Better Get Back to Work: A Role for Motor Beta Desynchronization in Incentive Motivation

Abstract

Much research has been devoted to characterizing brain representations of reward and movement. However, the mechanisms allowing expected rewards to influence motor commands remain poorly understood. Unraveling such mechanisms is crucial to providing explanations of how behavior can be driven by goals, hence accounting for apathy cases in clinics. Here, we propose that the reduction of motor beta synchrony (MBS) before movement onset could participate in this incentive motivation process. To test this hypothesis, we recorded brain activity using magnetoencenphalography (MEG) while human participants were exerting physical effort to win monetary incentives. Knowing that the payoff was proportional to the time spent above a target force, subjects spontaneously took breaks when exhausted and resumed effort production when repleted. Behavioral data indicated that the rest periods were shorter when higher incentives were at stake. MEG data showed that the amplitude of MBS reduction correlated to both incentive level and rest duration. Moreover, the time of effort initiation could be predicted by MBS reduction measured at the beginning of rest periods. Incentive effects on MBS reduction and rest duration were also correlated across subjects. Finally, Bayesian comparison between possible causal models suggested that MBS reduction mediates the impact of incentive level on rest duration. We conclude that MBS reduction could represent a neural mechanism that speeds the initiation of effort production when the effort is more rewarded.

Beta-band activity and connectivity in sensorimotor and parietal cortex are important for accurate motor performance

“…Cortical beta amplitude has been studied as a crucial factor that regulates motor performance within and between trials (Boonstra et al, 2007; Gilbertson et al, 2005; Meyniel and Pessiglione, 2014; Serrien and Brown, 2003; Tan et al, 2014). For instance, Lin and colleagues (2012) compared haptic feedback to non-haptic feedback in a visuomotor tracking task and found haptic feedback results in less tracking error with desynchronization in beta-band of the right occipital cortex.…”

Single trial beta oscillations index time estimation

“…However, the reanalysis of this data set, together with the results of Bartolo et al (2014), demonstrate that beta power at trial onset index timing performance, suggesting that timing mechanisms (e.g., motor inhibition) typically not considered in the theories of interval timing may be important in time production. Interestingly, recent work has linked the notion of inhibition, beta power, and dopamine level in the nigrostratal pathway, proposing that the dopamine level can be traced by beta power fluctuations Brown, 2011, also see Meyniel andPessiglione, 2014). Within this framework, larger beta power is caused by a low level of dopamine: An increase in beta power is signaling the maintenance of a status quo in the sensorimotor system (Engel and Fries, 2010) whereas a decrease of beta power in the cortical-basal ganglia system increases the likelihood for a new action (Jenkinson and Brown, 2011).…”

How the Brain Decides When to Work and When to Rest: Dissociation of Implicit-Reactive from Explicit-Predictive Computational Processes

“…Such preparation is reflected by motor signals such as the readiness potential [29], [30] or the de-synchronization of beta oscillations [31], [32]. We showed in a previous publication [33] that the last process is modulated by incentive level; it could therefore mediate the effect of motivation on cost dissipation in the posterior insula. Second, the dissipation of cost evidence could be accentuated by analgesic mechanisms.…”