Localizing the Primary Motor Cortex of the Hand by the 10-5 and 10-20 Systems for Neurostimulation: An MRI Study

Abstract

<jats:p> Background. The primary motor cortex of the hand (M1-Hand) is a target used in transcranial magnetic stimulation (TMS) and in transcranial direct current stimulation (tDCS) for the treatment and evaluation of motor neurological diseases. Magnetic resonance imaging–guided neuronavigation locates the M1-Hand with high precision, but at a high cost. Although less accurate, the C3/C4 points of the international 10-20 system (IS 10-20) are routinely used to locate the M1-Hand. The international 10-5 system (IS 10-5) was developed with additional points (C3h/C4h), which could make it more accurate, but has not yet been tested on the location of the M1-Hand. Objective. To analyze and compare the accuracy of C1/C2, C3h/C4h and C3/C4 points in locating the M1-Hand correspondence on the scalp. Methods. The authors comparatively analyzed the distances from points C1/C2, C3h/C4h, and C3/C4 to the correspondence of the M1-Hand on the scalp in 30 MRI head exams. Results. In most cases, the M1-Hand was located between C1-C3h and C2-C4h in the left and right hemispheres of the brain, respectively. The C3h (0.98 ± 0.49 cm) and C4h (0.98 ± 0.51 cm) points presented the shortest distances from the M1-Hand, with a significant difference when compared with C3/C4. The accuracy between C1/C2 and C3h/C4h was not statistically significant. Conclusion. The C3h/C4h and C1/C2 points were more accurate when compared with the C3 and C4 points in locating the M1-Hand correspondence on the scalp. </jats:p>

The rt-TEP tool: real-time visualization of TMS-Evoked Potential to maximize cortical activation and minimize artifacts

“…For this reason, when targeting the primary motor cortex (M1), TMS stimulation parameters (position, angle, intensity) are initially set based on coarse a priori anatomical information (Silva et al, 2020) and then adjusted post-hoc, until the electromyographic (EMG) activity recorded from a selected target muscle satisfies standard latency and amplitude requirements (Rossini et al, 2015). Hence, despite the potential confound represented by changes in the excitability of spinal motor neurons, EMG waves as a real-time feedback have been the fundamental guide for titrating TMS in research, diagnostic and treatment protocols.…”

Comparison of hemodynamic changes after repetitive transcranial magnetic stimulation over the anatomical hand knob and hand motor hotspot: A functional near-infrared spectroscopy study

“…Channel 24 was located between C2 and C4 in the international 10/20 system and corresponded to (x = 42, y = – 21, z = 62) in MNI co-ordinates ( Morais et al, 2018 ). This channel was considered the primary motor cortical region related to hand movement among the four ROI channels, as the MRI study reported that the M1-Hand region was located between C2 and C4 ( Silva, Silva, Lira-Bandeira, Costa-Ribeiro, & Araújo-Neto, 2020 ). The results of this study give insight for selecting the target site for neuromodulation of stroke patients.…”

“…ordinates (Morais et al, 2018). This channel was considered the primary motor cortical region related to hand movement among the four ROI channels, as the MRI study reported that the M1-Hand region was located between C2 and C4 (Silva, Silva, Lira-Bandeira, Costa-Ribeiro, & Araújo-Neto, 2020 (Scholkmann, Gerber, Wolf, & Wolf, 2013). However, we could not apply this in our study due to a lack of short SDS 511 signals.…”

Increasing Motor Cortex Activation During Grasping Via Novel Robotic Mirror Hand Therapy: A Pilot fNIRS Study

“…showed the highest activation (Fig. 8), which are located around C4 (or C3) that is known to be the area responsible for hand movement [36]. MT induced activation on both sides, but stronger activation on ipsilateral hemisphere to the robotic glove, which is contralateral to the hand executing the pinch movements.…”