Baev K V, Esipenko V B, Shimansky Y P
Department of Physiology of the Spinal Cord, A. A. Bogomoletz Institute of Physiology, Academy of Sciences of the Ukrainian S.S.R., Kiev.
Neuroscience. 1991;40(1):239-56. doi: 10.1016/0306-4522(91)90187-s.
Systematic quantitative analysis of changes in the spinal scratching generator motor activity evoked by tonic and phasic peripheral afferent signals during "fictitious" scratching was carried out in the cat. Correlations between the kinematics of hindlimb scratching movement, sensory inflow, and primary afferent depolarization were investigated. Reliable correlations between the parameters of generator motor activity during fictitious scratching were revealed: they depended on tonic peripheral afferent inflow. The functional role of these dependencies consists of providing stability for aiming the hindlimb to the itch site. It was shown that scratching generator reaction to a phasic sensory signal depended significantly on afferent input, signal intensity, and its arrival phase in the cycle of motor activity. Phase correction of "scratching" rhythm was performed by inhibition of the current stage of "scratching" cycle, the inhibition magnitude depending on the intensity of a sensory signal run along high threshold afferent fibers. The moments in the scratching cycle, in which the afferent signal caused no rearrangement in scratching generator activity, were discovered for all investigated afferent inputs. These moments corresponded to the transitions from one scratching cycle phase to another. Integral afferent activity was distributed unevenly in the cycle during real scratching. The main part of it was observed just in that scratching cycle part which included the above mentioned no rearrangement phase points. The data obtained allowed us to conclude that the scratching generator should be considered as a working program for the motor optimal control system containing the intrinsic model of the controlled object dynamics (e.g. hindlimb scratching movement dynamics), which produces an inner analog of peripheral flow. This inner flow interacts with peripheral afferent inflow just as one of the latter components. Centrally originated modulation of primary afferent depolarization is a result of affecting the depolarization generating system by this inner "sensory" activity. It is the model, with the aid of which the generator can work after deafferentation. The functional organization of a central pattern generator is considered.
在猫身上进行了系统的定量分析，研究了在“虚拟”抓挠过程中，由紧张性和阶段性外周传入信号诱发的脊髓抓挠发生器运动活动的变化。研究了后肢抓挠运动的运动学、感觉传入和初级传入去极化之间的相关性。揭示了虚拟抓挠过程中发生器运动活动参数之间的可靠相关性：它们取决于紧张性外周传入输入。这些依赖性的功能作用在于为后肢指向瘙痒部位提供稳定性。结果表明，抓挠发生器对阶段性感觉信号的反应显著取决于传入输入、信号强度及其在运动活动周期中的到达阶段。“抓挠”节律的相位校正通过抑制“抓挠”周期的当前阶段来实现，抑制幅度取决于沿高阈值传入纤维传导的感觉信号的强度。对于所有研究的传入输入，都发现了抓挠周期中传入信号不会引起抓挠发生器活动重新排列的时刻。这些时刻对应于从一个抓挠周期阶段到另一个阶段的过渡。在实际抓挠过程中，整体传入活动在周期中分布不均匀。其主要部分恰好在包含上述无重新排列阶段点的抓挠周期部分中观察到。所获得的数据使我们能够得出结论，抓挠发生器应被视为运动最优控制系统的一个工作程序，该系统包含受控对象动力学的内在模型（例如后肢抓挠运动动力学），它产生外周信息流的内部模拟。这种内部流与外周传入流相互作用，就如同外周传入流的一个组成部分。初级传入去极化的中枢起源调制是这种内部“感觉”活动影响去极化产生系统的结果。正是这个模型，借助它发生器在去传入后仍能工作。文中考虑了中枢模式发生器的功能组织。
