Strengthening connectivity between premotor and motor cortex increases inter-areal communication in the human brain

Abstract

The ventral premotor cortex (PMv) is an important component of cortico-cortical pathways mediating prefrontal control over primary motor cortex (M1) function. Paired associative stimulation (ccPAS) is known to change PMv influence over M1 in humans, which manifests differently depending on the behavioural context. Here we show that these changes in influence are functionally linked to PMv-M1 phase synchrony changes induced by repeated paired stimulation of the two areas. PMv-to-M1 ccPAS leads to increased phase synchrony in alpha and beta bands while reversed order M1-to-PMv ccPAS leads to decreased theta phase synchrony. These changes are visible at rest but they are predictive of changes in oscillatory power in the same frequencies during movement execution and inhibition, respectively. The results unveil a link between the physiology of the motor network and the resonant frequencies mediating its interactions, and provide a putative mechanism underpinning the relationship between synaptic efficacy and brain oscillations.

Top-down and bottom-up interactions rely on nested brain oscillations

“…Sensor differences with z-values corresponding to p<0.05 were retained as significant. The connectivity index of each condition was then estimated using the formula: CI = sig_pos/ sp_total, where sig_pos are connections that are significantly higher after FEF-TMS with respect to M1foot-TMS, and sp_tot are all possible connections (68,69). Furthermore, another permutation test was introduced to calculate the significance threshold for CI.…”

Modulation of dorsal premotor cortex disrupts neuroplasticity of primary motor cortex in young and older adults

“…For example, recent work assessing variability of M1 iTBS has suggested that the ability of iTBS to engage neural oscillations in the β range (13-30 Hz) may be an important predictor of the neuroplastic response to iTBS (Leodori et al, 2021). Enhancing premotor-M1 communication using cortico-cortical paired associated stimulation (ccPAS) has been recently shown to improve the synchronisation of neural oscillations (which is thought to mediate neuronal communication and plasticity) in the β range (Trajkovic et al, 2023).…”

Applications of cortico‐cortical paired associative stimulation for age‐related declines of hand function

“…PMv activity is necessary for various grasping movements, exerting a substantial excitatory or inhibitory influence on M1 during these actions (Casarotto, Dolfini, Fadiga et al., 2023). Previous research has demonstrated that the PMv to M1 pathway is important for movement planning and control, and this inter‐areal communication can be modulated by ccPAS interventions with stimulation applied to PMv 6–8 ms prior to M1 (Sel, 2021; Trajkovic, 2023). Related to the findings by Trajkovic et al.…”

“…and Sel et al., Casarotto et al. recently demonstrated that the direction of TMS current over M1 (A‐P or P‐A) during ccPAS can affect post‐intervention measures (Casarotto, Dolfini, Cardellicchio et al., 2023; Sel et al., 2021; Trajkovic et al., 2023).…”

“…and Sel et al. indicate that the temporal and spatial direction of PMv and M1 ccPAS can be manipulated to preferentially modify cortico‐cortical networks for functional outcomes (Casarotto, Dolfini, Fadiga et al., 2023; Casarotto, Dolfini, Cardellicchio et al., 2023; Sel et al., 2021; Trajkovic et al., 2023).…”