Department of Psychology, University of Helsinki, Finland.
J Cogn Neurosci. 2010 Nov;22(11):2663-76. doi: 10.1162/jocn.2009.21382.
We applied fMRI and diffusion-weighted MRI to study the segregation of cognitive and motor functions in the human cerebro-cerebellar system. Our fMRI results show that a load increase in a nonverbal auditory working memory task is associated with enhanced brain activity in the parietal, dorsal premotor, and lateral prefrontal cortices and in lobules VII-VIII of the posterior cerebellum, whereas a sensory-motor control task activated the motor/somatosensory, medial prefrontal, and posterior cingulate cortices and lobules V/VI of the anterior cerebellum. The load-dependent activity in the crus I/II had a specific relationship with cognitive performance: This activity correlated negatively with load-dependent increase in RTs. This correlation between brain activity and RTs was not observed in the sensory-motor task in the activated cerebellar regions. Furthermore, probabilistic tractography analysis of the diffusion-weighted MRI data suggests that the tracts between the cerebral and the cerebellar areas exhibiting cognitive load-dependent and sensory-motor activity are mainly projected via separated pontine (feed-forward tracts) and thalamic (feedback tracts) nuclei. The tractography results also indicate that the crus I/II in the posterior cerebellum is linked with the lateral prefrontal areas activated by cognitive load increase, whereas the anterior cerebellar lobe is not. The current results support the view that cognitive and motor functions are segregated in the cerebellum. On the basis of these results and theories of the function of the cerebellum, we suggest that the posterior cerebellar activity during a demanding cognitive task is involved with optimization of the response speed.
我们应用 fMRI 和弥散加权 MRI 来研究人类大脑小脑系统中认知和运动功能的分离。我们的 fMRI 结果表明，在非言语听觉工作记忆任务中，随着负荷的增加，顶叶、背侧运动前皮质和外侧前额叶皮质以及小脑后部 VII-VIII 叶的脑活动增强，而感觉运动控制任务激活了运动/体感、内侧前额叶和后扣带回皮质以及小脑前叶的 V/VI 叶。小脑 crus I/II 中的负荷依赖性活动与认知表现具有特定关系：这种活动与反应时间的负荷依赖性增加呈负相关。在小脑激活区域的感觉运动任务中，没有观察到这种脑活动与反应时间之间的相关性。此外，弥散加权 MRI 数据的概率追踪分析表明，在表现出认知负荷依赖性和感觉运动活动的大脑和小脑区域之间的束，主要通过分开的脑桥（前馈束）和丘脑（反馈束）核投射。追踪结果还表明，小脑后部 crus I/II 与认知负荷增加激活的外侧前额叶区域相连，而小脑前叶没有。目前的结果支持这样一种观点，即认知和运动功能在小脑内是分离的。基于这些结果和小脑功能的理论，我们认为在高要求的认知任务中，小脑后部的活动与响应速度的优化有关。
