Functional topography of the cerebellum for motor and cognitive tasks: an fMRI study

Abstract

Anatomical, clinical and imaging findings suggest that the cerebellum is engaged in cognitive and affective functions as well as motor control. Evidence from converging modalities also indicates that there is a functional topography in the human cerebellum for overt control of movement vs. higher functions, such that the cerebellum can be divided into zones depending on connectivity with sensorimotor vs. multimodal association cortices. Using functional MRI, we show that regions active during overt movement differ from those involved in higher-level language, spatial processing and working memory tasks. Nine healthy participants each completed five tasks in order to determine the relative activation patterns for the different paradigms. Right-handed finger-tapping activated right cerebellar lobules IV-V and VIII, consistent with descriptions of the cerebellar homunculi. Verb generation engaged right cerebellar lobules VI-Crus I and a second cluster in lobules VIIB-VIIIA. Mental rotation activation peaks were localized to medial left cerebellar lobule VII (Crus II). A 2-back working memory task activated bilateral regions of lobules VI-VII. Viewing arousing vs. neutral images did not reliably activate the cerebellum or cerebral limbic areas in this study. The cerebellar functional topography identified in this study reflects the involvement of different cerebro-cerebellar circuits depending on the demands of the task being performed: overt movement activated sensorimotor cortices along with contralateral cerebellar lobules IV-V and VIII, whereas more cognitively demanding tasks engaged prefrontal and parietal cortices along with cerebellar lobules VI and VII. These findings provide further support for a cerebellar role in both motor and cognitive tasks, and better establish the existence of functional subregions in the cerebellum. Future studies are needed to determine the exact contribution of the cerebellum - and different cerebro-cerebellar circuits - to task performance.

Figure 1

fMRI results. Cerebellar activation patterns for finger tapping (red), verb generation (cyan), mental rotation (green) and the n-back task (violet) are shown on sagittal (top row), axial (middle row) and coronal (bottom row) slices through the cerebellum. Regions where verb generation and n-back activation overlap are outlined in black. A 3-D rendering of the activation patterns is shown on the left, with a cutout at x = -5, y = -56, z = -45 (MNI coordinates). Activation maps are thresholded at a voxel-level threshold of P < 0.0001 (uncorrected) with a cluster-level correction of P < 0.05 (corrected for false-discovery rate [FDR]). Left is shown on the left.

Figure 2

fMRI results. Whole-brain activation patterns for (from top to bottom) finger tapping (red); n-back (violet); verb generation (cyan); mental rotation (green); and IAPS (yellow) tasks. Activation maps are thresholded at a voxel-level threshold of P < 0.0001 (uncorrected) with a cluster-level correction of P < 0.05 (corrected for false-discovery rate [FDR]). Left is shown on the left. IFG, inferior frontal gyrus; IOG, inferior occipital gyrus; IPL, inferior parietal lobule; MFG, middle frontal gyrus; MedFG, medial frontal gyrus; MOG, middle occipital gyrus; MT, middle temporal; SMA, supplementary motor area.

Figure 3

Sensorimotor vs. cognitive activation patterns. Regions where finger tapping > cognitive tasks (verb generation, n-back and mental rotation) are shown in red; regions where cognitive > finger tapping are shown in blue. A 3-D rendering of the activation patterns is shown on the left, with a cutout at x = 9, y = -19, z = 18 (MNI coordinates). Activation maps are thresholded at a voxel-level threshold of P < 0.0001 (uncorrected) with a cluster-level FDR-corrected P < 0.05. Left is shown on the left. Labeling is based on entire activation cluster, not all of which may appear in a given slice (see Table 6). IPL, inferior parietal lobule; MFG, middle frontal gyrus; SPL, superior parietal lobule.

Figure 4

Converging evidence of cerebellar topography from a meta-analysis of published imaging data (Stoodley and Schmahmann, 2009), a single-case study (Stoodley et al., 2010), and the present study. Consistently active clusters during motor (red; right-handed finger movement), language (blue), spatial (green) and working memory (purple) paradigms are shown on coronal cerebellar slices. Left is shown on the left.