0000000001119988
AUTHOR
Diane Ruge
TMS activation of interhemispheric pathways between the posterior parietal cortex and the contralateral motor cortex
Using a twin coil transcranial magnetic stimulation (tc-TMS) approach we have previously demonstrated that facilitation may be detected in the primary motor cortex (M1) following stimulation over the ipsilateral caudal intraparietal sulcus (cIPS). Here we tested the interhemispheric interactions between the IPS and the contralateral motor cortex (M1). We found that conditioning the right cIPS facilitated contralateral M1 when the conditioning stimulus had an intensity of 90% resting motor threshold (RMT) but not at 70% or 110% RMT. Facilitation was maximal when the interstimulus interval (ISI) between cIPS and M1 was 6 or 12 ms. These facilitatory effects were mediated by interactions with …
Hyperexcitability of parietal-motor functional connections in the intact left-hemisphere of patients with neglect
Hemispatial neglect is common after unilateral brain damage, particularly to perisylvian structures in the right-hemisphere (RH). In this disabling syndrome, behaviour and awareness are biased away from the contralesional side of space towards the ipsilesional side. Theoretical accounts of this in terms of hemispheric rivalry have speculated that the intact left-hemisphere (LH) may become hyper-excitable after a RH lesion, due to release of inhibition from the damaged hemisphere. We tested this directly using a novel twin-coil transcranial magnetic stimulation (TMS) approach to measure excitability within the intact LH of neglect patients. This involved applying a conditioning TMS pulse ove…