In other words, task-related brain activation was greater in left primary motor cortex (leg) in subjects with SCI with greater cord damage.
Clinical impairment is predicted by non-invasive imaging of spinal atrophy and cortical reorganization, in particular, cervical cord area, BOLD signal and grey matter volume in primary motor cortex leg area, and BOLD signal in primary sensory cortex face area.
However, as subjects with better upper limb function did not show an increased grey matter volume in the primary motor cortex leg area, an alternative interpretation could be that greater disability induces greater cortical reorganization but that this does not translate into functional gain.
Although we did not observe any time-locked leg muscle movements during the handgrip task, this does not exclude the possibility of subtle co-contractions (for example, of the extensor hallucis), which could contribute to the activation in the primary motor cortex leg area.
Functional magnetic resonance imaging revealed increased activation in the left primary motor cortex leg area during handgrip and the left primary sensory cortex face area during median nerve stimulation in subjects with spinal cord injury compared with controls, but no increased activation following tibial nerve stimulation.
For the VBM and VBCT analysis, a 10-mm sphere was centred on x = ���6, y = −28, z = 60 for primary motor cortex leg area (from Ciccarelli et al., 2005), on x = −42, y = −18, z = 58 for primary motor cortex hand area (from Talelli et al., 2008), and on x = −4, y = −46, z = 62 (from Ferretti et al., 2003) for primary sensory cortex leg area, in the Montreal Neurological Institute coordinate system.
To reproduce the natural activation pattern of these muscle synergies during locomotion, we interfaced the leg motor cortex activity with neuromodulation therapies in non-human primates.
To investigate the effect of dual-mode noninvasive brain stimulation (NIBS) with high-frequency repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex of the lower leg and anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex compared with rTMS alone in patients with Parkinson disease (PD) with freezing of gait (FOG).
In addition, (hypothesis-led) searches for significant effects were restricted to a priori regions of interest corresponding to primary motor cortex and primary sensory leg and hand areas, and white matter regions along the corticospinal tract, to maximize sensitivity at a threshold of P < 0.05 (corrected for multiple comparison within region of interest).
For example, the excitatory and inhibitory effects of tDCS on leg motor cortex have been described, and although excitation could be provoked with anodal stimulation, even at 2 mA for 10 min they were unable to produce inhibition with cathodal stimulation (20).
In the central area, located over the sensory-motor cortex of legs, strong ERD was noticed in the alpha and beta bands in both condition 2 and 3 and was in the same frequency range for MI and for FES.
