Pivik R T, Bylsma F
Department of Psychiatry, University of Ottawa, Ont., Canada.
Int J Psychophysiol. 1990 Jul;9(1):85-95. doi: 10.1016/0167-8760(90)90010-b.
H-reflex recovery functions and homosynaptic depression curves were studied in unmedicated hyperkinetic and control children in the presence and absence of the Jendrassik manoeuvre. The Jendrassik manoeuvre failed to affect recovery function reflex amplitude across or within groups, but reflex amplitude was augmented in the homosynaptic depression procedure for hyperkinetic children who failed to show recovery function facilitation. The absence of Jendrassik-associated reflex facilitation in children during the recovery function and during selective homosynaptic depression rates may reflect developmental influences on processes underlying this phenomenon. However, reflex augmentation in non-facilitating hyperkinetic subjects suggests that these processes are present in children and can be revealed under conditions of decreased motoneuronal excitability. These findings suggest that reduced gamma-efferent drive may contribute to decreased motoneuronal excitability observed in hyperkinetic children, but the possible role of other Jendrassik-activated influences, such as coactivation of alpha and gamma motoneurons or selective activation of alpha motoneurons by processes independent of increased gamma-efferent drive, cannot be excluded.
在有无詹德拉西克动作的情况下，对未用药的多动症儿童和对照儿童的H反射恢复功能及同突触抑制曲线进行了研究。詹德拉西克动作未能影响各组间或组内的恢复功能反射幅度，但在未能表现出恢复功能易化的多动症儿童的同突触抑制过程中，反射幅度增大。在恢复功能期间以及选择性同突触抑制率期间，儿童缺乏与詹德拉西克相关的反射易化现象，这可能反映了发育对该现象潜在过程的影响。然而，在无易化的多动症受试者中反射增强表明，这些过程在儿童中存在，并且在运动神经元兴奋性降低的条件下可以显现出来。这些发现表明，γ传出驱动降低可能导致多动症儿童运动神经元兴奋性降低，但不能排除其他詹德拉西克激活影响的可能作用，如α和γ运动神经元的共同激活或由独立于γ传出驱动增加的过程对α运动神经元的选择性激活。
