Task-relevancy effects on movement-related gating are modulated by continuous theta-burst stimulation of the dorsolateral prefrontal cortex and primary somatosensory cortex

Abstract

Movement-related gating ensures that decreased somatosensory information from external stimulation reaches the cortex during movement when compared to resting levels; however, gating may be influenced by task-relevant manipulations, such that increased sensory information ascends to the cortex when information is relevant to goal-based actions. These task-relevancy effects are hypothesized to be controlled by a network involving the dorsolateral prefrontal cortex (DLPFC) based on this region's known role in selective attention, modulating the primary somatosensory cortex (S1). The purpose of the current study was first to verify task-relevancy influences on movement-related gating in the upper limb, and second to test the contribution of the DLPFC and the primary somatosensory cortex (S1) to these relevancy effects. Ten healthy participants received median nerve stimulation at the left wrist during three conditions: rest, task-irrelevant movement, and task-relevant movement. Cortical responses to median nerve stimulations were measured in the form of somatosensory evoked potentials (SEPs). The three conditions were collected on a baseline day and on two separate days following continuous theta-burst (cTBS), which transiently reduces cortical excitability, over either the contralateral S1 or DLPFC. Results demonstrated a significant interaction between stimulation and condition, with a priori contrasts revealing that cTBS over either S1 or DLPFC diminished the relevancy-based modulation of SEP amplitudes; however, the degree of this effect was different. These results indicate that DLPFC influences over S1 are involved in the facilitation of relevant sensory information during movement.

Experimental muscle hyperalgesia modulates sensorimotor cortical excitability, which is partially altered by unaccustomed exercise

“…Therefore the N30 component has been related to the functionality of a complex cortico/subcortical loop linking ganglia, thalamus, supplementary and pre-motor areas [7]. The results of the current study showed for the first time that muscle soreness induced by NGF is able to decrease frontal cortical evoked potentials, suggesting that muscle soreness may interfere with some aspects of motor planning or motor execution.…”

Practice changes beta power at rest and its modulation during movement in healthy subjects but not in patients with Parkinson's disease

“…This ability to filter incoming sensory information during movement has been sometimes referred to as “movement‐related gating”, a particular case of the more general phenomenon of “sensory gating” (Brown et al. ). In this context, beta ERD would reflect, concomitantly, activation of the motor areas and attenuation of the sensory afferences during movement; beta ERS instead, would reflect postmovement reactivation of somatosensory areas that, in turn, would induce inhibition or idle state of the motor areas.…”

“… Brown et al. ). Thus, in the case of sensory or sensorimotor integration deficits, one should expect a dysregulation of such balance and, thus, an alteration of beta ERS and ERD patterns.…”

“…Along this line, there is evidence suggesting that modulation of beta power could be related to the amplitude of somatosensory evoked potentials components representing sensorimotor integration (Rossi et al 2002;Cebolla and Cheron 2015). Such early components are suppressed during active, passive and observed movements (Abbruzzese et al1981;Rushton et al 1981Brown et al 2015. Thus, in the case of sensory or sensorimotor integration deficits, one should expect a dysregulation of such balance and, thus, an alteration of beta ERS and ERD patterns.…”

“…Rather, as suggested by previous studies (Shimazu et al 1999;Cassim et al 2000), it may support a more global function, such as the regulation of sensory and motor interactions during different phases of movement planning and execution. This ability to filter incoming sensory information during movement has been sometimes referred to as "movement-related gating", a particular case of the more general phenomenon of "sensory gating" (Brown et al 2015). In this context, beta ERD would reflect, concomitantly, activation of the motor areas and attenuation of the sensory afferences during movement; beta ERS instead, would reflect postmovement reactivation of somatosensory areas that, in turn, would induce inhibition or idle state of the motor areas.…”