1
|
Bachmann T. Representational 'touch' and modulatory 'retouch'-two necessary neurobiological processes in thalamocortical interaction for conscious experience. Neurosci Conscious 2021; 2021:niab045. [PMID: 34925911 PMCID: PMC8672242 DOI: 10.1093/nc/niab045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 11/16/2021] [Accepted: 11/30/2021] [Indexed: 12/01/2022] Open
Abstract
Theories of consciousness using neurobiological data or being influenced by these data have been focused either on states of consciousness or contents of consciousness. These theories have occasionally used evidence from psychophysical phenomena where conscious experience is a dependent experimental variable. However, systematic catalog of many such relevant phenomena has not been offered in terms of these theories. In the perceptual retouch theory of thalamocortical interaction, recently developed to become a blend with the dendritic integration theory, consciousness states and contents of consciousness are explained by the same mechanism. This general-purpose mechanism has modulation of the cortical layer-5 pyramidal neurons that represent contents of consciousness as its core. As a surplus, many experimental psychophysical phenomena of conscious perception can be explained by the workings of this mechanism. Historical origins and current views inherent in this theory are presented and reviewed.
Collapse
Affiliation(s)
- Talis Bachmann
- Department of Penal Law, Laboratory of Cognitive Neuroscience, School of Law, University of Tartu (Tallinn Branch), Kaarli puiestee 3, Tallinn 10119, Estonia
| |
Collapse
|
2
|
Lai C, Pellicano GR, Ciacchella C, Guidobaldi L, Altavilla D, Cecchini M, Begotaraj E, Aceto P, Luciani M. Neurophysiological correlates of emotional face perception consciousness. Neuropsychologia 2020; 146:107554. [PMID: 32652090 DOI: 10.1016/j.neuropsychologia.2020.107554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 05/27/2020] [Accepted: 07/03/2020] [Indexed: 01/20/2023]
Abstract
Aim of the present study was to investigate the neurophysiologic correlates of the conscious and not conscious perception of faces (presented for 14, 40, 80 ms) with happy and sad emotional valence. Electroencephalographic data of 22 participants during a report-based visual task were recorded. Both happy and sad faces presented for 14 ms showed a longer N170 latency compared to the faces presented for 40 and 80 ms. A shorter latency of early components (before N170) was found in the right hemisphere and a longer latency in the left one in response to the happy faces presented for 14 ms compared to those presented for longer times. The faces presented for 14 ms, declared as consciously perceived, evoked a higher brain response compared to those declared as not perceived. Parietal and cingulate brain areas showed a lower intensity of the brain response to the consciously perceived faces in the early components. Happy faces showed a greater brain response when consciously detected, while the sad faces induced a greater brain response when not consciously detected. The findings suggest that the N170 may be the epiphenomenon of an earlier consciously detection. Moreover, these preliminary results seem to support a main role of parietal and cingulate brain areas into not conscious perception.
Collapse
Affiliation(s)
- Carlo Lai
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy.
| | - Gaia Romana Pellicano
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Chiara Ciacchella
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Lorenzo Guidobaldi
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Daniela Altavilla
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Marco Cecchini
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Edvaldo Begotaraj
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Paola Aceto
- Department of Anesthesia, Emergency and Intensive Care Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Francesco Vito, 1, 00168, Rome, Italy; Institute of Anesthesiology and Intensive Care Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy
| | - Massimiliano Luciani
- Department of Neuroscience, Catholic University of Sacred Heart, Largo Francesco Vito, 1, 00168, Rome, Italy
| |
Collapse
|
3
|
Bachmann T. Account of consciousness by Christof Koch: Review and questions. Conscious Cogn 2020; 82:102937. [PMID: 32388455 DOI: 10.1016/j.concog.2020.102937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 10/24/2022]
Abstract
This review is set to present the gist of the theoretical account of consciousness recently presented by Christof Koch and pose a couple of questions instigated by this account. The expected answers to these questions would hopefully help to advance our understanding of the basic nature of the conscious mind.
