Butler John S, Fearon Conor, Killane Isabelle, Waechter Saskia M, Reilly Richard B, Lynch Timothy
Trinity Centre for Bioengineering, Trinity College, The University of Dublin, Dublin 2, Ireland; School of Engineering, Trinity College, The University of Dublin, Dublin 2, Ireland; School of Mathematical Sciences, Dublin Institute of Technology, Kevin Street, Dublin, Ireland.
Trinity Centre for Bioengineering, Trinity College, The University of Dublin, Dublin 2, Ireland; School of Engineering, Trinity College, The University of Dublin, Dublin 2, Ireland; Dublin Neurological Institute at the Mater Misericordiae University Hospital, Dublin 7, Ireland.
Clin Neurophysiol. 2017 Mar;128(3):463-471. doi: 10.1016/j.clinph.2016.12.019. Epub 2016 Dec 28.
Freezing of gait (FOG) is a brief, episodic phenomenon affecting over half of people with Parkinson's disease (PD) and leads to significant morbidity. The pathophysiology of FOG remains poorly understood but is associated with deficits in cognitive function and motor preparation.
We studied 20 people with PD (10 with FOG, 10 without FOG) and performed a timed response target detection task while electroencephalographic data were acquired. We analysed the data to detect and examine cortical markers of cognitive decision making (P3b or centroparietal positivity, CPP) and motor readiness potential. We analysed current source density (CSD) to increase spatial resolution and allow identification of distinct signals.
There was no difference in the P3b/CPP response between people with PD with and without FOG, suggesting equivalent cognitive processing with respect to decision-making. However, the FOG group had significant difference with an earlier onset and larger amplitude of the lateralized readiness potential. Furthermore, the amplitude of the lateralised readiness potential correlated strongly with total Frontal Assessment Battery score.
The difference in lateralized readiness potentials may reflect excessive recruitment of lateral premotor areas to compensate for dysfunction of the supplementary motor area and resultant loss of automatic motor control. This early, excessive recruitment of frontal networks occurs in spite of equivalent motor scores and reaction times between groups.
The saturation of frontal processing mechanisms could help explain deficits in attentional set-shifting, dual-tasking and response inhibition which are frequently reported in FOG.
冻结步态（FOG）是一种短暂的发作性现象，影响超过半数的帕金森病（PD）患者，并导致严重的发病率。FOG的病理生理学仍知之甚少，但与认知功能和运动准备缺陷有关。
我们研究了20名PD患者（10名有FOG，10名无FOG），并在采集脑电图数据的同时进行了定时反应目标检测任务。我们分析数据以检测和检查认知决策的皮质标记物（P3b或中央顶叶正波，CPP）和运动准备电位。我们分析电流源密度（CSD）以提高空间分辨率并识别不同信号。
有FOG和无FOG的PD患者之间的P3b/CPP反应没有差异，表明在决策方面认知处理相当。然而，FOG组在侧化准备电位的起始时间更早和幅度更大方面有显著差异。此外，侧化准备电位的幅度与额叶评估量表总分密切相关。
侧化准备电位的差异可能反映了外侧运动前区过度募集以补偿辅助运动区功能障碍以及由此导致的自动运动控制丧失。尽管两组之间的运动评分和反应时间相当，但额叶网络的这种早期过度募集仍会发生。
额叶处理机制的饱和有助于解释FOG中经常报告的注意力转换、双任务和反应抑制缺陷。
