Thobois S, Jahanshahi M, Pinto S, Frackowiak R, Limousin-Dowsey P
Sobell Department of Motor Neurosciences and Movement Disorders, Institute of Neurology, London, UK.
Neuroimage. 2004 Sep;23(1):1-16. doi: 10.1016/j.neuroimage.2004.04.039.
Functional imaging techniques provide major insights into understanding the pathophysiology, progression, complications, and differential diagnosis of Parkinson's disease (PD). The dopaminergic system has been particularly studied allowing now early, presymptomatic diagnoses, which is of interest for future neuroprotective strategies. The existence of a compensatory hyperactivity of dopa-decarboxylase at disease onset has been recently demonstrated in the nigrostriatal and also extrastriatal dopaminergic pathways. Modification of dopamine receptors expression is observed during PD, but the respective contribution of dopaminergic drugs and the disease process towards these changes is still debated. Abnormalities of cerebral activation are seen and are clearly task-dependent, but the coexistence of hypoactivation in some areas and hyperactivation in others is also now well established. Such hyperactivation may be compensatory but could also reflect an inability to select appropriate motor circuits and inhibit inappropriate ones by PD patients. Interestingly, dopaminergic medications or surgical therapy reverse such abnormalities of brain activation.
功能成像技术为理解帕金森病（PD）的病理生理学、进展、并发症及鉴别诊断提供了重要见解。对多巴胺能系统进行了特别研究，现在能够实现早期、症状前诊断，这对未来的神经保护策略具有重要意义。最近已证实在疾病发作时黑质纹状体及纹状体以外的多巴胺能通路中存在多巴脱羧酶的代偿性活性亢进。在帕金森病过程中可观察到多巴胺受体表达的改变，但多巴胺能药物和疾病进程对这些变化的各自作用仍存在争议。可观察到大脑激活异常，且明显依赖于任务，但现在也已明确在某些区域存在激活不足而在其他区域存在激活过度的共存情况。这种激活过度可能具有代偿作用，但也可能反映帕金森病患者无法选择合适的运动回路并抑制不适当的回路。有趣的是，多巴胺能药物或手术治疗可逆转这种大脑激活异常。