Collapse
Affiliation(s)
- Talis Bachmann
- Department of Penal Law, School of Law, University of Tartu (Tallinn Branch), Kaarli Puiestee 3, 10119 Tallinn, Estonia.
| |
Collapse
|
4
|
Förster J, Koivisto M, Revonsuo A. ERP and MEG correlates of visual consciousness: The second decade. Conscious Cogn 2020; 80:102917. [PMID: 32193077 DOI: 10.1016/j.concog.2020.102917] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/14/2020] [Accepted: 03/07/2020] [Indexed: 01/04/2023]
Abstract
The first decade of event-related potential (ERP) research had established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a posterior negative component in the N2 time range, and the late positivity (LP), an anterior positive component in the P3 time range. Two earlier extensive reviews ten years ago had concluded that VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas LP probably reflects later processes associated with reflective/access consciousness. This article provides an update to those earlier reviews. ERP and MEG studies that have appeared since 2010 and directly compared ERPs between aware and unaware conditions are reviewed, and important new developments in the field are discussed. The result corroborates VAN as the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on LP as an ERP correlate of phenomenal consciousness.
Collapse
Affiliation(s)
- Jona Förster
- Division of Cognitive Neuroscience and Philosophy, University of Skövde, Sweden.
| | - Mika Koivisto
- Department of Psychology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
| | - Antti Revonsuo
- Division of Cognitive Neuroscience and Philosophy, University of Skövde, Sweden; Department of Psychology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
| |
Collapse
|
5
|
Derda M, Koculak M, Windey B, Gociewicz K, Wierzchoń M, Cleeremans A, Binder M. The role of levels of processing in disentangling the ERP signatures of conscious visual processing. Conscious Cogn 2019; 73:102767. [DOI: 10.1016/j.concog.2019.102767] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 06/13/2019] [Accepted: 06/13/2019] [Indexed: 10/26/2022]
|
6
|
Ye M, Lyu Y. Later Positivity Reflects Post-perceptual Processes: Evidence From Immediate Detection and Delayed Detection Tasks. Front Psychol 2019; 10:82. [PMID: 30766499 PMCID: PMC6365435 DOI: 10.3389/fpsyg.2019.00082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/11/2019] [Indexed: 11/24/2022] Open
Abstract
Electrophysiological recordings are usually used to study neural correlates of consciousness (NCCs). The aim of our present study was to use two detection tasks to dissociate the electrophysiological correlates of visual awareness from the post-perceptual processes. In immediate detection task, participants had to quickly report whether the stimulus was presented after stimulus, whereas in delayed detection task, participants had to put off reporting whether the stimulus was presented after stimulus. The results showed that two previously frequently observed electrophysiological NCCs were observed: visual awareness negativity (VAN) and later positivity (LP). Importantly, the amplitude of VAN over posterior temporal and occipital areas was not influenced by the task manipulation. However, the amplitude of LP over parietal, posterior temporal and occipital areas was influenced by the task manipulation during 650–850 ms. These data suggest that VAN is an early electrophysiological correlates of visual awareness, and LP reflects post-perceptual processes required in reporting perceptual awareness.
Collapse
Affiliation(s)
- Muwang Ye
- Academy of Psychology and Behavior, Tianjin Normal University, Tianjin, China
| | - Yong Lyu
- Academy of Psychology and Behavior, Tianjin Normal University, Tianjin, China
| |
Collapse
|
7
|
|
8
|
Juxtaposing the real-time unfolding of subjective experience and ERP neuromarker dynamics. Conscious Cogn 2017; 54:3-19. [DOI: 10.1016/j.concog.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 01/08/2023]
|
9
|
Gallotto S, Sack AT, Schuhmann T, de Graaf TA. Oscillatory Correlates of Visual Consciousness. Front Psychol 2017; 8:1147. [PMID: 28736543 PMCID: PMC5500655 DOI: 10.3389/fpsyg.2017.01147] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/23/2017] [Indexed: 11/21/2022] Open
Abstract
Conscious experiences are linked to activity in our brain: the neural correlates of consciousness (NCC). Empirical research on these NCCs covers a wide range of brain activity signals, measures, and methodologies. In this paper, we focus on spontaneous brain oscillations; rhythmic fluctuations of neuronal (population) activity which can be characterized by a range of parameters, such as frequency, amplitude (power), and phase. We provide an overview of oscillatory measures that appear to correlate with conscious perception. We also discuss how increasingly sophisticated techniques allow us to study the causal role of oscillatory activity in conscious perception (i.e., ‘entrainment’). This review of oscillatory correlates of consciousness suggests that, for example, activity in the alpha-band (7–13 Hz) may index, or even causally support, conscious perception. But such results also showcase an increasingly acknowledged difficulty in NCC research; the challenge of separating neural activity necessary for conscious experience to arise (prerequisites) from neural activity underlying the conscious experience itself (substrates) or its results (consequences).
