Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, BC, Canada.
Department of Psychology, University of Toronto, Toronto, ON, Canada.
Neuroimage Clin. 2019;23:101922. doi: 10.1016/j.nicl.2019.101922. Epub 2019 Jul 2.
Apathy is a common non-motor symptom of Parkinson's disease (PD) that is difficult to quantify and poorly understood. Some studies have used incentivized motor tasks to assess apathy, as the condition is often associated with a reduction in motivated behavior. Normally event-related desynchronization, a reduction of power in specific frequency bands, is observed in the motor cortex during the peri-movement period. Also, alpha (8-12 Hz) and theta (4-7 Hz) oscillations are sensitive to rewards that are closely related to motivational states however these oscillations have not been widely investigated in relation to apathy in PD. Using EEG recordings, we investigated the neural oscillatory characteristics of apathy in PD during an incentivized motor task with interleaved rest periods. Apathetic and non-apathetic PD subjects on dopaminergic medication and healthy control subjects were instructed to squeeze a hand grip device for a monetary reward proportional to the subject's grip force and the monetary value attributed to that trial. Apathetic PD subjects exhibited higher alpha and theta powers in the pre-trial baseline rest period compared to non-apathetic PD subjects and healthy subjects. Further, we found that both resting power and relative power in alpha and theta bands during incentivized movement predicted PD subjects' apathy scores. Our results suggest that apathetic PD patients may need to overcome greater baseline alpha and theta oscillatory activity in order to facilitate incentivized movement. Clinically, resting alpha and theta power as well as alpha and theta event-related desynchronization during movement may serve as potential neural markers for apathy severity in PD.
冷漠是帕金森病（PD）的一种常见非运动症状，难以量化且了解甚少。一些研究使用激励运动任务来评估冷漠，因为这种情况通常与动机行为减少有关。正常情况下，在运动皮层中，在运动前期间会观察到事件相关去同步化，即特定频带中的功率降低。此外，α（8-12 Hz）和θ（4-7 Hz）振荡对与动机状态密切相关的奖励敏感，但是这些振荡在与 PD 中的冷漠有关的方面尚未得到广泛研究。使用 EEG 记录，我们在带有间歇休息期的激励运动任务中研究了 PD 中冷漠的神经振荡特征。接受多巴胺能药物治疗的冷漠和非冷漠 PD 患者和健康对照者被指示紧握手部握持装置，以获得与受试者的握持力和该试验的货币价值成比例的货币奖励。与非冷漠 PD 患者和健康受试者相比，冷漠 PD 患者在试验前基线休息期显示出更高的α和θ功率。此外，我们发现，激励运动期间的静息功率和α和θ波段的相对功率均可以预测 PD 患者的冷漠评分。我们的结果表明，冷漠的 PD 患者可能需要克服更大的基线α和θ振荡活动，以促进激励运动。临床上，静止时的α和θ功率以及运动时的α和θ事件相关去同步化可以作为 PD 中冷漠严重程度的潜在神经标志物。
