COMPARING MOTION-RELATED AND IMAGERY-RELATED ACTIVATION IN THE HUMAN CEREBELLUM - A FUNCTIONAL MRI STUDY

Cerebellar activation during execution and imagination of a finger mov ement was compared. Functional magnetic resonance imaging was used to detect cerebellar activation during execution and imagination of an un trained self-paced finger-to-thumb movement (left and right hand separ ately). The few: fingers were opposed to the thumb in changing sequenc es freely chosen by the subjects. The activation maps of 10 right-hand ed healthy subjects were averaged after transformation into a common c oordinate space. Averaged activation maps revealed strong motion-relat ed bilateral activation in the anterior lobe of the cerebellum and in the paravermal regions of the posterior lobe. Ipsilateral activity pre dominated significantly. Compared to motion, imagination of the same t ask produced lower signal changes, and foci were more variable in posi tion and strength. The averaged activation maps showed activity in the same regions as in motion. Activation in the posterior cerebellar lob e was more prominent extending into the lateral hemispheres. Ipsilater al dominance was significant for right-hand imagery The left-hand task only showed marginally stronger ipsilateral activation. The activatio n pattern observed during execution of the finger-to-thumb movement is in agreement with theories of functional cerebellar topography. For i magery, activation at a comparable location may reflect common functio nality, e.g., motor preparation and/or timing. Additional activation i n the lateral hemispheres may be related to an imagery-specific functi on. (C) 1998 Wiley-Liss, Inc.