The effect of salient stimuli on neural oscillations, isometric force, and their coupling

Abstract

Survival in a suddenly-changing environment requires animals not only to detect salient stimuli, but also to promptly respond to them by initiating or revising ongoing motor processes. We recently discovered that the large vertex brain potentials elicited by sudden supramodal stimuli are strongly coupled with a multiphasic modulation of isometric force, a phenomenon that we named cortico-muscular resonance (CMR). Here, we extend our investigation of the CMR to the time-frequency domain. We show that (i) both somatosensory and auditory stimuli evoke a number of phase-locked and non-phase-locked modulations of EEG spectral power. Remarkably, (ii) some of these phase-locked and non-phase-locked modulations are also present in the Force spectral power. Finally, (iii) EEG and Force time-frequency responses are correlated in two distinct regions of the power spectrum. An early, low-frequency region (∼4 Hz) reflects the previously-described coupling between the phase-locked EEG vertex potential and force modulations. A late, higher-frequency region (beta-band, ∼20 Hz) reflects a second coupling between the non-phase-locked increase of power observed in both EEG and Force. In both time-frequency regions, coupling was maximal over the sensorimotor cortex contralateral to the hand exerting the force, suggesting an effect of the stimuli on the tonic corticospinal drive. Thus, stimulus-induced CMR occurs across at least two different types of cortical activities, whose functional significance in relation to the motor system should be investigated further. We propose that these different types of corticomuscular coupling are important to alter motor behaviour in response to salient environmental events.

Electrophysiological correlates of focused attention on low- and high-distressed tinnitus

“…one’s own body), the state of concentrating on bothersome tinnitus produces higher beta activity. Increased high-frequency oscillations have been found in response to salient or unpleasant stimuli [ 81 , 82 ]. Moreover, beta rhythm is thought to be associated with stress and anxiety [ 83 ] as well as concentration and arousal [ 84 , 85 ].…”

Latency and amplitude of the stop-signal P3 event-related potential are related to inhibitory GABAaactivity in primary motor cortex

“…Given the recency of these findings, theoretical developments and empirical studies are still ongoing in this domain. However, it is notable that low-latency reductions of motor cortex such as the above described (including MEP suppression at 150ms following the stimulus) are found not just after stop-signals, but indeed after any sort of surprising (Dutra, Waller, & Wessel, 2018; G Novembre et al, 2018; Giacomo Novembre et al, 2019; Wessel & Aron, 2013) or even merely infrequent events (Iacullo, Diesburg, & Wessel, 2020). This could suggest that instead of a single, monolithic mechanism, stopping is implemented by a multi-step sequence of inhibitory processes, similar to what was proposed in the “pause-then-cancel” model by Schmidt, Berke and colleagues (Schmidt & Berke, 2017; Schmidt et al, 2013).…”

Towards a Unified Neural Mechanism for Reactive Adaptive Behaviour

“…The term Cortico-Muscular Resonance (CMR) has been recently proposed to refer to a series of fast modulations of muscular activity evoked by sudden sensory stimuli, irrespectively of their sensory modality (5,6).…”

“…CMR has been observed using both electromyography (EMG) and force measurements. In a typical experiment, participants are required to exert a constant isometric force on a transducer held between the index finger and thumb, while simple, task-irrelevant and fast-rising sensory stimuli (either auditory or somatosensory) are delivered (5,6) (Fig. 1a).…”