On why the unconscious prerequisites and consequences of consciousness might derail us from unraveling the neural correlates of consciousness
Jaan Aru | Frankfurt Institute for Advanced Studies, Frankfurt am Main
Wolf Singer | Ernst Strüngmann Institute in Cooperation with Max Planck Society, Frankfurt am Main
It has been proposed that one key step for solving the mystery of consciousness is to locate the neural correlates of consciousness (NCC). The experimental paradigms for revealing the NCC have commonly applied the contrast between conditions with and without conscious perception. However, such contrast does not exclusively reveal the neural processes directly related to conscious experience of the target but also the prerequisites for and the consequences of conscious perception. Therefore, understanding the neural bases of conscious experience requires the NCC to be experimentally disentangled from these confounding processes. Here we review some recent experimental developments and suggest some new empirical approaches for distilling the neural basis of conscious perception.
References (65)
Aedo-Jury, F., Schwiedrzik, C.M., Singer, W., & Melloni, L. (2010, November). Differential brain activation for increases in objective performance and subjective awareness in perceptual learning. Paper presented at the 40th Annual Meeting of the Society for Neuroscience (SfN), San Diego, USA.
Aru, J., Axmacher, N., Do Lam, A.T.A., Fell, J., Elger, C.E., Singer, W., & Melloni, L. (2012). Local category-specific gamma band responses in the visual cortex do not reflect conscious perception. Journal of Neuroscience, 32(43), 14909–14914.
Aru, J., & Bachmann, T. (2009a). Boosting up gamma-band oscillations leaves target-stimulus in masking out of awareness: Explaining an apparent paradox. Neuroscience Letters, 450(3), 351–355.
Aru, J., & Bachmann, T. (2009b). Occipital EEG correlates of conscious awareness when subjective target shine-through and effective visual masking are compared: Bifocal early increase in gamma power and speed-up of P1. Brain Research, 1271, 60–73.
Aru, J., Bachmann, T., Singer, W., & Melloni, L. (2012). Distilling the neural correlates of consciousness. Neuroscience & Biobehavioral Reviews, 36(2), 737–746.
Auksztulewicz, R., & Blankenburg, F. (2013). Subjective rating of weak tactile stimuli is parametrically encoded in event-related potentials. Journal of Neuroscience, 33(29), 11878–11887.
Baars, B.J. (1997). In the theatre of consciousness: The workspace of the mind. New York: Oxford University Press.
Bachmann, T. (2009). Finding ERP-signatures of target awareness: Puzzle persists because of experimental co-variation of the objective and subjective variables. Consciousness and Cognition, 18(3), 804–808.
Bachmann, T., Breitmeyer, B.G., & Öğmen, H. (2011). Experimental phenomena of consciousness: A brief dictionary (Rev. ed.). New York: Oxford University Press.
Bachmann, T., & Francis, G. (2014). Visual masking: Studying perception, attention, and consciousness. Oxford, UK: Academic Press.
Bar, M., Tootell, R.B.H., Schacter, D.L., Greve, D.N., Fischl, B., Mendola, J.D., Rosen, B.R., & Dale, A.M. (2001). Cortical mechanisms specific to explicit visual object recognition. Neuron, 29(2), 529–535.
Brown, J.W. (1988). The life of the mind: Selected papers. Hillsdale, NJ: Lawrence Erlbaum Associates.
Christensen, M.S., Ramsøy, T.Z., Lund, T.E., Madsen, K.H., & Rowe, J.B. (2006). An fMRI study of the neural correlates of graded visual perception. Neuroimage, 31(4), 1711–1725.
Crick, F., & Koch, C. (1990). Towards a neurobiological theory of consciousness. Seminars in the Neurosciences, 2, 263–275.
Davidesco, I., Zion-Golumbic, E., Bickel, S., Harel, M., Groppe, D.M., Keller, C.J., Schevon, C.A., McKhann, G.M., Goodman, R.R., Goelman, G., Schroeder, C.E., Mehta, A.D., & Malach, R. (2014). Exemplar selectivity reflects perceptual similarities in the human fusiform cortex. Cerebral Cortex, 24(7), 1879–1893.
de Graaf, T.A., Hsieh, P.-J., & Sack, A.T. (2012). The ‘correlates’ in neural correlates of consciousness. Neuroscience & Biobehavioral Reviews, 36(1), 191–197.
Dehaene, S., & Changeux, J.-P. (2011). Experimental and theoretical approaches to conscious processing. Neuron, 70(2), 200–227.
