Department of Neurology, Duke University School of Medicine, 40 Medicine Circle Box 3824, Durham, NC, 27710, USA.
Department of Basic and Clinical Sciences, University of Nicosia Medical School, 21 Ilia Papakyriakou, Block C, Rm 202, 1700, Nicosia, Cyprus.
Exp Brain Res. 2024 Oct;242(10):2309-2327. doi: 10.1007/s00221-024-06906-8. Epub 2024 Aug 6.
Plantarflexors provide propulsion during walking and receive input from both corticospinal and corticoreticulospinal tracts, which exhibit some frequency-specificity that allows potential differentiation of each tract's descending drive. Given that stroke may differentially affect each tract and impair the function of plantarflexors during walking; here, we examined this frequency-specificity and its relation to walking-specific measures during post-stroke walking. Fourteen individuals with chronic stroke walked on an instrumented treadmill at self-selected and fast walking speed (SSWS and FWS, respectively) while surface electromyography (sEMG) from soleus (SOL), lateral gastrocnemius (LG), and medial gastrocnemius (MG) and ground reaction forces (GRF) were collected. We calculated the intermuscular coherences (IMC; alpha, beta, and low-gamma bands between SOL-LG, SOL-MG, LG-MG) and propulsive impulse using sEMG and GRF, respectively. We examined the interlimb and intralimb IMC comparisons and their relationships with propulsive impulse and walking speed. Interlimb IMC comparisons revealed that beta LG-MG (SSWS) and low-gamma SOL-LG (FWS) IMCs were degraded on the paretic side. Intralimb IMC comparisons revealed that only alpha IMCs (both speeds) exhibited a statistically significant difference to random coherence. Further, alpha LG-MG IMC was positively correlated with propulsive impulse in the paretic limb (SSWS). Alpha and beta/low-gamma bands may have a differential functional role, which may be related to the frequency-specificity of the underlying descending drives. The persistence of alpha band in plantarflexors and its strong positive relationship with propulsive impulse suggests relative alteration of corticoreticulospinal tract after stroke. These findings imply the presence of frequency-specific descending drives to walking-specific muscles in chronic stroke.
跖屈肌在行走时提供推进力，并接收来自皮质脊髓和皮质网状脊髓束的输入，这些输入具有一定的频率特异性，允许潜在地区分每个束的下行驱动。鉴于中风可能会对每个束产生不同的影响，并在行走时损害跖屈肌的功能；在这里，我们研究了这种频率特异性及其与中风后行走时特定行走测量的关系。14 名慢性中风患者在仪器化跑步机上以自我选择的速度（SSWS）和快速行走速度（FWS）行走，同时采集比目鱼肌（SOL）、外侧腓肠肌（LG）和内侧腓肠肌（MG）的表面肌电图（sEMG）和地面反作用力（GRF）。我们分别使用 sEMG 和 GRF 计算了肌肉间相干性（IMC；SOL-LG、SOL-MG、LG-MG 之间的 alpha、beta 和低 gamma 波段）和推进冲量。我们检查了肢体间和肢体内 IMC 的比较及其与推进冲量和行走速度的关系。肢体间 IMC 的比较表明，beta LG-MG（SSWS）和低 gamma SOL-LG（FWS）IMC 在患侧减弱。肢体内 IMC 的比较表明，只有 alpha IMC（两种速度）与随机相干性存在统计学上的显著差异。此外，alpha LG-MG IMC 与患侧的推进冲量呈正相关（SSWS）。alpha 和 beta/low-gamma 波段可能具有不同的功能作用，这可能与潜在的下行驱动频率特异性有关。alpha 波段在跖屈肌中的持续存在及其与推进冲量的强烈正相关表明皮质网状脊髓束在中风后发生了相对改变。这些发现表明慢性中风中存在与行走特定肌肉的频率特异性下行驱动。
