ABSTRACT:Several functional neuroimaging studies have been performed exploring the sensorimotor function in children with neurologic disorders. However, little is known about normal activation patterns of the sensorimotor system at a young age. We explored brain representation of active and passive hand movements in schoolage children and young adults. Nine healthy children (7-15 y) and six adults were studied. Functional magnetic resonance imaging (fMRI) data were acquired on a 1.5-T scanner in block designs. Active movement consisted of repetitive opening and closing of the hand; passive movement consisted of the same movement performed by the examiner. Both hands were assessed separately. The pattern of brain activation (contralateral primary sensorimotor cortex (SMC), ipsilateral cerebellum, supplementary motor area (SMA), and lateral premotor cortex (PMC) was generally more widespread in the adult group, suggesting a developmental course in the organization of both motor and sensory cortex. Surprisingly, no difference was generally detected when contrasting active versus passive tasks. Our results suggest that active and passive hand movements can be used for the exploration of the sensorimotor system in children. Passive and active tasks confirmed to be tightly coupled, thus supporting the idea of the former as a helpful performance-independent paradigm in the study of brain reorganization and presurgical assessment. widely investigated in normal and pathologic subjects by means of functional neuroimaging techniques (1). For this purpose, active and passive hand or finger movements in sequences of various complexity are commonly used as activation tasks for the exploration of different components of the system. Studies in adults have consistently shown significant activation of contralateral rolandic regions (i.e. the pre-and postcentral gyrus) both during active and passive movements, with different types of repetitive tasks. Other regions are also usually activated such as the SMA, the PMC, and the ipsilateral cerebellum (1-9). Surprisingly, when comparing active and passive tasks, very little differential activation has been generally shown, particularly at the level of the rolandic region, which could be expected to be differentially involved in the two conditions (9).Little is known about brain representation of active and passive movements in children. Some knowledge about active motor tasks derives from studies with small control groups (3,10), which showed similar patterns of activation to those reported in adult studies (5,9,11,12). Nevertheless, the only study that systematically compared active movements in children and adults (repetitive hand squeezing of a ball) reported a significantly wider activation in the latter, particularly at the level of the primary SMC, the SMA, and the cerebellum (13). No studies on passive movement in normal children have been published so far, and no data are therefore available comparing children and adult passive movements or active and passive tasks in children...