Dehaene, S., Changeux, J.-P., Naccache, L., Sackur, J., & Sergent, C. (2006). Conscious, preconscious, and subliminal processing: A testable taxonomy. Trends in Cognitive Sciences, 10(5), 204–211.
Dehaene, S., & Naccache, L. (2001). Towards a cognitive neuroscience of consciousness: Basic evidence and a workspace framework. Cognition, 79(1–2), 1–37.
Del Cul, A., Baillet, S., & Dehaene, S. (2007). Brain dynamics underlying the nonlinear threshold for access to consciousness. PLoS Biology, 5(10), e260.
Field, G.D., Sampath, A.P., & Rieke, F. (2005). Retinal processing near absolute threshold: From behavior to mechanism. Annual Review of Physiology, 67, 491–514.
Fisch, L., Privman, E., Ramot, M., Harel, M., Nir, Y., Kipervasser, S., Andelman, F., Neufeld, M.Y., Kramer, U., Fried, I., & Malach, R. (2009). Neural “ignition”: Enhanced activation linked to perceptual awareness in human ventral stream visual cortex. Neuron, 64(4), 562–574.
Gaillard, R., Dehaene, S., Adam, C., Clémenceau, S., Hasboun, D., Baulac, M., Cohen, L., & Nacchache, L. (2009). Converging intracranial markers of conscious access. PLoS Biology, 7(3), e61.
Haushofer, J., Livingstone, M.S., & Kanwisher, N. (2008). Multivariate patterns in object-selective cortex dissociate perceptual and physical shape similarity. PLoS Biology, 6(7), e187.
Haynes, J.-D. (2009). Decoding visual consciousness from human brain signals. Trends in Cognitive Sciences, 13(5), 194–202.
Haynes, J.-D., Driver, J., & Rees, G. (2005). Visibility reflects dynamic changes of effective connectivity between V1 and fusiform cortex. Neuron, 46(5), 811–821.
Horikawa, T., Tamaki, M., Miyawaki, Y., & Kamitani, Y. (2013). Neural decoding of visual imagery during sleep. Science, 340(6132), 639–642.
Jannati, A., & Di Lollo, V. (2012). Relative blindsight arises from a criterion confound in metacontrast masking: Implications for theories of consciousness. Consciousness and Cognition, 21(1), 307–314.
Kahneman, D. (1968). Method, findings, and theory in studies of visual masking. Psychological Bulletin, 70(6), 404–425.
Kammer, T. (1999). Phosphenes and transient scotomas induced by magnetic stimulation of the occipital lobe: Their topographic relationship. Neuropsychologia, 37(2), 191–198.
Koch, C. (2004). The quest for consciousness: A neurobiological approach. Englewood, CO: Roberts & Company.
Koivisto, M., & Revonsuo, A. (2008). Comparison of event-related potentials in attentional blink and repetition blindness. Brain Research, 1189, 115–126.
Koivisto, M., & Revonsuo, A. (2010). Event-related brain potential correlates of visual awareness. Neuroscience & Biobehavioral Reviews, 34(6), 922–934.
Lamme, V.A.F. (2006). Towards a true neural stance on consciousness. Trends in Cognitive Sciences, 10(11), 494–501.
Lamy, D., Salti, M., & Bar-Haim, Y. (2009). Neural correlates of subjective awareness and unconscious processing: An ERP study. Journal of Cognitive Neuroscience, 21(7), 1435–1446.
Lau, H.C. (2008). A higher order Bayesian decision theory of consciousness. Progress in Brain Research, 168, 35–48.
Malach, R. (2007). The measurement problem in consciousness research. Behavioral and Brain Sciences, 30(5–6), 516–517.
Melloni, L., Molina, C., Pena, M., Torres, D., Singer, W., & Rodriguez, E. (2007). Synchronization of neural activity across cortical areas correlates with conscious perception. Journal of Neuroscience, 27(11), 2858–2865.
Melloni, L., Schwiedrzik, C.M., Müller, N., Rodriguez, E., & Singer, W. (2011). Expectations change the signatures and timing of electrophysiological correlates of perceptual awareness. Journal of Neuroscience, 31(4), 1386–1396.
Miller, S.M. (2001). Binocular rivalry and the cerebral hemispheres: With a note on the correlates and constitution of visual consciousness. Brain and Mind, 2(1), 119–149.
Miller, S.M. (2007). On the correlation/constitution distinction problem (and other hard problems) in the scientific study of consciousness. Acta Neuropsychiatrica, 19(3), 159–176.
