Influence of Corticospinal Tracts from Higher Order Motor Cortices on Recruitment Curve Properties in Stroke

Abstract

Background: Recruitment curves (RCs) acquired using transcranial magnetic stimulation are commonly used in stroke to study physiologic functioning of corticospinal tracts (CST) from M1. However, it is unclear whether CSTs from higher motor cortices contribute as well.Objective: To explore whether integrity of CST from higher motor areas, besides M1, relates to CST functioning captured using RCs.Methods: RCs were acquired for a paretic hand muscle in patients with chronic stroke. Metrics describing gain and overall output of CST were collected. CST integrity was defined by diffusion tensor imaging. For CST emerging from M1 and higher motor areas, integrity (fractional anisotropy) was evaluated in the region of the posterior limb of the internal capsule, the length of CST and in the region of the stroke lesion.Results: We found that output and gain of RC was related to integrity along the length of CST emerging from higher motor cortices but not the M1.Conclusions: Our results suggest that RC parameters in chronic stroke infer function primarily of CST descending from the higher motor areas but not M1. RCs may thus serve as a simple, in-expensive means to assess re-mapping of alternate areas that is generally studied with resource-intensive neuroimaging in stroke.

Inhibition versus facilitation of contralesional motor cortices in stroke: Deriving a model to tailor brain stimulation

“…FMRI maxima can help localize reorganized territory within M1 that is activated in association with movement of the paretic hand (Lotze et al, 2003, Diekhoff et al, 2011). Stereotactic mapping grids (3 × 5) were centered at the site of fMRI activation maxima (Potter-Baker et al, 2016). All sites within the mapping grid were targeted with TMS using stereotactic navigation, while motor-evoked potentials (MEPs) were recorded (PowerLab 4/25T, AD Instruments, Colorado Springs, CO) from the paretic extensor digitorum communis (EDC) muscle using surface electromyography (EMG) electrodes (silver-silver chloride, 45 mm diameter).…”

Ipsilesional High Frequency Repetitive Transcranial Magnetic Stimulation Add-On Therapy Improved Diffusion Parameters of Stroke Patients with Motor Dysfunction: A Preliminary DTI Study

“…These findings would reflect a boosting effect of rTMS on motor function recovery after stroke. Recent studies have shown that PLIC is mainly comprised of CST which control voluntary movement and is commonly used as the regions to the analysis of the integrity of CST [33, 34]. Compared to other brain regions, PLIC would have a closer relationship with motor function.…”

“…There is evidence that PLIC and CR were mainly comprised of CST which project from the motor cortex to the PLIC [34, 36, 37] and to brain stem [33]. Previous diffusion microstructural studies have showed significantly decreased FA values in ipsilesional [5, 38, 39] and contralesional [24, 40] PLIC and CST after stroke.…”

Effects of regiolects on the perception of developmental foreign accent syndrome

“…Here we investigate whether the electrophysiological evaluation of the Motor Evoked Potentials (MEPs) stimulating the corticomotor pathway using Transcranial Magnetic Stimulation (TMS) could improve the prediction of post stroke aphasia recovery. MEPs seem to be a good predictor of motor recovery [11][12][13][14] . This approach could also be used to investigate prediction of aphasia recovery studying a modulation of the cortical excitability of motor areas.…”