Ackermann H, Konczak J, Hertrich I
Department of Neurology, University of Tübingen, Germany.
Brain Lang. 1997 Feb 1;56(2):312-9. doi: 10.1006/brln.1997.1851.
Recent clinical data indicate that internal cueing mechanisms required for the triggering of movement sequences are impaired in Parkinson's disease (PD). Nevertheless, most PD subjects produce maximal syllable repetition rates similar to those observed in healthy control individuals during oral diadochokinesis tasks. There is some evidence that tremor oscillations may pace repetitive movements in Parkinsonians giving rise to hastening phenomena. Conceivably, the performance of PD patients in syllable repetition tasks thus reflects a specific timing deficit, i.e., articulatory hastening. It is the aim of the present study to investigate the contribution of speech hastening to oral diadochokinesis in the presence of internal and external cues. By means of an optoelectric movement analysis system, the displacements of the lips during repetitions of the syllable /pa/ were recorded in two akinetic-rigid PD individuals. Subjects were asked to synchronize labial diadochokinesis to sequences of periodic acoustic stimuli (2.5-6 Hz). One of the PD patients showed speech hastening, i.e., he produced repetitions of 8 to 9 Hz whenever stimulus frequencies exceeded 4 Hz. The other Parkinsonian adequately matched the stimulus frequencies required. However, she achieved a higher diadochokinesis rate in the matching task than under the instruction to repeat "as fast as possible." Thus, the presence of an external cue improved performance. In conclusion, our data indicate two deficits of the temporal control of repetitive articulatory gestures in PD: speech hastening and impaired self-paced sequencing. These two pathomechanisms may allow to reconcile the controversial findings on oral diadochokinesis in PD reported so far.
近期临床数据表明，帕金森病（PD）患者触发运动序列所需的内部提示机制受损。然而，在口腔轮替运动任务中，大多数PD患者产生的最大音节重复率与健康对照个体相似。有证据表明，震颤振荡可能为帕金森病患者的重复性运动设定节奏，从而导致加速现象。可以想象，PD患者在音节重复任务中的表现反映了一种特定的时间控制缺陷，即发音加速。本研究的目的是在存在内部和外部提示的情况下，研究言语加速对口腔轮替运动的影响。通过光电运动分析系统，记录了两名运动不能-强直型PD患者在重复音节/pa/时嘴唇的位移。受试者被要求使唇部轮替运动与周期性听觉刺激序列（2.5-6Hz）同步。其中一名PD患者表现出言语加速，即每当刺激频率超过4Hz时，他会以8至9Hz的频率重复。另一名帕金森病患者能够充分匹配所需的刺激频率。然而，她在匹配任务中的轮替运动速率高于在“尽可能快地”重复指令下的速率。因此，外部提示的存在提高了表现。总之，我们的数据表明PD患者在重复性发音手势的时间控制方面存在两个缺陷：言语加速和自我节奏序列受损。这两种病理机制可能有助于调和迄今为止关于PD患者口腔轮替运动的有争议的研究结果。
