Differential Influence of the Dorsal Premotor and Primary Somatosensory Cortex on Corticospinal Excitability during Kinesthetic and Visual Motor Imagery: A Low-Frequency Repetitive Transcranial Magnetic Stimulation Study

Abstract

Consistent evidence suggests that motor imagery involves the activation of several sensorimotor areas also involved during action execution, including the dorsal premotor cortex (dPMC) and the primary somatosensory cortex (S1). However, it is still unclear whether their involvement is specific for either kinesthetic or visual imagery or whether they contribute to motor activation for both modalities. Although sensorial experience during motor imagery is often multimodal, identifying the modality exerting greater facilitation of the motor system may allow optimizing the functional outcomes of rehabilitation interventions. In a sample of healthy adults, we combined 1 Hz repetitive transcranial magnetic stimulation (rTMS) to suppress neural activity of the dPMC, S1, and primary motor cortex (M1) with single-pulse TMS over M1 for measuring cortico-spinal excitability (CSE) during kinesthetic and visual motor imagery of finger movements as compared to static imagery conditions. We found that rTMS over both dPMC and S1, but not over M1, modulates the muscle-specific facilitation of CSE during kinesthetic but not during visual motor imagery. Furthermore, dPMC rTMS suppressed the facilitation of CSE, whereas S1 rTMS boosted it. The results highlight the differential pattern of cortico-cortical connectivity within the sensorimotor system during the mental simulation of the kinesthetic and visual consequences of actions.

The recruitment of indirect waves within primary motor cortex during motor imagery: A directional transcranial magnetic stimulation study

“…Although this remains speculative, the facilitatory input from PMd to M1 during MI has decreased the SICI level within M1. Moreover, the opposite higher level of SICI during MI (vs. rest) observed with PA current reflect the activation of inhibitory inputs received from the somatosensory cortex and the supplementary motor area, both areas known to functionally inhibit M1 when imagining (Kasess et al, 2008; Oldrati et al, 2021). Finally, it is also possible that the cerebellum, which facilitates M1 excitability during MI (Rannaud Monany et al, 2022; Tanaka et al, 2018), also contributes to the result of the current study because the influence of the cerebellum on M1 might occur via interactions with specific I‐waves generating circuits (Spampinato et al, 2020).…”

“…For example, late I‐waves evoked by AP orientation could activate axons of neurons of the premotor cortex projecting to the corticospinal cells (Aberra et al, 2020; Desmons et al, 2021; Groppa et al, 2012; Siebner, 2020; Volz et al, 2015). Recently, Oldrati et al (2021) reported that following off‐line 1‐Hz inhibitory repetitive TMS over the dorsal premotor cortex (PMd), corticospinal excitability assessed during kinesthetic MI was not significantly higher than rest condition (Oldrati et al, 2021). These findings suggest facilitatory connectivity from PMd to M1 during MI.…”

The recruitment of indirect-waves within primary motor cortex during motor imagery: A directional Transcranial Magnetic Stimulation study

“…For example, late I-waves evoked by AP orientation could activate axons of neurons of the premotor cortex projecting to the corticospinal cells (Groppa et al ., 2012; Volz et al ., 2015; Aberra et al ., 2020; Siebner, 2020; Desmons et al ., 2021). Recently, Oldrati et al (2021) reported that following offline 1Hz inhibitory repetitive TMS over the dorsal premotor cortex (PMd), corticospinal excitability assessed during kinesthetic MI was not significantly higher than rest condition (Oldrati et al ., 2021). These findings suggest a facilitatory connectivity from PMd to M1 during MI.…”

“…Although this remains speculative, it is possible that the facilitatory input from PMd to M1 occurring during MI has decreased the SICI level within M1. Moreover, the opposite higher level of SICI during MI (vs. rest) observed with PA current reflect the activation of inhibitory inputs received from somatosensory cortex and SMA, both areas known to functionally inhibit M1 when imagining (Kasess et al ., 2008; Oldrati et al ., 2021). Finally, it is also possible that cerebellum, which facilitates M1 excitability during MI (Tanaka et al ., 2018; Monany et al ., 2021), also contributes to the result of the current study since the influence of cerebellum on M1 might occur via interactions with specific I-waves generating circuits (Spampinato et al ., 2020).…”

Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex Increases Posterior Theta Rhythm and Reduces Latency of Motor Imagery

“…These findings suggest that the SMA contributes to MI by coordinating and planning motor sequences. Furthermore, TMS studies have revealed that stimulating the dorsal premotor cortex (PMd) during MI tasks can modulate corticospinal excitability [ 42 , 43 ]. This shows that the PMd is involved in motor planning and execution processes during MI.…”