Collapse
Affiliation(s)
- Stefano Gallotto
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands.,Maastricht Brain Imaging CentreMaastricht, Netherlands
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands.,Maastricht Brain Imaging CentreMaastricht, Netherlands
| | - Teresa Schuhmann
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands.,Maastricht Brain Imaging CentreMaastricht, Netherlands
| | - Tom A de Graaf
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands.,Maastricht Brain Imaging CentreMaastricht, Netherlands
| |
Collapse
|
10
|
Target bottom-up strength determines the extent of attentional modulations on conscious perception. Exp Brain Res 2017; 235:2109-2124. [DOI: 10.1007/s00221-017-4954-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/02/2017] [Indexed: 10/19/2022]
|
11
|
Mazzi C, Mazzeo G, Savazzi S. Markers of TMS-evoked visual conscious experience in a patient with altitudinal hemianopia. Conscious Cogn 2017; 54:143-154. [PMID: 28215463 DOI: 10.1016/j.concog.2017.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/24/2017] [Accepted: 01/24/2017] [Indexed: 11/29/2022]
Abstract
Transcranial magnetic stimulation (TMS) of the occipital and parietal cortices can induce phosphenes, i.e. visual sensations of light without light entering the eyes. In this paper, we adopted a TMS-EEG interactive co-registration approach with a patient (AM) showing altitudinal hemianopia. Occipital and parietal cortices in both hemispheres were stimulated while concurrently recording EEG signal. Results showed that, for all sites, neural activity differentially encoding for the presence vs. absence of a conscious experience could be found in a cluster of electrodes close to the stimulation site at an early (70ms) time-period after TMS. The present data indicate that both occipital and parietal sites are independent early gatekeepers of perceptual awareness, thus, in line with evidence in favor of early correlates of perceptual awareness. Moreover, these data support the valuable contribution of the TMS-EEG approach in patients with visual field defects to investigate the neural processes responsible for perceptual awareness.
Collapse
Affiliation(s)
- Chiara Mazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy
| | - Gaetano Mazzeo
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy
| | - Silvia Savazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy.
| |
Collapse
|
12
|
Aru J, Bachmann T. In and Out of Consciousness: How Does Conscious Processing (D)evolve Over Time? Front Psychol 2017; 8:128. [PMID: 28210236 PMCID: PMC5288355 DOI: 10.3389/fpsyg.2017.00128] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/18/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jaan Aru
- Department of Penal Law, School of Law, University of TartuTartu, Estonia; Chair of Data Science, Institute of Computer Science, University of TartuTartu, Estonia
| | - Talis Bachmann
- Department of Penal Law, School of Law, University of Tartu Tartu, Estonia
| |
Collapse
|
13
|
Rutiku R, Aru J, Bachmann T. General Markers of Conscious Visual Perception and Their Timing. Front Hum Neurosci 2016; 10:23. [PMID: 26869905 PMCID: PMC4740392 DOI: 10.3389/fnhum.2016.00023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/18/2016] [Indexed: 11/13/2022] Open
Abstract
Previous studies have observed different onset times for the neural markers of conscious perception. This variability could be attributed to procedural differences between studies. Here we show that the onset times for the markers of conscious visual perception can strongly vary even within a single study. A heterogeneous stimulus set was presented at threshold contrast. Trials with and without conscious perception were contrasted on 100 balanced subsets of the data. Importantly, the 100 subsets with heterogeneous stimuli did not differ in stimulus content, but only with regard to specific trials used. This approach enabled us to study general markers of conscious visual perception independent of stimulus content, characterize their onset and its variability within one study. N200 and P300 were the two reliable markers of conscious visual perception common to all perceived stimuli and absent for all non-perceived stimuli. The estimated mean onset latency for both markers was shortly after 200 ms. However, the onset latency of these markers was associated with considerable variability depending on which subsets of the data were considered. We show that it is first and foremost the amplitude fluctuation in the condition without conscious perception that explains the observed variability in onset latencies of the markers of conscious visual perception.
