Budri Mirco, Lodi Enrico, Franchi Gianfranco
Section of Human Physiology, Department of Biomedical and Specialty Surgical Sciences, University of Ferrara Ferrara, Italy.
Front Syst Neurosci. 2014 Dec 12;8:231. doi: 10.3389/fnsys.2014.00231. eCollection 2014.
Long-duration intracortical microstimulation (ICMS) studies with 500 ms of current pulses suggest that the forelimb area of the motor cortex is organized into several spatially distinct functional zones that organize movements into complex sequences. Here we studied how sensorimotor restriction modifies the extent of functional zones, complex movements, and reachable space representation in the rat forelimb M1. Sensorimotor restriction was achieved by means of whole-forelimb casting of 30 days duration. Long-duration ICMS was carried out 12 h and 14 days after cast removal. Evoked movements were measured using a high-resolution 3D optical system. Long-term cast caused: (i) a reduction in the number of sites where complex forelimb movement could be evoked; (ii) a shrinkage of functional zones but no change in their center of gravity; (iii) a reduction in movement with proximal/distal coactivation; (iv) a reduction in maximal velocity, trajectory and vector length of movement, but no changes in latency or duration; (v) a large restriction of reachable space. Fourteen days of forelimb freedom after casting caused: (i) a recovery of the number of sites where complex forelimb movement could be evoked; (ii) a recovery of functional zone extent and movement with proximal/distal coactivation; (iii) an increase in movement kinematics, but only partial restoration of control rat values; (iv) a slight increase in reachability parameters, but these remained far below baseline values. We pose the hypothesis that specific aspects of complex movement may be stored within parallel motor cortex re-entrant systems.
对持续500毫秒电流脉冲的长时间皮层内微刺激（ICMS）研究表明，运动皮层的前肢区域被组织成几个空间上不同的功能区，这些功能区将运动组织成复杂的序列。在这里，我们研究了感觉运动限制如何改变大鼠前肢M1中功能区的范围、复杂运动和可及空间表征。通过对整个前肢进行为期30天的石膏固定来实现感觉运动限制。在去除石膏后的12小时和14天进行长时间ICMS。使用高分辨率3D光学系统测量诱发的运动。长期石膏固定导致：（i）可诱发复杂前肢运动的位点数量减少；（ii）功能区缩小但其重心无变化；（iii）近端/远端共同激活的运动减少；（iv）运动的最大速度、轨迹和矢量长度降低，但潜伏期或持续时间无变化；（v）可及空间大幅受限。石膏固定后14天的前肢自由导致：（i）可诱发复杂前肢运动的位点数量恢复；（ii）功能区范围和近端/远端共同激活的运动恢复；（iii）运动运动学增加，但仅部分恢复到对照大鼠的值；（iv）可达性参数略有增加，但仍远低于基线值。我们提出假说，即复杂运动的特定方面可能存储在并行的运动皮层折返系统中。
