Objectives: To assess the contralesional connectivity between the posterior parietal cortex (PPC) and the motor cortex (M1) in stroke patients, and to probe putative relationships with spatial neglect and motor impairment.
Methods: In 12 right-side stroke patients and 12 age-matched healthy controls, we used paired-pulse transcranial magnetic stimulation to assess the contralesional connectivity between three left-side PPC sites (the anterior intraparietal sulcus (aIPS), the posterior intraparietal sulcus and the superior parieto-occipital cortex (SPOC)) and M1. The interstimulus interval (ISI) was set to 4 or 6ms.
Results: Although there were no differences between the stroke patient group and the controls, a subgroup analysis showed that stimulation over the SPOC with an ISI of 6ms facilitated motor-evoked potential responses in patients with neglect (and especially those with severe peripersonal neglect), relative to non-neglect patients. With an ISI of 4ms, the aIPS exerted an inhibitory influence on M1 in all subjects. The severity of motor impairment was not associated with PPC-M1 connectivity.
Conclusions: aIPS-M1 connectivity seems to be unaffected in stroke patients, whereas connectivity from the most posterior parts of the parietal cortex depends on the patient's neglect status.
Significance: These results provide insight into post-stroke changes in contralesional PPC-M1 connectivity.
Keywords: Connectivity; Motor impairment; Parietal cortex; Spatial neglect; Stroke; Transcranial magnetic stimulation.
Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.