RESPIRATORY INTERNEURONES IN THE THORACIC SPINAL-CORD OF THE CAT
RESPIRATORY INTERNEURONES IN THE THORACIC SPINAL-CORD OF THE CAT
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DOI：
10.1113/jphysiol.1988.sp016913
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发表时间：
1988-01-01
影响因子：
5.5
通讯作者：
WESTGAARD, RH
中科院分区：
文献类型：
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作者：
KIRKWOOD, PA;MUNSON, JB;WESTGAARD, RH
1.麻醉瘫痪猫胸段前角(T_3~T_9)记录到自发放电的神经元，其活动与中枢呼吸周期同步。2.在310个神经元中，46个通过逆行激活或棘波触发平均法确定为运动神经元，54个通过其他脊髓节段的逆行激活确定为神经元间神经元，90个根据运动神经元的位置或放电频率间接识别为神经元间神经元。3.根据最大放电率的次数将单位分为吸气型(%)、呼气型(25%)和吸气型(7%)。其余4%的单位的排放物要么强烈锁定在呼吸泵循环中，要么不属于其他类别。除了一个，所有的运动神经元都被归类为吸气或呼气。4.根据吸气和呼气单位在呼吸周期中开始放电的时间，将其进一步划分为早、晚或强直。与吸气组和呼气组的运动神经元相比，神经元间神经元(既有阳性的也有间接的)包括更多的早期和紧张性类别以及更多的快放电单位。5.运动神经元的位置与肋间和软骨间运动核的已知位置相对应，包括吸气和呼气种群的明显分离。无论是神经元间神经元还是不明单位的位置都没有根据它们的放电模式进行分离。这些神经元集中在腹角的内侧半部，通常比运动神经元的位置更背侧，尽管它们的位置与这一组有相当大的重叠。6.阳性神经元的轴突位于尾侧1~5个节段，大部分位于对侧，但未追踪到它们的终末。一些轴突通过微刺激定位于腹侧或腹内侧白质。传导速度的范围很广，8~100m/S，平均53m/S。7.初步计算表明，呼吸性胸椎间神经元的数量可能是呼吸球脊髓神经元的近10倍。讨论了这些计算和其他结果对神经元间可能的生理作用的影响。
1. The discharges of spontaneously firing neurones, whose activity was modulated in phase with the central respiratory cycle, were recorded in the thoracic ventral horn (T3-T9) of anaesthetized, paralyzed cats. 2. Out of 310 neurones, forty-six were positively identified as motoneurones by antidromic activation or spike-triggered averaging, fifty-four were positively identified as interneurones by antidromic activation from other spinal cord segments and ninety were indirectly identified as interneurones by virtue of their positions or firing rates as compared to the motoneurones. 3. Units were classified as inspiratory (64%), expiratory (25%) or post-inspiratory (7%) according to the times of their maximum firing rates. The remaining 4% consisted of units whose discharges were either strongly locked to the respiratory pump cycle or did not fit into the other categories. All but one of the motoneurones were classified as inspiratory or expiratory. 4. Inspiratory and expiratory units were further classified as early, late or tonic according to the starting times of their discharges in the respiratory cycle. The interneurones (both positively and indirectly identified) included more of the early and tonic categories and more fast-firing units than did the motoneurones in both the inspiratory and expiratory groups. 5. The locations of the motoneurones corresponded to the known positions of the intercostal and interchondral motor nuclei, including clear segregation of inspiratory and expiratory populations. The locations of neither the interneurones nor the unidentified units were segregated according to their firing patterns. These neurones were concentrated in the medial half of the ventral horn and were found generally more dorsally than the positions of the motoneurones, though their positions overlapped considerably with this group. 6. The axons of the positively identified interneurones were identified from one to five segments caudally and mostly contralaterally, but were not traced to their terminations. Some axons were located by microstimulation and found to run in the ventral or ventromedial white matter. Conduction velocities covered a wide range, 8 to around 100 m/s, mean 53 m/s. 7. Preliminary calculations indicate that there may be almost 10 times more respiratory thoracic interneurones as respiratory bulbospinal neurones. The implications of these calculations and the other results for the likely physiological roles of the interneurones are discussed.