Movement gating of beta/gamma oscillations involved in the N30 somatosensory evoked potential

Abstract

Evoked potential modulation allows the study of dynamic brain processing. The mechanism of movement gating of the frontal N30 component of somatosensory evoked potentials (SEP) produced by the stimulation of the median nerve at wrist remains to be elucidated. At rest, a power enhancement and a significant phase-locking of the electroencephalographic (EEG) oscillation in the beta/gamma range (25-35 Hz) are related to the emergence of the N30. The latter was also perfectly identified in presence of pure phase-locking situation. Here, we investigated the contribution of these rhythmic activities to the specific gating of the N30 component during movement. We demonstrated that concomitant execution of finger movement of the stimulated hand impinges such temporal concentration of the ongoing beta/gamma EEG oscillations and abolishes the N30 component throughout their large topographical extent on the scalp. This also proves that the phase-locking phenomenon is one of the main actors for the N30 generation. These findings could be explained by the involvement of neuronal populations of the sensorimotor cortex and other related areas, which are unable to respond to the phasic sensory activation and to phase-lock their firing discharges to the external sensory input during the movement. This new insight into the contribution of phase-locked oscillation in the emergence of the N30 and in its gating behavior calls for a reappraisal of fundamental and clinical interpretation of the frontal N30 component.

Sensorimotor and cognitive involvement of the beta–gamma oscillation in the frontal N30 component of somatosensory evoked potentials

“…Such additional proprioceptive information might refer to the coding of precise kinesthetic aspects of the observed movement and other body schema information, related to the preservation of body identity (Iacoboni et al, 1999). The similar localization in the motor cortex of the gamma phase locking, both at rest and during hand movement observation at the latency of the N30 component, reinforced previous findings, which suggested that gamma phase locking is the main mechanism underlying the N30 component, while gamma ERS might indicate a modulating role reflecting multimodal integration (Cebolla et al, 2009(Cebolla et al, , 2014.…”

“…While the earlier thalamic P14 and the parietal N20 remain stable, the N30 amplitude is highly sensitive to concurrent input from the periphery, such as superficial and deep muscle massage (Cheron and Borenstein, 1991) or centrally generated as motor execution, motor preparation and movement imagery (Rushton et al, 1981;Cheron andBorenstein, 1987, 1992;Rossini et al, 1999). Within the framework of the oscillatory approach, it has been demonstrated that when flexing the fingers of the stimulated hand, the phase consistency of the beta-gamma oscillations, identifiable when the stimulation was given at rest, was impinged (Cebolla et al, 2009). At precisely that point, the abolition of the N30 component was observed throughout its wide topographical distribution on the scalp.…”

“…It was proposed that the neuronal circuits that generate the N30 component might be principally involved in movement execution. For that reason, such cortical areas would be unable to respond effectively to the sensorimotor activation related to movement and simultaneously phase-lock their firing discharges to the external electrical somatosensory stimulation, delivered during the movement (Cebolla et al, 2009) (Fig. 2).…”

“…Similarly, phase rearrangement of single beta-gamma EEG trials occurred only at rest (C versus G). Adapted figure from Cebolla et al (2009). License for reuse has been obtained.…”

Somatosensory input to non-primary motor areas is enhanced during preparation of cued contraterlateral finger sequence movements

“…Importantly, abnormal sensory gating has been N30 is gated during preparation, execution or imagination of movements to the same limb as MN stimulation (i.e. ipsilateral movements) [3][4][5][6][7][8][9][10][11][12][13][14]. In contrast, previous research has also shown that N30 peaks are enhanced during the execution of contralateral repetitive finger-to-thumb opposition movements [15] and during self-paced gripping [8].…”