Manzoni D
Dipartimento di Fisiologia Umana, Università di Pisa, Via S. Zeno 31, 56127 Pisa, Italy.
Cerebellum. 2007;6(1):24-37. doi: 10.1080/14734220601132135.
Cerebellar modules process afferent information and deliver outputs relevant for both reflex and voluntary movements. The response of cerebellar modules to a given input depends on the whole array of signals impinging on them. Studies on vestibular reflexes indicate that the response of the cerebellar circuits to the vestibular input is modified by the integration of multiple visual, vestibular and somatosensory afferent signals. In this way the cerebellum slowly adapts these reflexes when they are not adequate to the behavioural condition and allows their fast modifications when the relative position of the body segments and that of the body in space are changed. Studies on voluntary movements indicate that the cerebellum is responsible for motor learning that consists of the development of new input-output associations. Several theoretical, anatomical and clinical studies are consistent with the hypothesis that the cerebellum allows the delivery of motor commands which vary according to the condition of the motor apparatus. Finally, the cerebellum could change the relation between visual information and aimed reaching movements according to the position of the eyes in the orbit and of the neck over the body. We propose that, due to the large expansion of its cortex, an important function of the cerebellum could be that of expanding the range of sensorimotor associations according to all the factors characterizing the behavioural condition. Indeed, following cerebellar lesion, learning is often lost, the movement results impaired and requires an increased attention. In the light of the recently discovered connections of the cerebellum with the rostral regions of the frontal lobe, it can be suggested that the ability of cerebellar circuits to modify the rules of input-output coupling according to a general context is a fundamental property allowing the cerebellum to control not only motor but also cognitive functions.
小脑模块处理传入信息，并输出与反射和自主运动相关的信号。小脑模块对给定输入的反应取决于作用于它们的所有信号。对前庭反射的研究表明，小脑回路对前庭输入的反应会因多种视觉、前庭和体感传入信号的整合而改变。通过这种方式，当反射不足以适应行为条件时，小脑会缓慢调整这些反射；而当身体各部分以及身体在空间中的相对位置发生变化时，小脑又能使其快速改变。对自主运动的研究表明，小脑负责运动学习，即形成新的输入 - 输出关联。多项理论、解剖学和临床研究均支持这一假说：小脑能够根据运动器官的状态发出不同的运动指令。最后，小脑可根据眼睛在眼眶中的位置以及颈部相对于身体的位置，改变视觉信息与目标指向性运动之间的关系。我们认为，由于小脑皮质的大量扩展，其一项重要功能可能是根据行为条件的所有特征因素，扩大感觉运动关联的范围。事实上，小脑损伤后，学习能力常常丧失，运动结果受损，且需要更多注意力。鉴于最近发现的小脑与额叶前部区域的连接，有人提出，小脑回路根据总体情境修改输入 - 输出耦合规则的能力，是使其不仅能够控制运动功能，还能控制认知功能的一项基本特性。
