McIntyre A K, Proske U, Rawson J A
J Physiol. 1984 Sep;354:395-406. doi: 10.1113/jphysiol.1984.sp015383.
In cats anaesthetized with chloralose, evidence has been sought for the projection of information from tendon organs to the sensory receiving areas of the cerebral cortex. Selective stimulation of afferent fibres from tendon organs has been achieved by raising the threshold to electrical stimulation of the fibres from primary endings of muscle spindles. The method uses longitudinal vibration at 200-250 Hz to elicit, over a period of 20 min, one impulse for each excursion of the vibrator from all of the spindles in the test muscle, soleus or medial gastrocnemius. The accumulated post-spike positivities following passage of the impulses are thought to be responsible for the rise in threshold. Segmental monosynaptic reflex testing after a bout of vibration was used to confirm that the residual Group I volley no longer contained impulses from muscle spindles. The volley in response to stimulating the nerve of the test muscle was timed to facilitate the monosynaptic reflex of a synergist. Before vibration 5- to 10-fold facilitation of reflex amplitude could be produced; however, after vibration, if all the spindle primary endings had been effectively engaged by the stimulus, no detectable facilitation remained. This test was found to be sensitive and reproducible. An afferent volley containing only activity of tendon organ afferents evoked small-amplitude potentials from the post-sigmoid gyrus of the contralateral pericruciate cortex. The field was highly localized and lay caudal to the main receiving area for activity from the sural nerve and from afferents of hip flexor muscles. Recordings with tungsten micro-electrodes revealed that the surface-evoked activity took origin in cellular discharges in the internal pyramidal layer of area 3a. Recent psychophysical experiments have provided evidence for a sense of muscle tension, as distinct from a sense of effort, and the tendon organ has been suggested as the likely receptor of origin. Our electrophysiological observations now provide a firm experimental basis for such a proposal.
在用氯醛糖麻醉的猫身上，人们一直在寻找从腱器官向大脑皮层感觉接收区投射信息的证据。通过提高对来自肌梭初级末梢纤维的电刺激阈值，实现了对腱器官传入纤维的选择性刺激。该方法利用200 - 250赫兹的纵向振动，在20分钟内，使测试肌肉（比目鱼肌或内侧腓肠肌）中所有肌梭的振动器每次摆动引发一个冲动。冲动通过后积累的锋电位后正电位被认为是阈值升高的原因。一阵振动后进行节段性单突触反射测试，以确认剩余的I组群峰电位不再包含来自肌梭的冲动。对测试肌肉神经刺激的群峰电位进行计时，以促进协同肌的单突触反射。振动前，反射幅度可提高5至10倍；然而，振动后，如果所有肌梭初级末梢都被刺激有效激活，则不再有可检测到的促进作用。发现该测试灵敏且可重复。仅包含腱器官传入活动的传入群峰电位在对侧十字周皮层乙状回后引发小幅度电位。该区域高度局限，位于腓肠神经和髋屈肌传入活动主要接收区的尾侧。钨微电极记录显示，表面诱发活动起源于3a区锥体细胞层的细胞放电。最近的心理物理学实验提供了证据，证明存在一种与用力感不同的肌肉紧张感，并且有人提出腱器官可能是其起源感受器。我们的电生理观察现在为这一观点提供了坚实的实验基础。
