Parietomotor connectivity in the contralesional hemisphere after stroke: A paired-pulse TMS study.
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.



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.



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.



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.



These results provide insight into post-stroke changes in contralesional PPC-M1 connectivity.
Neurorehabilitation Unit, Lille University Medical Center, 59000 Lille, France; Univ. Lille, Inserm U1171-Degenerative and Vascular Cognitive Disorders, 59000 Lille, France. Electronic address: Etienne.allart@chru-lille.fr.
Etienne
E
Allart
Univ. Lille, Inserm U1171-Degenerative and Vascular Cognitive Disorders, 59000 Lille, France; Department of Clinical Neurophysiology, Lille University Medical Center, 59000 Lille, France.
Arnaud
A
Delval
ULCO, URePSSS Unité de Recherche Pluridisciplinaire Sport Santé Société (EA7369), 62228 Calais, France.
Alexandre
A
Caux-Dedeystere
Department of Biostatistics, EA2694--Santé publique: épidémiologie et qualité des soins, Lille University, 59000 Lille, France.
Julien
J
Labreuche
Univ. Lille, Inserm U1171-Degenerative and Vascular Cognitive Disorders, 59000 Lille, France; Clinical Imaging Core Facility, Lille University Medical Center, 59000 Lille, France.
Romain
R
Viard
Univ. Lille, Inserm U1171-Degenerative and Vascular Cognitive Disorders, 59000 Lille, France; Clinical Imaging Core Facility, Lille University Medical Center, 59000 Lille, France.
Renaud
R
Lopes
Department of Clinical Neurophysiology, Lille University Medical Center, 59000 Lille, France; ULCO, URePSSS Unité de Recherche Pluridisciplinaire Sport Santé Société (EA7369), 62228 Calais, France.
Hervé
H
Devanne
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D063132:Connectome; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D010296:Parietal Lobe / Q000503:physiopathology*; D020521:Stroke / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
Connectivity; Motor impairment; Parietal cortex; Spatial neglect; Stroke; Transcranial magnetic stimulation