Cognitive and Motor Loops of the Human Cerebro-cerebellar System

Abstract

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.

Does Contralesional Hand Function After Neonatal Stroke Only Depend on Lesion Characteristics?

“…11 The premotor cortex and the primary motor area show connections with the contralateral Crus I via the mediodorsal thalamus. 12 Hence, our results would further support the hypothesis of an important combined role for the mediodorsal thalamus and lobule VIIa Crus I in the control of skilled hand movement. 10,13 Finally, we show that the correlation with manual dexterity found in brain areas directly or functionally connected but anatomically remote from the infarct is mainly because of atrophy of these structures in impaired children (except for the cerebellum).…”

Musical training intensity yields opposite effects on grey matter density in cognitive versus sensorimotor networks

“…Distinct loops exist between cerebellum and cortex for, respectively, cognitive and motor function. Functional neuroimaging in combination with diffusion-weighted MRI (Salmi et al 2009) revealed that the posterior cerebellum (Crus I and II), which is connected to lateral prefrontal areas, was activated by cognitive load increase in a nonverbal auditory memory task; in contrast, the anterior cerebellum (lobules V/VI), known to be involved in sensorimotor function, was not. An analysis on resting state functional connectivity observed the same dissociation: a primary sensorimotor zone (lobules V, VI and VIII) could be distinguished from a supramodal zone (lobules VIIa, Crus I, and II).…”

Functional Topography of the Human Cerebellum Revealed by Functional Neuroimaging Studies

“…Visual and verbal nback tasks engage similar cerebellar regions, suggesting that the role of the cerebellum during the n-back task is independent of modality (Hautzel et al 2009), although differences have been shown for visual and auditory working memory using a Sternberg paradigm (Kirschen et al 2010). Cerebellar activation has also been shown to increase as a function of increasing memory load (e.g., Beneventi et al 2007;Salmi et al 2010). …”

“…For example, Salmi et al (2010) used diffusion-weighted MRI to show that separate cerebro-ponto-cerebellar and cerebello-thalamic-cerebral tracts exist for lobules V-VI ("sensorimotor" circuit; connects with primary motor cortex and dorsal premotor cortex) and Crus I/II ("cognitive" circuit; connects with lateral prefrontal regions). Diffusion tensor imaging comparing the prefrontal cerebrocerebellar circuits between humans and nonhuman primates has shown that in the cerebral peduncles of the monkey, the majority of the corticopontine fibers are from the motor system, whereas in humans more fibers arise from prefrontal regions (Ramnani et al 2006).…”