Differential control of H-reflex amplitude in different weight-bearing conditions in young and elderly subjects
Differential control of H-reflex amplitude in different weight-bearing conditions in young and elderly subjects
复制标题
年轻和老年受试者不同负重条件下 H 反射幅度的差异控制
DOI：
10.1016/j.clinph.2012.03.006
复制
发表时间：
2013
影响因子：
4.7
通讯作者：
et al.
中科院分区：
文献类型：
--
作者：
Tsuruike;Kitano;et al.
方法对14名老年受试者和11名青年受试者在6种不同的负重状态下：(1)仰卧位，(2)仰卧位，(2)仰卧位倾斜30°，(4)站立50%，(5)100%和(6)125%WB。结果与年轻人相比，老年受试者在WB状态下的背景比目鱼肌肌电活动持续较高。股神经调节导致H反射的易化，在年轻受试者中，H反射在不同的WB条件下发生变化，但在老年受试者中没有。结论老年人可能有更多的运动神经元从下行通路直接激活，同时脊髓对抑制性中间神经元的节段性控制较少，这从背景比目鱼肌活动、H/M-max比值的增加以及在调节H反射时观察到的缺乏调制控制来证明。
OBJECTIVEThis study measured the modulation of conditioned (femoral nerve, paired-stimuli) and unconditioned soleus H-reflexes in young and elderly subjects when changing weight-bearing (WB) requirements and body position.METHODSConditioned and unconditioned H-reflexes were examined in 14 elderly subjects and 11 young subjects during six different WB conditions: (1) lying supine with no WB, (2) supine position inclined by 30° with 50% WB, (3) standing with 50%, (4) 75%, (5) 100% and (6) 125% WB.RESULTSThe elderly subjects had consistently higher background soleus EMG activity across the WB conditions compared to the young. Femoral nerve conditioning caused facilitation of the H-reflex that changed across WB conditions in the young subjects, but not in the elderly subjects. Finally, elderly subjects had less depression with paired-stimulation (PRD) across WB conditions, which was not observed in the young subjects.CONCLUSIONSThe elderly may have more direct activation of motoneurons from descending pathways, coupled with less segmental spinal control of inhibitory interneurons, as evidenced by the increased background soleus activity, H/M-max ratios and the lack of modulatory control observed when conditioning the H-reflex.SIGNIFICANCEThere was an age-specific response from descending and segmental pathways during conditions that involved either different WB requirements or changes in body position.