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Functional organization of hand movement in children and adults
ABSTRACTS
Functional Organization of Hand Movement in Children and Adults Ralph-Axel Miiller, Otto Muzik, Thomas J. Mangner & Harry T. Chugani Children's Hospital of Michigan, Wayne State University, Detroit, MI, USA
Introduction Numerous brain mapping studies have shown that finger movement in adults is mainly associated with activations in the contralateral rolandic and premotor cortex, as well as the supplementary motor area (e.g., 1, 2). The present study examines possible developmental changes in the functional network for hand motor control from childhood to maturity and explores which regions might be additionally involved in motor control during childhood. Since PET data for healthy children are unavailable, movement of the non-affected hand was studied in patients with unilateral lesions. Our hypothesis was that due to prolonged practice and automatization motor control in adults would (a) be less distributed, and (b) rely on cerebellar structures to a greater extent than in children.
Subjects
and methods
23 patients with unilateral brain lesion were studied by means of [150]-water PET. Patients were assigned to 2 age groups. The child group consisted of 11 patients (6 left-, 5 right-lesioned), aged 6-16ys. (mean: 12.3ys.). The adult group was formed by 12 patients (7 left-, 5 right-lesioned), aged 18-74ys. (mean: 39ys.). Regional cerebral blood flow (rCBF) was studied for rest and opposing finger-thumb movement of the hand ipsilateral to the lesion. Both conditions were scanned twice with a Siemens Exact HR scanner (47 planes). Images were coregistered, normalized, averaged, and subtracted (movement minus rest) intraindividually by means of the Minoshima et al. package (3), incorporating a pooled-variance t(Z)-statistic (4). Peaks of rCBF increase were allocated to 28 cortical and 11 subcortical regions of interest (ROIs). Activations in the temporal lobes were not examined. Only peaks of z_>3 were considered significant. The highest z-scores per region, patient, and subtraction were group-averaged to yield mean regional activations. In addition, the number of ROIs with significant peaks was used as a measure of activational distributivity, As an exploratory measure of group trends, comparisons were performed by means of an unpaired, two-tailed t-Test (without Bonferroni correction).
Results The region with highest mean activation (in both groups likewise) was the contralateral rolandic cortex, followed by the ipsilateral cerebellum, the contralateral cerebellum, and the vermis (see TABLE). Unexpectedly, distributivity was higher in the adult than in the child group. The Mean activation mean number of non-rolandic ROIs activated was 8.8 ROI side Children Adults Trend in the adult and 7.1 in the child group. However, a Prefrontal C 2.1 0.3 Ch > Ad trend for greater mean activations in the child group Orbitofrontal C 1.3 0.0 Ch > Ad ~l was seen in the prefrontal and orbitofrontal ROIs Ant. cingulate I 0.3 1.7 Ad>Ch~ contralateral to the movement. The adult group Rolandic C 4.5 4.7 Insula C 0.0 1.6 Ad > Ch * showed higher mean activations in the ipsilateral Inf. parietal I 0.0 0.8 (Ad > Ch) anterior cingulate and the contralateral insular ROI. C 1.3 2.1 (Ad > Ch) Mild trends of stronger rCBF increases for the adult Vermis 2.1 2.6 group were also seen in the ipsilateral supplementary Cerebellum I 4.1 3.8 motor area and thalamus, the bilateral inferior parietal C 2.5 3.3 (Ad > Ch) lobe, and the contralateral cerebellum. Overall, the Mean activations for selected ROIs (C = contralateral, I = average number of ipsilateral supratentorial areas ipsilateral; Ch = Children, Ad = Adults; *: p<.01; ~: p<.05). activated was higher for the adults (2.4 vs. 1.5).
Conclusion As expected from previous studies with normal adults (1, 2), finger movement robustly activated the contralateral rolandic cortex. However, premotor and supplementary motor activations were less pronounced in our subjects, whereas activations in the bilateral cerebellum and the vermis were unexpectedly strong. The hypothesis of more distributed activations for finger movement in the child group was not confirmed. On the contrary, rCBF increases were on average more distributed in the adults. However, the contralateral prefrontal and orbitofrontal cortex was more strongly activated in the child group, indicating a more distributed motor representation within the frontal lobe. As expected, greater cerebellar involvement was found in the adult group, but this trend was weak and valid only for the contralateral cerebellum. The latter finding corresponds to the greater involvement of supratentorial structures ipsilateral to the movement in the adult group. Further studies will be necessary to evaluate to what extent the results from this pseudonormal population can be applied to normal developmental patterns of motor organization.
References 1. 2. 3. 4.
Colebatch, JG, Deiber, M-P et al. Journal of Neurophysiology. 1991, 65: 1392-1401. Kawashima, R, Yamada, K et al. Brain Research. 1993, 623: 33-40. Minoshima, S, et al. In: Quantification of Brain Function. K. Uemura et al., eds. Elsevier, 1993: pp. 409-15. Worsley, KJ, Evans, AC et al. Journal of Cerebral Blood Flow and Metabolism. 1992, 12: 900-18.
