Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, VIC, Australia.
Neuroscience. 2011 Sep 29;192:382-90. doi: 10.1016/j.neuroscience.2011.06.057. Epub 2011 Jun 25.
Friedreich ataxia (FRDA) is the most common of the inherited ataxias. We have suggested that people with FRDA may have impairment in cognitive and/or psychomotor capacity either due to disturbance of projections of the cerebellum to the cortex, direct cortical pathology or perhaps both. To further explore this possibility, we used a movement task incorporating Fitts' Law, a robust description of the relationship between movement time and accuracy in goal-directed aiming movements. By manipulating task difficulty, according to target size and distance, we were able to quantify processes related to motor planning in 10 individuals with FRDA and 10 matched control participants. Compared to control participants, people with FRDA were significantly disadvantaged in terms of movement time to targets with an increasing index of difficulty. Successful completion of this task requires both preplanning of movement and online error detection and correction. The cerebellum and its connections to the frontal cortex via cerebro-ponto-cerebello-thalamo-cerebral loops are fundamental to both processes. These results lend further support to our contention that in FRDA these loops are impaired, reflecting a failure to access prefrontal/anterior regions necessary for effective management of preplanning of movement and online error correction.
弗里德赖希共济失调（FRDA）是最常见的遗传性共济失调。我们曾提出，FRDA 患者可能存在认知和/或精神运动能力障碍，这可能是由于小脑向皮层的投射受到干扰、直接皮层病变，或者两者兼而有之。为了进一步探讨这种可能性，我们使用了一项包含菲茨定律的运动任务，该定律是对目标导向瞄准运动中运动时间和准确性之间关系的强有力描述。通过根据目标大小和距离来调整任务难度，我们能够量化与运动计划相关的过程，涉及 10 名 FRDA 患者和 10 名匹配的对照组参与者。与对照组参与者相比，FRDA 患者在完成难度逐渐增加的目标的运动时间方面明显处于劣势。完成这项任务需要运动的预先规划和在线错误检测和纠正。小脑及其通过脑桥小脑脚核丘脑皮质环路与前额叶皮质的连接对于这两个过程都是至关重要的。这些结果进一步支持了我们的观点，即在 FRDA 中，这些环路受到了损害，反映出无法访问前额叶/前部区域，而这些区域对于有效管理运动的预先规划和在线错误纠正至关重要。
