title: The contribution of pre-stimulus neural oscillatory activity to spontaneous response time variability.
abstract: Large variability between individual response times, even in identical conditions, is a ubiquitous property of animal behavior. However, the origins of this stochasticity and its relation to action decisions remain unclear. Here we focus on the state of the perception-action network in the pre-stimulus period and its influence on subsequent saccadic response time and choice in humans. We employ magnetoencephalography (MEG) and a correlational source reconstruction approach to identify the brain areas where pre-stimulus oscillatory activity predicted saccadic response time to visual targets. We find a relationship between future response time and pre-stimulus power, but not phase, in occipital (including V1), parietal, posterior cingulate and superior frontal cortices, consistently across alpha, beta and low gamma frequencies, each accounting for between 1 and 4% of the RT variance. Importantly, these correlations were not explained by deterministic sources of variance, such as experimental factors and trial history. Our results further suggest that occipital areas mainly reflect short-term (trial to trial) stochastic fluctuations, while the frontal contribution largely reflects longer-term effects such as fatigue or practice. Parietal areas reflect fluctuations at both time scales. We found no evidence of lateralization: these effects were indistinguishable in both hemispheres and for both saccade directions, and non-predictive of choice - a finding with fundamental consequences for models of action decision, where independent, not coupled, noise is normally assumed.
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff CF10 3AT, UK; INSERM, U1028, CNRS, UMR5292, Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, Hopital du Vinatier, 95 Boulevard Pinel, Bron, 69500, France. Electronic address: aline.bompas@gmail.com.
authors.forename: Aline
authors.initials: A
authors.lastname: Bompas
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Petroc
authors.initials: P
authors.lastname: Sumner
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff CF10 3AT, UK; School of Pharmacy and Psychology, Auckland University, Private Bag 92019, Auckland, New Zealand.
authors.forename: Suresh D
authors.initials: SD
authors.lastname: Muthumumaraswamy
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Krish D
authors.initials: KD
authors.lastname: Singh
authors.affiliation: School of Experimental Psychology, University of Bristol, 12A Priory Road, Bristol BS7 8SW, UK.
authors.forename: Iain D
authors.initials: ID
authors.lastname: Gilchrist
mesh_terms: D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D013269:Stochastic Processes; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Amplitude; Decision; Free choice; MEG; Phase; Saccades