Collapse
Affiliation(s)
- Renate Rutiku
- Institute of Psychology, Faculty of Social Sciences and Education, University of TartuTartu, Estonia; Cognitive Psychology Lab, Institute of Public Law, Faculty of Law, University of TartuTallinn, Estonia
| | - Jaan Aru
- Cognitive Psychology Lab, Institute of Public Law, Faculty of Law, University of TartuTallinn, Estonia; Computational Neuroscience Lab, Institute of Computer Science, Faculty of Mathematics and Computer Science, University of TartuTartu, Estonia
| | - Talis Bachmann
- Cognitive Psychology Lab, Institute of Public Law, Faculty of Law, University of Tartu Tallinn, Estonia
| |
Collapse
|
14
|
Morales J, Chiang J, Lau H. Controlling for performance capacity confounds in neuroimaging studies of conscious awareness. Neurosci Conscious 2015; 2015:niv008. [PMID: 29877506 PMCID: PMC5932880 DOI: 10.1093/nc/niv008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 09/13/2015] [Accepted: 09/25/2015] [Indexed: 11/13/2022] Open
Abstract
Studying the neural correlates of conscious awareness depends on a reliable comparison
between activations associated with awareness and unawareness. One particularly difficult
confound to remove is task performance capacity, i.e. the difference in performance
between the conditions of interest. While ideally task performance capacity should be
matched across different conditions, this is difficult to achieve experimentally. However,
differences in performance could theoretically be corrected for mathematically. One such
proposal is found in a recent paper by Lamy, Salti and Bar-Haim [Lamy D, Salti M, Bar-Haim
Y. Neural correlates of subjective awareness and unconscious processing: an ERP study.
J Cognitive Neurosci 2009,21:1435-46], who put forward a
corrective method for an electroencephalography experiment. We argue that their analysis
is essentially grounded in a version of High Threshold Theory, which has been shown to be
inferior in general to Signal Detection Theory. We show through a series of computer
simulations that their correction method only partially removes the influence of
performance capacity, which can yield misleading results. We present a mathematical
correction method based on Signal Detection Theory that is theoretically capable of
removing performance capacity confounds. We discuss the limitations of mathematically
correcting for performance capacity confounds in imaging studies and its impact for
theories about consciousness.
