The Impact of Ongoing Brain Activity on the Variability of Human Brain Function and Behaviour

Perceptual decisions can be made when sensory input affords an inference about what generated that input. Here, wereport findings from two independent perceptual experiments conducted during functional magnetic resonance imaging(fMRI) with a sparse event-related design. The first experiment, in the visual modality, involved forced-choice discriminationof coherence in random dot kinematograms that contained either subliminal or periliminal motion coherence. The secondexperiment, in the auditory domain, involved free response detection of (non-semantic) near-threshold acoustic stimuli. Weanalysed fluctuations in ongoing neural activity, as indexed by fMRI, and found that neuronal activity in sensory areas(extrastriate visual and early auditory cortex) biases perceptual decisions towards correct inference and not towards aspecific percept. Hits (detection of near-threshold stimuli) were preceded by significantly higher activity than both misses ofidentical stimuli or false alarms, in which percepts arise in the absence of appropriate sensory input. In accord withpredictive coding models and the free-energy principle, this observation suggests that cortical activity in sensory brain areasreflects the precision of prediction errors and not just the sensory evidence or prediction errors per se. Citation: Hesselmann G, Sadaghiani S, Friston KJ, Kleinschmidt A (2010) Predictive Coding or Evidence Accumulation? False Inference and NeuronalFluctuations. PLoS ONE 5(3): e9926. doi:10.1371/journal.pone.0009926 Editor: Jan Lauwereyns, Kyushu University, Japan Received November 25, 2009; Accepted March 9, 2010; Published March 29, 2010 Copyright: 2010 Hesselmann et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permitsunrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This fMRI experiment was part of a general research program on functional neuroimaging of the human brain which was sponsored by the AtomicEnergy Commission (principal investigator Denis Le Bihan). This work was funded by the Agence Nationale de la Recherche (SPONTACT; France). S.S. is supportedby the Friedrich-Ebert Foundation (Germany). G.H. is supported by a Minerva fellowship (Max Planck Society). The funders had no role in study design, datacollection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] . These authors contributed equally to this work.