during both. In fact, responses to passive and active stepping were generally different, but in both cases their waveforms were related strongly to the limb axis kinematics. That is, the different stepping conditions modified the kinematics representation without producing different components in the response waveforms. In sum, cerebellar activity was consistent with a global kinematics framework serving as a basis upon which detailed information about limb mechanics and/or about individual limb segments might be imposed.
我们之前的研究表明，猫后肢向前庭小脑皮质的本体感觉输入可能并非简单地按照身体图谱进行组织，而是可能分布于多个离散的功能区域，这些区域超出了经典身体图谱的边界。在被动后肢踏步运动中，小脑活动与整个肢体的运动学相关，背侧脊髓小脑束（DSCT）神经元的活动也是如此。对于DSCT活动而言，整个肢体的运动学提供了一个坚实的功能框架，在这个框架中，关于肢体力量的信息，比如在主动踏步过程中产生的力量信息，也可能被嵌入其中。在本研究中，我们通过检查小脑皮质神经元在被动双足后肢踏步和在跑步机上主动踏步过程中的活动，来探究脊髓小脑皮质活动的这一观点。我们的结果显示，小脑对后肢踏步运动的反应存在功能分区，这取决于两种踏步类型，并且在这两种情况下，神经活动与肢体轴运动学之间都存在很强的相关性。事实上，对被动和主动踏步的反应通常是不同的，但在两种情况下，它们的波形都与肢体轴运动学密切相关。也就是说，不同的踏步条件改变了运动学表征，但在反应波形中并未产生不同的成分。总之，小脑活动与一个全局运动学框架一致，该框架可作为一个基础，在其上可能会施加有关肢体力学和/或单个肢体节段的详细信息。
