Lyle Mark A, Wolf Steven L, Cuadra Cristian
Division of Physical Therapy, Department of Rehabilitation Medicine, Center for Physical Therapy and Movement Science, Emory University School of Medicine, Atlanta, GA, USA.
Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Health Care System, Atlanta, GA, USA.
Sci Rep. 2025 Apr 30;15(1):15237. doi: 10.1038/s41598-025-98220-8.
Heteronymous reflexes from quadriceps can increase and/or decrease soleus activity; yet few studies have examined factors influencing reflex strength. This study examined the independent influence of limb loading, posture, and task context on heteronymous feedback from quadriceps onto soleus. The influence of limb loading and posture was determined by comparing femoral nerve elicited heteronymous excitation and inhibition of soleus in a semi-recumbent position with and without 50% body weight limb loading and while standing with back support (n = 16). Task context was examined by comparing heteronymous reflex magnitudes while standing with back support to maintaining an unsupported squat posture which requires tonic soleus activity to maintain the posture (n = 12). Heteronymous inhibition decreased by 20% with limb loading in both semi-recumbent and standing postures, while excitation remained unchanged suggesting that limb loading, rather than postural orientation, independently modulates heteronymous inhibition. Inhibition decreased by 50% and excitation by 90% when maintaining the squat posture compared to supported standing. The pronounced suppression of both excitation and inhibition during the squat is considered a task-appropriate reflex modulation that aids in maintaining the posture. The results of this study highlight an important modulatory influence of limb loading afferents and task context on heteronymous reflex circuits.
来自股四头肌的异侧反射可增强和/或减弱比目鱼肌的活动；然而，很少有研究探讨影响反射强度的因素。本研究考察了肢体负荷、姿势和任务背景对股四头肌至比目鱼肌异侧反馈的独立影响。通过比较在半卧位有和没有50%体重肢体负荷时以及在有背部支撑站立时股神经引发的比目鱼肌异侧兴奋和抑制，来确定肢体负荷和姿势的影响（n = 16）。通过比较在有背部支撑站立与维持无支撑深蹲姿势（这需要比目鱼肌持续活动以维持姿势）时的异侧反射幅度，来考察任务背景（n = 12）。在半卧位和站立姿势下，肢体负荷均使异侧抑制降低20%，而异侧兴奋保持不变，这表明是肢体负荷而非姿势方向独立调节异侧抑制。与有支撑站立相比，维持深蹲姿势时抑制降低50%，兴奋降低90%。深蹲过程中兴奋和抑制均明显受到抑制，这被认为是一种有助于维持姿势的与任务相适应的反射调节。本研究结果突出了肢体负荷传入信号和任务背景对异侧反射回路的重要调节作用。
