RESEARCH ARTICLE O. Ciccarelli Æ A. T. Toosy Æ J. F. Marsden C. M. Wheeler-Kingshott Æ C. Sahyoun P. M. Matthews Æ D. H. Miller Æ A. J. Thompson Identifying brain regions for integrative sensorimotor processing with ankle movements Received: 25 October 2004 / Accepted: 22 February 2005 / Published online: 21 July 2005 Ó Springer-Verlag 2005 Abstract The objective of this study was to define cor- tical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor inte- gration. Sixteen healthy subjects, all right-foot domi- nant, performed a dorsi-plantar flexion task of the foot using a custom-made wooden manipulandum, which enabled measurements of the movement amplitude. All subjects underwent a training session, which included surface electromyography, and were able to relax com- pletely during passive movements. Patterns of activation during active and passive movements and differences between functional MRI (fMRI) responses for the two types of movement were assessed. Regions of common activation during the active and passive movements were identified by conjunction analysis. We found that pas- sive movements activated cortical regions that were usually similar in location to those activated by active movements, although the extent of the activations was more limited with passive movements. Active move- ments of both feet generated greater activation than passive movements in some regions (such as the ipsi- lateral primary motor cortex) identified in previous studies as being important for motor planning. Common activations during active and passive movements were found not only in the contralateral primary motor and sensory cortices, but also in the premotor cortical re- gions (such as the bilateral rolandic operculum and contralateral supplementary motor area), and in the subcortical regions (such as the ipsilateral cerebellum and contralateral putamen), suggesting that these re- gions participate in sensorimotor integration for ankle movements. In future, similar fMRI studies using pas- sive movements have potential to elucidate abnormali- ties of sensorimotor integration in central nervous system diseases that affect motor function. Key words Functional MRI Æ Motor system Æ Active movement Æ Passive movement Æ Sensorimotor integration Introduction Volitional movement is associated with activation of a widespread cortical and subcortical network (Kandel et al. 2000). In an attempt to define the contribution of afferent feedback to this activation, comparisons have been made between active and passive movements. Positron emission tomography (PET) (Mima et al. 1999; Weiller et al. 1996; Yetkin et al. 1995) and functional MRI (fMRI) studies (Reddy et al. 2001; Yetkin et al. 1995) have consistently demonstrated that both active and passive hand movements activate the contralateral primary somatosensory and motor areas. Studies have also shown that premotor areas, supplementary motor cortex, and subcortical structures are similarly activated during both types of movement (Jueptner et al. 1997; Reddy et al. 2001; Thickbroom et al. 2003; Weiller et al. 1996). This supports the hypothesis that the basal gan- glia and the cerebellum play a role in sensorimotor processing. Other authors, however, have not found O. Ciccarelli (&) Æ A. T. Toosy Æ A. J. Thompson Department of Headache, Brain Injury and Rehabilitation, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK E-mail: o.ciccarelli@ion.ucl.ac.uk Tel.: +44 207 8373611 ext 4152 Fax: + 44 207 8136505 O. Ciccarelli Æ C. Sahyoun Æ P. M. Matthews Centre for Functional Magnetic Resonance Imaging of the Brain, John Radcliffe Hospital, Headington, Oxford, OX3 DU, UK J. F. Marsden MRC Human Movement Group, Sobell Department for Motor Neurophysiology and Movement Disorders, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK C. M. Wheeler-Kingshott Æ D. H. Miller Department of Neuroinflammation, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK Exp Brain Res (2005) 166: 31–42 DOI 10.1007/s00221-005-2335-5