Development of coritcospinal effects on forelimb motor control.

本实验研究了皮质脊髓束在猫和幼年大鼠脊髓运动中枢的作用和机制。(1)利用前肢肌电记录和前肢运动神经元细胞内记录，研究了电刺激去大脑猫锥体束的作用。肌肉活动仅在屈肌中被诱发，并且在运动过程中的屈肌阶段最为显著。皮质脊髓束的兴奋效应将以双突触的方式传递到运动神经元。此外，在脊髓部分损毁的实验中，我们提示支配远端和近端肌肉的运动神经元传递皮质脊髓效应的途径不同。(2)采用幼年大鼠颈脊髓切片制片，对皮质脊髓纤维向运动神经元的突触传递进行了药理学研究。我们发现，在切片制备过程中，可以选择性地刺激背索中的皮质脊髓束纤维。该通路由NMDA受体和非NMDA受体共同传递，并受甘氨酸能抑制作用的调节。(3)取新生大鼠大脑皮层或胸段脊髓，分别移植胚胎组织。移植后1~4个月，通过记录脊髓移植标本中每只足的足印，获得运动模式改变的初步结果。

We studied on the role and mechanism of the corticospinal tract in the spinal motor center in the cat and immature rat.(1) We examined the effect of stimulation of the pyramidal tract using electromyographic recordings from forelimb muscles and intracellular recordings from their innervating motoneurones in the decerebrated cat. Muscle activities were evoked exclusively in the flexor muscle and they were most prominent in the flexor phase during locomotion. The excitatory effect from the corticospinal tract would be transmitted disynaptically to the motoneurone. Furthermore, we suggested in the experiment of the partial lesion of the spinal cord that the pathway conveying the corticospinal effect was different in motoneurones innervating distant and proximal muscles.(2) We examined pharmacologically on the synaptic transmission from corticospinal fibers to motoneurones using the slice preparation of the cervical spinal cord of the immature rat. We revealed that the corticospinal tract fibers in the dorsal funiculus could be selectively stimulated in the slice preparation. The pathway was transmitted by both NMDA and nonNMDA receptors and modulated by glycinergic inhibition.(3) The cerebral cortex or the thoracic spinal cord were removed from the newborn rat, and the respective tissue from the embryo was transplanted. One to four months after the transplant, we obtained the preliminary result of changes in the locomotor pattern which was analyzed by recordings of the foot print from each foot in the spinal cord transplanted preparation.