Spontaneous EEG fluctuations determine the readiness potential: is preconscious brain activation a preparation process to move?


It has been repeatedly shown that specific brain activity related to planning movement develops before the conscious intention to act. This empirical finding strongly challenges the notion of free will. Here, we demonstrate that in the Libet experiment, spontaneous fluctuations of the slow electro-cortical potentials (SCPs) account for a significant fraction of the readiness potential (RP). The individual potential shifts preceding self-initiated movements were classified as showing a negative or positive shift. The negative and positive potential shifts were analyzed in a self-initiated movement condition and in a no-movement condition. Comparing the potential shifts between both conditions, we observed no differences in the early part of the potential. This reveals that the apparently negative RP emerges through an unequal ratio of negative and positive potential shifts. These results suggest that ongoing negative shifts of the SCPs facilitate self-initiated movement but are not related to processes underlying preparation or decision to act.

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  1. Bennett MR, Hacker PMS (2003) Philosophical foundations of neuroscience. Wiley-Blackwell, Oxford

  2. Birbaumer N, Elbert T, Canavan AGM, Rockstroh B (1990) Slow potential of the cerebral cortex and behavior. Physiol Rev 70(1):1–41

    PubMed  CAS  Google Scholar 

  3. Delorme A, Makeig S (2004) EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis. J Neurosci Methods 134(1):9–21

    PubMed  Article  Google Scholar 

  4. Guggisberg AG, Mottat AM (2013) Timing and awareness of movement decisions: does consciousness really come too late? Front Hum Neurosci 7:385. doi:10.3389/fnhum.2013.00385

    PubMed  Article  Google Scholar 

  5. Haggard P (2008) Human volition: towards a neuroscience of will. Nat Rev Neurosci 9(12):934–946

    PubMed  Article  CAS  Google Scholar 

  6. Haggard P, Eimer M (1999) On the relation between brain potentials and the awareness of voluntary movements. Exp Brain Res 126(1):128–133

    PubMed  Article  CAS  Google Scholar 

  7. Herrmann CS, Pauen M, Min BK, Busch NA, Rieger JW (2008) Analysis of a choice-reaction task yields a new interpretation of Libet’s experiment. Int J Psychophysiol 67:151–157

    PubMed  Article  Google Scholar 

  8. Keller I, Heckhausen H (1990) Readiness potentials preceding spontaneous motor acts: voluntary vs. involuntary control. Electroencephalogr Clin Neurophysiol 76:351–361

    PubMed  Article  CAS  Google Scholar 

  9. Kornhuber HH, Deecke L (1965) Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: bereitschaftspotential und reafferente Potentiale. Pflügers Archive 284(1):1–17

    Article  CAS  Google Scholar 

  10. Kotchoubey B (2012) Why are you free? Neurobiology and psychology of voluntary action. Nova Sci Pub, New York

    Google Scholar 

  11. Libet B (1985) Unconscious cerebral initiative and the role of conscious will in voluntary action. Behav Brain Sci 8(4):529–566

    Article  Google Scholar 

  12. Libet B, Gleason CA, Wright EW, Pearl DK (1983) Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain 106(3):623–642

    PubMed  Article  Google Scholar 

  13. McCallum WC, Curry SH (1993) Slow potential changes in the human brain. Springer, Berlin

    Book  Google Scholar 

  14. Miller J, Shepherdson P, Trevena J (2011) Effects of clock monitoring on electroencephalographic activity: is unconscious movement intention an artifact of the clock? Psychol Sci 22(1):103–109

    PubMed  Article  Google Scholar 

  15. Mitzdorf U (1985) Current source-density method and application in cat cerebral cortex: investigation of evoked potentials and EEG phenomena. Physiol Rev 65(1):37–100

    PubMed  CAS  Google Scholar 

  16. Rigoni D, Kühn S, Sartori G, Brass M (2011) Inducing disbelief in free will alters brain correlates of preconscious motor preparation: the brain minds whether we believe in free will or not. Psychol Sci 22(5):613–618

    PubMed  Article  Google Scholar 

  17. Schlegel A, Alexander P, Sinnott-Armstrong W, Roskies A, Tse PT, Wheatley T (2013) Braking up the wrong free: readiness potentials reflect processes independent of conscious will. Exp Brain Res 229(3):329–335

    Google Scholar 

  18. Schurger A, Sitt JD, Dehaene S (2012) An accumulator model for spontaneous neural activity prior to self-initiated movement. Proc Natl Acad Sci 109(42):E2904–E2913

    PubMed  Article  CAS  Google Scholar 

  19. Shibasaki H, Hallet M (2006) What is the bereitschaftspotential? Clin Neurophysiol 117(11):2341–2356

    PubMed  Article  Google Scholar 

  20. Sirigui A, Daprati E, Ciancia S, Giraux P, Nighoghossian N, Posada A, Haggard P (2004) Altered awareness of voluntary action after damage to the parietal cortex. Nat Neurosci 7(1):80–84

    Article  Google Scholar 

  21. Trevena J, Miller J (2010) Brain preparation before a voluntary action: evidence against unconscious movement initiation. Conscious Cogn 19:447–456

    PubMed  Article  Google Scholar 

  22. VaezMousavi SM, Barry RJ (1993) Positive and negative shifts of the readiness potential: preparatory effects. Int J Psychophysiol 15(2):105–113

    PubMed  Article  CAS  Google Scholar 

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Correspondence to Stefan Schmidt.

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Jo, HG., Hinterberger, T., Wittmann, M. et al. Spontaneous EEG fluctuations determine the readiness potential: is preconscious brain activation a preparation process to move?. Exp Brain Res 231, 495–500 (2013). https://doi.org/10.1007/s00221-013-3713-z

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  • Free will
  • Intention to move
  • Libet experiment
  • Slow cortical potential
  • Readiness potential