Casartelli Luca, Federici Alessandra, Cesareo Ambra, Biffi Emilia, Valtorta Giulia, Molteni Massimo, Ronconi Luca, Borgatti Renato
Child Psychopathology Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy;
Child Psychopathology Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
J Neurophysiol. 2017 Apr 1;117(4):1474-1482. doi: 10.1152/jn.00771.2016. Epub 2017 Jan 11.
Motor planning is not a monolithic process, and distinct stages of motor planning are responsible for encoding different levels of abstractness. However, how these distinct components are mapped into different neural substrates remains an open question. We studied one of these high-level motor planning components, defined as second-order motor planning, in a patient (R.G.) with an extremely rare case of cerebellar agenesis but without any other cortical malformations. Second-order motor planning dictates that when two acts must be performed sequentially, planning of the second act can influence execution of the first. We used an optoelectronic system for kinematic analysis to compare R.G.'s performance with age-matched controls in a second-order motor planning task. The first act was to reach for an object, and the second was to place it into a small or large container. Our results showed that despite the expected difficulties in fine-motor skills, second-order motor planning (i.e., the ability to modulate the first act as a function of the nature of the second act) was preserved even in the patient with congenital absence of the cerebellum. These results open new intriguing speculations about the role of the cerebellum in motor planning abilities. Although prudence is imperative when suggesting conclusions made on the basis of single-case findings, this evidence suggests fascinating hypotheses about the neural circuits that support distinct stages of the motor planning hierarchy, and regarding the functional role of second-order motor planning in motor cognition and its potential dysfunction in autism. Traditionally, the cerebellum was considered essential for motor planning. By studying an extremely rare patient with cerebellar agenesis and a group of neurotypical controls, we found that high stages of the motor planning hierarchy can be preserved even in this patient with congenital absence of the cerebellum. Our results provide interesting insights that shed light on the neural circuits supporting distinct levels of motor planning. Furthermore, the results are intriguing because of their potential clinical implications in autism.
运动规划不是一个单一的过程，不同阶段的运动规划负责编码不同程度的抽象信息。然而，这些不同的组成部分如何映射到不同的神经基质上仍是一个悬而未决的问题。我们研究了其中一个高级运动规划组件，即二阶运动规划，该研究对象是一名患有极为罕见的小脑发育不全但无其他皮质畸形的患者（R.G.）。二阶运动规划表明，当必须依次执行两个动作时，第二个动作的规划会影响第一个动作的执行。我们使用光电系统进行运动学分析，以比较R.G.在二阶运动规划任务中与年龄匹配的对照组的表现。第一个动作是伸手去拿一个物体，第二个动作是将其放入一个小容器或大容器中。我们的结果表明，尽管在精细运动技能方面存在预期的困难，但即使在先天性小脑缺失的患者中，二阶运动规划（即根据第二个动作的性质调节第一个动作的能力）仍得以保留。这些结果引发了关于小脑在运动规划能力中作用的新的有趣猜测。尽管在根据单病例研究结果得出结论时必须谨慎，但这一证据提出了关于支持运动规划层次不同阶段的神经回路的迷人假设，以及二阶运动规划在运动认知中的功能作用及其在自闭症中可能出现的功能障碍。传统上，小脑被认为对运动规划至关重要。通过研究一名患有极其罕见的小脑发育不全的患者和一组神经典型对照组，我们发现即使在这名先天性小脑缺失的患者中，运动规划层次的高级阶段也可以保留。我们的结果提供了有趣的见解，有助于揭示支持不同运动规划水平的神经回路。此外，这些结果因其在自闭症中的潜在临床意义而引人关注。
