BACKGROUND: Accumulating evidence suggests anatomical and functional differences in connectivity between the anterior and posterior parts of the inferior-parietal lobule (IPL) and the frontal motor areas. OBJECTIVE/HYPOTHESIS: This study investigates whether different intra-hemispheric parietal-motor interactions can be observed along the anterior-posterior axis of the IPL in the resting human brain. METHODS: We use a twin coil transcranial magnetic stimulation technique to test intra-hemispheric interactions between three points adjacent to the intra-parietal sulcus (anterior, central, posterior) and the ipsilateral primary motor cortex (M1) at rest in both hemispheres. RESULTS: We found that stimulation of the anterior IPL resulted in an inhibition of the ipsilateral M1 in both hemispheres. Stimulation of the central and posterior IPL resulted in a facilitatory effect on ipsilateral M1 in the left but not for the right hemisphere. Additionally we show that there is considerable inter-subject variability concerning the optimal parietal facilitatory and inhibitory position. CONCLUSIONS: The IPL has distinct inhibitory and facilitatory connections to the ipsilateral M1. Whereas inhibitory connections are observed in both hemispheres, facilitatory connections are asymmetric. These parietal-motor networks may represent the basis for the functional differences between these regions in reaching and grasping tasks and mirror the functional asymmetry observed in the motor system. From a practical point of view, we note that the inter-subject variability means that future TMS studies of the parietal area might consider a hot-spot localization similar to the procedures commonly used for M1. Published by Elsevier Inc.
BACKGROUND: Accumulating evidence suggests anatomical and functional differences in connectivity between the anterior and posterior parts of the inferior-parietal lobule (IPL) and the frontal motor areas. OBJECTIVE/HYPOTHESIS: This study investigates whether different intra-hemispheric parietal-motor interactions can be observed along the anterior-posterior axis of the IPL in the resting human brain. METHODS: We use a twin coil transcranial magnetic stimulation technique to test intra-hemispheric interactions between three points adjacent to the intra-parietal sulcus (anterior, central, posterior) and the ipsilateral primary motor cortex (M1) at rest in both hemispheres. RESULTS: We found that stimulation of the anterior IPL resulted in an inhibition of the ipsilateral M1 in both hemispheres. Stimulation of the central and posterior IPL resulted in a facilitatory effect on ipsilateral M1 in the left but not for the right hemisphere. Additionally we show that there is considerable inter-subject variability concerning the optimal parietal facilitatory and inhibitory position. CONCLUSIONS: The IPL has distinct inhibitory and facilitatory connections to the ipsilateral M1. Whereas inhibitory connections are observed in both hemispheres, facilitatory connections are asymmetric. These parietal-motor networks may represent the basis for the functional differences between these regions in reaching and grasping tasks and mirror the functional asymmetry observed in the motor system. From a practical point of view, we note that the inter-subject variability means that future TMS studies of the parietal area might consider a hot-spot localization similar to the procedures commonly used for M1. Published by Elsevier Inc.
Authors: Nikos Makris; David N Kennedy; Sean McInerney; A Gregory Sorensen; Ruopeng Wang; Verne S Caviness; Deepak N Pandya Journal: Cereb Cortex Date: 2004-12-08 Impact factor: 5.357
Authors: Chi-Chao Chao; Anke Ninija Karabanov; Rainer Paine; Ana Carolina de Campos; Sahana N Kukke; Tianxia Wu; Han Wang; Mark Hallett Journal: Cereb Cortex Date: 2013-08-22 Impact factor: 5.357
Authors: Shabbir Hussain I Merchant; Eleni Frangos; Jacob Parker; Megan Bradson; Tianxia Wu; Felipe Vial-Undurraga; Giorgio Leodori; M C Bushnell; Silvina G Horovitz; Mark Hallett; Traian Popa Journal: Brain Date: 2020-06-01 Impact factor: 13.501
Authors: Mark Hallett; Riccardo Di Iorio; Paolo Maria Rossini; Jung E Park; Robert Chen; Pablo Celnik; Antonio P Strafella; Hideyuki Matsumoto; Yoshikazu Ugawa Journal: Clin Neurophysiol Date: 2017-09-05 Impact factor: 3.708