Mur, M., Meys, M., Bodurka, J., Goebel, R., Bandettini, P.A., & Kriegeskorte, N. (2013). Human object-similarity judgments reflect and transcend the primate-IT object representation. Frontiers in Psychology, 4, 128.
Pascual-Leone, A., & Walsh, V. (2001). Fast backprojections from the motion to the primary visual area necessary for visual awareness. Science, 292(5516), 510–512.
Pins, D., & ffytche, D. (2003). The neural correlates of conscious vision. Cerebral Cortex, 13(5), 461–474.
Pitts, M.A., Martínez, A., & Hillyard, S.A. (2012). Visual processing of contour patterns under conditions of inattentional blindness. Journal of Cognitive Neuroscience, 24(2), 287–303.
Pitts, M.A., Metzler, S., & Hillyard, S. (2014). Isolating neural correlates of conscious perception from neural correlates of reporting one’s perception. Frontiers in Psychology, 5, 1078.
Pitts, M.A., Padwal, J., Fennelly, D., Martínez, A., & Hillyard, S.A. (2014). Gamma band activity and the P3 reflect post-perceptual processes, not visual awareness. Neuroimage, 101, 337–350.
Postle, B.R. (2009). The hippocampus, memory, and consciousness. In S. Laureys & G. Tononi (Eds.), The neurology of consciousness: Cogntive neuroscience and neuropathology (pp.326–338). Oxford, UK: Elsevier Ltd.
Quiroga, R.Q., Mukamel, R., Isham, E.A., Malach, R., & Fried, I. (2008). Human single-neuron responses at the threshold of conscious recognition. Proceedings of the National Academy of Sciences USA, 105(9), 3599–3604.
Rees, G., Kreiman, G., & Koch, C. (2002). Neural correlates of consciousness in humans. Nature Reviews Neuroscience, 3(4), 261–270.
Revonsuo, A. (2000). Prospects for a scientific research program on consciousness. In T. Metzinger (Ed.), Neural correlates of consciousness: Empirical and conceptual questions (pp.57–75). Cambridge, MA: MIT Press.
Revonsuo, A. (2001). Can functional brain imaging discover consciousness in the brain? Journal of Consciousness Studies, 8(3), 3–23.
Rose, D. (2006). Consciousness: Philosophical, psychological, and neural theories. Oxford, UK: Oxford University Press.
Rousselet, G.A., & Pernet, C.R. (2011). Quantifying the time course of visual object processing using ERPs: It’s time to up the game. Frontiers in Psychology, 2, 107.
Sahraie, A., Trevethan, C.T., MacLeod, M.J., Murray, A.D., Olson, J.A., & Weiskrantz, L. (2006). Increased sensitivity after repeated stimulation of residual spatial channels in blindsight. Proceedings of the National Academy of Sciences USA, 103(40), 14971–14976.
Schwiedrzik, C.M., Jacob, P., Singer, W., & Melloni, L. (2012, October).
Perceptual learning effects on sensitivity and subjective awareness rely on different neural systems
. Paper presented at the 42nd Annual Meeting of the Society for Neuroscience (SfN), New Orleans, USA.
Schwiedrzik, C.M., Ruff, C.C., Lazar, A., Leitner, F.C., Singer, W., & Melloni, L. (2014). Untangling perceptual memory: Hysteresis and adaptation map into separate cortical networks. Cerebral Cortex, 24(5), 1152–1164.
Schwiedrzik, C.M., Singer, W., & Melloni, L. (2009). Sensitivity and perceptual awareness increase with practice in metacontrast masking. Journal of Vision, 9(10), 18.
Schwiedrzik, C.M., Singer, W., & Melloni, L. (2011). Subjective and objective learning effects dissociate in space and in time. Proceedings of the National Academy of Sciences USA, 108(11), 4506–4511.
Seth, A.K. (2009). Functions of consciousness. In W.P. Banks (Ed.), Encyclopedia of consciousness, Vol. 1 (pp.279–293). Oxford, UK: Academic Press.
Seth, A.K., Dienes, Z., Cleeremans, A., Overgaard, M., & Pessoa, L. (2008). Measuring consciousness: Relating behavioural and neurophysiological approaches. Trends in Cognitive Sciences, 12(8), 314–321.
Summerfield, C., & Egner, T. (2009). Expectation (and attention) in visual cognition. Trends in Cognitive Sciences, 13(9), 403–409.
Zeki, S. (2001). Localization and globalization in conscious vision. Annual Review of Neuroscience, 24, 57–86.