$402
Functional Organization of Hand Movement in Children and Adults Ralph-Axel Miiller, Otto Muzik, Thomas J. Mangner & Harry T. Chugani Children's Hospital of Michigan, Wayne State University, Detroit, MI, USA
Introduction Numerous brain mapping studies have shown that finger movement in adults is mainly associated with activations in the contralateral rolandic and premotor cortex, as well as the supplementary motor area (e.g., 1, 2). The present study examines possible developmental changes in the functional network for hand motor control from childhood to maturity and explores which regions might be additionally involved in motor control during childhood. Since PET data for healthy children are unavailable, movement of the non-affected hand was studied in patients with unilateral lesions. Our hypothesis was that due to prolonged practice and automatization motor control in adults would (a) be less distributed, and (b) rely on cerebellar structures to a greater extent than in children.
Subjects
and methods
23 patients with unilateral brain lesion were studied by means of [150]-water PET. Patients were assigned to 2 age groups. The child group consisted of 11 patients (6 left-, 5 right-lesioned), aged 6-16ys. (mean: 12.3ys.). The adult group was formed by 12 patients (7 left-, 5 right-lesioned), aged 18-74ys. (mean: 39ys.). Regional cerebral blood flow (rCBF) was studied for rest and opposing finger-thumb movement of the hand ipsilateral to the lesion. Both conditions were scanned twice with a Siemens Exact HR scanner (47 planes). Images were coregistered, normalized, averaged, and subtracted (movement minus rest) intraindividually by means of the Minoshima et al. package (3), incorporating a pooled-variance t(Z)-statistic (4). Peaks of rCBF increase were allocated to 28 cortical and 11 subcortical regions of interest (ROIs). Activations in the temporal lobes were not examined. Only peaks of z_>3 were considered significant. The highest z-scores per region, patient, and subtraction were group-averaged to yield mean regional activations. In addition, the number of ROIs with significant peaks was used as a measure of activational distributivity, As an exploratory measure of group trends, comparisons were performed by means of an unpaired, two-tailed t-Test (without Bonferroni correction).
Results The region with highest mean activation (in both groups likewise) was the contralateral rolandic cortex, followed by the ipsilateral cerebellum, the contralateral cerebellum, and the vermis (see TABLE). Unexpectedly, distributivity was higher in the adult than in the child group. The Mean activation mean number of non-rolandic ROIs activated was 8.8 ROI side Children Adults Trend in the adult and 7.1 in the child group. However, a Prefrontal C 2.1 0.3 Ch > Ad trend for greater mean activations in the child group Orbitofrontal C 1.3 0.0 Ch > Ad ~l was seen in the prefrontal and orbitofrontal ROIs Ant. cingulate I 0.3 1.7 Ad>Ch~ contralateral to the movement. The adult group Rolandic C 4.5 4.7 Insula C 0.0 1.6 Ad > Ch * showed higher mean activations in the ipsilateral Inf. parietal I 0.0 0.8 (Ad > Ch) anterior cingulate and the contralateral insular ROI. C 1.3 2.1 (Ad > Ch) Mild trends of stronger rCBF increases for the adult Vermis 2.1 2.6 group were also seen in the ipsilateral supplementary Cerebellum I 4.1 3.8 motor area and thalamus, the bilateral inferior parietal C 2.5 3.3 (Ad > Ch) lobe, and the contralateral cerebellum. Overall, the Mean activations for selected ROIs (C = contralateral, I = average number of ipsilateral supratentorial areas ipsilateral; Ch = Children, Ad = Adults; *: p<.01; ~: p<.05). activated was higher for the adults (2.4 vs. 1.5).
Conclusion As expected from previous studies with normal adults (1, 2), finger movement robustly activated the contralateral rolandic cortex. However, premotor and supplementary motor activations were less pronounced in our subjects, whereas activations in the bilateral cerebellum and the vermis were unexpectedly strong. The hypothesis of more distributed activations for finger movement in the child group was not confirmed. On the contrary, rCBF increases were on average more distributed in the adults. However, the contralateral prefrontal and orbitofrontal cortex was more strongly activated in the child group, indicating a more distributed motor representation within the frontal lobe. As expected, greater cerebellar involvement was found in the adult group, but this trend was weak and valid only for the contralateral cerebellum. The latter finding corresponds to the greater involvement of supratentorial structures ipsilateral to the movement in the adult group. Further studies will be necessary to evaluate to what extent the results from this pseudonormal population can be applied to normal developmental patterns of motor organization.
References 1. 2. 3. 4.
Colebatch, JG, Deiber, M-P et al. Journal of Neurophysiology. 1991, 65: 1392-1401. Kawashima, R, Yamada, K et al. Brain Research. 1993, 623: 33-40. Minoshima, S, et al. In: Quantification of Brain Function. K. Uemura et al., eds. Elsevier, 1993: pp. 409-15. Worsley, KJ, Evans, AC et al. Journal of Cerebral Blood Flow and Metabolism. 1992, 12: 900-18.
$402