Parsons L M, Bower J M, Gao J H, Xiong J, Li J, Fox P T
Research Imaging Center, Medical School, University of Texas Health Science Center at San Antonio 78284, USA.
Learn Mem. 1997 May-Jun;4(1):49-62. doi: 10.1101/lm.4.1.49.
This study examined a new hypothesis proposing that the lateral cerebellum is not activated by motor control per se, as widely assumed, but is engaged during the acquisition and discrimination of tactile sensory information. This proposal derives from neurobiological studies of these regions of the rat cerebellum. Magnetic resonance imaging of the lateral cerebellar output nucleus (dentate) of humans during passive and active sensory tasks confirmed four a priori implications of this hypothesis. Dentate nuclei responded to cutaneous stimuli, even when there were no accompanying overt finger movements. Finger movements not associated with tactile sensory discrimination produced no dentate activation. Sensory discrimination with the fingers induced an increase in dentate activation, with or without finger movements. Finally, dentate activity was greatest when there was the most opportunity to modulate the acquisition of the sensory tactile data: when the discrimination involved the active repositioning of tactile sensory surface of the fingers. Furthermore, activity in cerebellar cortex was strongly correlated with observed dentate activity. This distinct four-way pattern of effects strongly challenges other cerebellar theories. However, contrary to appearances, neither our hypothesis nor findings conflict with behavioral effects of cerebellar damage, neurophysiological data on animals performing motor tasks, or cerebellar contribution to nonmotor, perceptual, and cognitive tasks.
本研究检验了一种新假说，该假说提出外侧小脑并非如广泛假设的那样，由运动控制本身激活，而是在触觉感觉信息的获取和辨别过程中发挥作用。这一观点源自对大鼠小脑这些区域的神经生物学研究。在被动和主动感觉任务期间对人类外侧小脑输出核（齿状核）进行的磁共振成像证实了该假说的四个先验推论。齿状核会对皮肤刺激产生反应，即便没有伴随明显的手指运动。与触觉感觉辨别无关的手指运动不会引起齿状核激活。用手指进行感觉辨别会导致齿状核激活增加，无论有无手指运动。最后，当有最大机会调节感觉触觉数据的获取时，即当辨别涉及手指触觉感觉表面的主动重新定位时，齿状核的活动最为强烈。此外，小脑皮质的活动与观察到的齿状核活动密切相关。这种独特的四重效应模式强烈挑战了其他小脑理论。然而，与表面现象相反，我们的假说和研究结果既不与小脑损伤的行为效应、动物执行运动任务的神经生理学数据，也不与小脑对非运动、感知和认知任务的贡献相冲突。
