Manjarrez E, Hernández-Paxtián Z, Kohn A F
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla., 14 sur 6301, Col. San Manuel, Apartado Postal 406, C.P. 72570, Puebla, Pue., México.
J Neurophysiol. 2005 Nov;94(5):3199-210. doi: 10.1152/jn.00501.2005. Epub 2005 Jul 13.
Successive stimuli of constant intensity applied to Ia afferents produce spinal monosynaptic reflexes (MSRs) of variable amplitude. We recorded simultaneous MSRs in the left and right L7 (or L6) ventral roots of anesthetized cats. We analyzed the cross-covariance (CCV) between the amplitudes of bilateral MSRs. Long-time series (5 to 8 h) of these bilateral MSRs exhibited transitory changes in their covariations (as measured by the zero-lag peak of their CCV), thus suggesting the existence of certain neural sources contributing to produce these changes. The aim of the present study was to show that spinal centers producing negative spontaneous cord dorsum potentials (nSCDPs) contribute to maintain correlations in the amplitude of bilateral MSRs. After spinal cord transection at the L1 segment, no significant changes were observed in the correlation between the amplitude of bilateral nSCDPs versus the amplitude of bilateral MSRs. However, this correlation, as well as the peak at zero lag in the CCV between bilateral MSRs and the CCV between bilateral nSCDPs, respectively, were abolished after a subsequent longitudinal bisection at the L1-S2 spinal segments. These results suggest that lumbar spinal neurons (bilaterally interconnected) contribute to maintain the synchronous fluctuations of bilateral MSRs.
对Ia传入神经施加强度恒定的连续刺激会产生幅度可变的脊髓单突触反射（MSR）。我们在麻醉猫的左、右L7（或L6）腹根中同时记录MSR。我们分析了双侧MSR幅度之间的互协方差（CCV）。这些双侧MSR的长时间序列（5至8小时）在其协变中表现出短暂变化（通过其CCV的零滞后峰值测量），因此表明存在某些神经源导致了这些变化。本研究的目的是表明产生负性自发脊髓背电位（nSCDP）的脊髓中枢有助于维持双侧MSR幅度的相关性。在L1节段进行脊髓横断后，双侧nSCDP幅度与双侧MSR幅度之间的相关性未观察到显著变化。然而，在随后于L1 - S2脊髓节段进行纵向二分后，这种相关性以及双侧MSR之间CCV的零滞后峰值和双侧nSCDP之间的CCV分别被消除。这些结果表明，腰段脊髓神经元（双侧相互连接）有助于维持双侧MSR的同步波动。
