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Intra-limb modulations of posterior root-muscle reflexes evoked from the lower-limb muscles during isometric voluntary contractions
Experimental Brain Research ( IF 2 ) Pub Date : 2021-08-06 , DOI: 10.1007/s00221-021-06187-5
Akira Saito 1, 2, 3 , Kento Nakagawa 4 , Yohei Masugi 2, 5 , Kimitaka Nakazawa 2
Affiliation  

Although voluntary muscle contraction modulates spinal reflex excitability of contracted muscles and other muscles located at other segments within a limb (i.e., intra-limb modulation), to what extent corticospinal pathways are involved in intra-limb modulation of spinal reflex circuits remains unknown. The purpose of the present study was to identify differences in the involvement of corticospinal pathways in intra-limb modulation of spinal reflex circuits among lower-limb muscles during voluntary contractions. Ten young males performed isometric plantar-flexion, dorsi-flexion, knee extension, and knee flexion at 10% of each maximal torque. Electromyographic activity was recorded from soleus, tibialis anterior, vastus lateralis, and biceps femoris muscles. Motor evoked potentials and posterior root-muscle reflexes during rest and isometric contractions were elicited from the lower-limb muscles using transcranial magnetic stimulation and transcutaneous spinal cord stimulation, respectively. Motor evoked potential and posterior root-muscle reflex amplitudes of soleus during knee extension were significantly increased compared to rest. The motor evoked potential amplitude of biceps femoris during dorsi-flexion was significantly increased, whereas the posterior root-muscle reflex amplitude of biceps femoris during dorsi-flexion was significantly decreased compared to rest. These results suggest that corticospinal and spinal reflex excitabilities of soleus are facilitated during knee extension, whereas intra-limb modulation of biceps femoris during dorsi-flexion appeared to be inverse between corticospinal and spinal reflex circuits.



中文翻译:

等长自主收缩期间下肢肌肉诱发的后根肌反射的肢内调节

尽管随意肌肉收缩调节收缩肌肉和位于肢体内其他节段的其他肌肉的脊髓反射兴奋性(即肢体内调制),但皮质脊髓通路在多大程度上参与脊髓反射回路的肢体内调制仍然未知。本研究的目的是确定在自主收缩期间下肢肌肉中脊髓反射回路的肢体内调节中皮质脊髓通路参与的差异。十名年轻男性以每个最大扭矩的 10% 进行等长跖屈、背屈、膝伸和膝屈。从比目鱼肌、胫骨前肌、股外侧肌和股二头肌记录肌电图活动。分别使用经颅磁刺激和经皮脊髓刺激从下肢肌肉引发休息和等长收缩期间的运动诱发电位和后根肌反射。与休息相比,膝关节伸展期间比目鱼肌的运动诱发电位和后根肌反射幅度显着增加。与休息相比,背屈时股二头肌运动诱发电位幅度显着增加,而背屈时股二头肌后根肌反射幅度显着降低。这些结果表明,在膝关节伸展过程中,比目鱼肌的皮质脊髓和脊髓反射兴奋性得到促进,

更新日期:2021-08-09
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