Collapse
Affiliation(s)
- Jorge Morales
- Department of Philosophy, Columbia University, 708 Philosophy Hall Mail Code: 4971 1150 Amsterdam Avenue New York, NY 10027 USA
| | - Jeffrey Chiang
- Department of Psychology, UCLA, 1285 Franz Hall Box 951563 Los Angeles, CA 90095 USA
| | - Hakwan Lau
- Department of Psychology, UCLA, 1285 Franz Hall Box 951563 Los Angeles, CA 90095 USA.,Brain Research Institute, UCLA, 695 Charles E Young Dr. South Los Angeles, CA 90095 USA
| |
Collapse
|
15
|
Rutiku R, Martin M, Bachmann T, Aru J. Does the P300 reflect conscious perception or its consequences? Neuroscience 2015; 298:180-9. [DOI: 10.1016/j.neuroscience.2015.04.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/13/2015] [Accepted: 04/13/2015] [Indexed: 11/25/2022]
|
16
|
Bachmann T. On the brain-imaging markers of neural correlates of consciousness. Front Psychol 2015; 6:868. [PMID: 26161076 PMCID: PMC4479708 DOI: 10.3389/fpsyg.2015.00868] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/12/2015] [Indexed: 11/24/2022] Open
Affiliation(s)
- Talis Bachmann
- Laboratory of Cognitive Neuroscience, Institute of Public Law, University of Tartu Tallinn, Estonia
| |
Collapse
|
17
|
Waves of awareness for occipital and parietal phosphenes perception. Neuropsychologia 2015; 70:114-25. [DOI: 10.1016/j.neuropsychologia.2015.02.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 02/10/2015] [Accepted: 02/16/2015] [Indexed: 10/24/2022]
|
18
|
Pitts MA, Metzler S, Hillyard SA. Isolating neural correlates of conscious perception from neural correlates of reporting one's perception. Front Psychol 2014; 5:1078. [PMID: 25339922 PMCID: PMC4189413 DOI: 10.3389/fpsyg.2014.01078] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 09/08/2014] [Indexed: 11/30/2022] Open
Abstract
To isolate neural correlates of conscious perception (NCCs), a standard approach has been to contrast neural activity elicited by identical stimuli of which subjects are aware vs. unaware. Because conscious experience is private, determining whether a stimulus was consciously perceived requires subjective report: e.g., button-presses indicating detection, visibility ratings, verbal reports, etc. This reporting requirement introduces a methodological confound when attempting to isolate NCCs: The neural processes responsible for accessing and reporting one's percept are difficult to distinguish from those underlying the conscious percept itself. Here, we review recent attempts to circumvent this issue via a modified inattentional blindness paradigm (Pitts et al., 2012) and present new data from a backward masking experiment in which task-relevance and visual awareness were manipulated in a 2 × 2 crossed design. In agreement with our previous inattentional blindness results, stimuli that were consciously perceived yet not immediately accessed for report (aware, task-irrelevant condition) elicited a mid-latency posterior ERP negativity (~200–240 ms), while stimuli that were accessed for report (aware, task-relevant condition) elicited additional components including a robust P3b (~380–480 ms) subsequent to the mid-latency negativity. Overall, these results suggest that some of the NCCs identified in previous studies may be more closely linked with accessing and maintaining perceptual information for reporting purposes than with encoding the conscious percept itself. An open question is whether the remaining NCC candidate (the ERP negativity at 200–240 ms) reflects visual awareness or object-based attention.
Collapse
Affiliation(s)
| | | | - Steven A Hillyard
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| |
Collapse
|
19
|
de Graaf TA, Sack AT. Using brain stimulation to disentangle neural correlates of conscious vision. Front Psychol 2014; 5:1019. [PMID: 25295015 PMCID: PMC4171988 DOI: 10.3389/fpsyg.2014.01019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 08/26/2014] [Indexed: 02/03/2023] Open
Abstract
Research into the neural correlates of consciousness (NCCs) has blossomed, due to the advent of new and increasingly sophisticated brain research tools. Neuroimaging has uncovered a variety of brain processes that relate to conscious perception, obtained in a range of experimental paradigms. But methods such as functional magnetic resonance imaging or electroencephalography do not always afford inference on the functional role these brain processes play in conscious vision. Such empirical NCCs could reflect neural prerequisites, neural consequences, or neural substrates of a conscious experience. Here, we take a closer look at the use of non-invasive brain stimulation (NIBS) techniques in this context. We discuss and review how NIBS methodology can enlighten our understanding of brain mechanisms underlying conscious vision by disentangling the empirical NCCs.
