TY - JOUR T1 - Human self-initiated action is preceded by a reliable process of noise reduction JF - bioRxiv DO - 10.1101/120105 SP - 120105 AU - Nima Khalighinejad AU - Aaron Schurger AU - Andrea Desantis AU - Leor Zmigrod AU - Patrick Haggard Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/03/24/120105.abstract N2 - A gradual buildup of electrical potential over motor areas precedes self-initiated movements. These “readiness potentials” (RPs) could simply reflect stochastic fluctuations in neural activity. We operationalised self-initiated actions as endogenous ‘skip’ responses while waiting for target stimuli in a perceptual decision task. Across-trial variability of EEG decreased more markedly prior to self-initiated compared to externally-triggered skip actions. This convergence towards a fixed pattern suggests a consistent preparatory process prior to self-initiated action. A leaky stochastic accumulator model could reproduce these features of the data, given the additional assumption of a decrease in noise level at the input to the accumulator prior to self-initiated, but not externally-triggered actions. The assumed reduction in neural noise was supported by analyses of both within-trial EEG variability and of spectral power. We suggest that a process of noise reduction is consistently recruited prior to self-initiated action. This precursor event may underlie the emergence of RP. ER -