DEPOLARIZATION OF CENTRAL TERMINALS OF GROUP I AFFERENT FIBRES FROM MUSCLE
DEPOLARIZATION OF CENTRAL TERMINALS OF GROUP I AFFERENT FIBRES FROM MUSCLE
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DOI：
10.1113/jphysiol.1962.sp006835
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发表时间：
1962-01-01
影响因子：
5.5
通讯作者：
MAGNI, F
中科院分区：
文献类型：
--
作者：
ECCLES, JC;WILLIS, WD;MAGNI, F
猫后肢屈肌的神经中的I组传入截击在产生来自所有类型肌肉的I组传入纤维的延长去极化中是非常有效的。这种初级传入去极化（PAD）不仅通过来自脊髓中Ia和Ib传入纤维的细胞内记录和背根电位来揭示，而且还通过这些纤维的兴奋性增加和脊髓中产生的场电位来展示。I组截击在伸肌的神经上对Ia组传入的去极化作用很小或没有去极化作用，但对许多Ib组传入有效。此外，第二组截击在屈肌和伸肌的神经引起除第一组肌肉的传入纤维的去极化。PAD总是具有缓慢的时程潜伏期4-6毫秒; 15-20毫秒到达峰值;并且总持续时间为100-300毫秒。据推测，PAD是由运动神经元核和中间核的初级传入纤维分支上的长时间突触去极化作用产生的，并且去极化从那里电紧张性地沿着纤维传播，甚至进入背根。在产生PAD的中枢通路上存在空间和时间的总和;因此假定它通过突触中继。长的中枢潜伏期为几个神经元间的传递提供了时间。PAD的强直后增强在条件或接收传入神经的延长强直后观察约60秒。它的结论是，PAD的第一组传入纤维的原因是大多数的延长场电位的第一组传入凌空从屈肌产生在脊髓中，即该领域是面向腹外侧负性和背内侧正性。它也可以得出结论，PAD提供了一个完整的解释突触前抑制所产生的I组传入截击从肌肉。
Group I afferent volleys in the nerves to flexor muscles of the cat hind limb are very effective in producing a prolonged depolarization of the Group I afferent fibres from all types of muscle. This primary afferent depolarization (PAD) is revealed not only by intracellular recording from the Ia and Ib afferent fibres in the cord and by the dorsal root potential, but it is also exhibited by the increased excitability of these fibres and by the field potential which is produced in the spinal cord. Group I volleys in the nerves to extensor muscles have little or no depolarizing action on Group Ia afferents, but are effective on many Group Ib afferents. Furthermore, Group II volleys in the nerves to both flexor and extensor muscles cause depolarization of afferent fibres other than the Group I of muscle. The PAD always has a slow time course latency 4-6 msec; 15-20 msec to summit; and a total duration of 100-300 msec. It is postulated that the PAD is produced by a prolonged synaptic depolarizing action on branches of primary afferent fibres in the motoneur-onal and intermediate nuclei, and that the depolarization spreads thence electrotonically along the fibres even into the dorsal roots. There is both spatial and temporal summation on the central pathway producing the PAD; hence it is postulated to pass through synaptic relays. The long central latency gives time for several interneuronal relays. Post-tetanic potentiation of the PAD is observed for about 60 sec after prolonged tetanization either of the conditioning or of the receiving afferent nerve. It is concluded that the PAD of Group I afferent fibres is the cause of most of the prolonged field potentials which Group I afferent volleys from flexor muscles generate in the spinal cord, i.e. of the field that is oriented with ventrolateral negativity and dorsomedial positivity. It is also concluded that the PAD provides a complete explanation of the presynaptic inhibition that is produced by Group I afferent volleys from muscle.