Collapse
Affiliation(s)
- Tom A de Graaf
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands ; Maastricht Brain Imaging Centre Maastricht, Netherlands
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands ; Maastricht Brain Imaging Centre Maastricht, Netherlands
| |
Collapse
|
20
|
Wang M, He BJ. A cross-modal investigation of the neural substrates for ongoing cognition. Front Psychol 2014; 5:945. [PMID: 25206347 PMCID: PMC4143722 DOI: 10.3389/fpsyg.2014.00945] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 08/07/2014] [Indexed: 11/17/2022] Open
Abstract
What neural mechanisms underlie the seamless flow of our waking consciousness? A necessary albeit insufficient condition for such neural mechanisms is that they should be consistently modulated across time were a segment of the conscious stream to be repeated twice. In this study, we experimentally manipulated the content of a story followed by subjects during functional magnetic resonance imaging (fMRI) independently from the modality of sensory input (as visual text or auditory speech) as well as attentional focus. We then extracted brain activity patterns consistently modulated across subjects by the evolving content of the story regardless of whether it was presented visually or auditorily. Specifically, in one experiment we presented the same story to different subjects via either auditory or visual modality. In a second experiment, we presented two different stories simultaneously, one auditorily, one visually, and manipulated the subjects' attentional focus. This experimental design allowed us to dissociate brain activities underlying modality-specific sensory processing from modality-independent story processing. We uncovered a network of brain regions consistently modulated by the evolving content of a story regardless of the sensory modality used for stimulus input, including the superior temporal sulcus/gyrus (STS/STG), the inferior frontal gyrus (IFG), the posterior cingulate cortex (PCC), the medial frontal cortex (MFC), the temporal pole (TP), and the temporoparietal junction (TPJ). Many of these regions have previously been implicated in semantic processing. Interestingly, different stories elicited similar brain activity patterns, but with subtle differences potentially attributable to varying degrees of emotional valence and self-relevance.
Collapse
Affiliation(s)
- Megan Wang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, MD, USA
| | - Biyu J He
- National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, MD, USA
| |
Collapse
|
21
|
Bachmann T, Hudetz AG. It is time to combine the two main traditions in the research on the neural correlates of consciousness: C = L × D. Front Psychol 2014; 5:940. [PMID: 25202297 PMCID: PMC4141455 DOI: 10.3389/fpsyg.2014.00940] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/06/2014] [Indexed: 01/08/2023] Open
Abstract
Research on neural correlates of consciousness has been conducted and carried out mostly from within two relatively autonomous paradigmatic traditions – studying the specific contents of conscious experience and their brain-process correlates and studying the level of consciousness. In the present paper we offer a theoretical integration suggesting that an emphasis has to be put on understanding the mechanisms of consciousness (and not a mere correlates) and in doing this, the two paradigmatic traditions must be combined. We argue that consciousness emerges as a result of interaction of brain mechanisms specialized for representing the specific contents of perception/cognition – the data – and mechanisms specialized for regulating the level of activity of whatever data the content-carrying specific mechanisms happen to represent. Each of these mechanisms are necessary because without the contents there is no conscious experience and without the required level of activity the processed contents remain unconscious. Together the two mechanisms, when activated up to a necessary degree each, provide conditions sufficient for conscious experience to emerge. This proposal is related to pertinent experimental evidence.
Collapse
|
22
|
Pitts MA, Padwal J, Fennelly D, Martínez A, Hillyard SA. Gamma band activity and the P3 reflect post-perceptual processes, not visual awareness. Neuroimage 2014; 101:337-50. [PMID: 25063731 DOI: 10.1016/j.neuroimage.2014.07.024] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/20/2014] [Accepted: 07/13/2014] [Indexed: 11/18/2022] Open
Abstract
A primary goal in cognitive neuroscience is to identify neural correlates of conscious perception (NCC). By contrasting conditions in which subjects are aware versus unaware of identical visual stimuli, a number of candidate NCCs have emerged; among them are induced gamma band activity in the EEG and the P3 event-related potential. In most previous studies, however, the critical stimuli were always directly relevant to the subjects' task, such that aware versus unaware contrasts may well have included differences in post-perceptual processing in addition to differences in conscious perception per se. Here, in a series of EEG experiments, visual awareness and task relevance were manipulated independently. Induced gamma activity and the P3 were absent for task-irrelevant stimuli regardless of whether subjects were aware of such stimuli. For task-relevant stimuli, gamma and the P3 were robust and dissociable, indicating that each reflects distinct post-perceptual processes necessary for carrying-out the task but not for consciously perceiving the stimuli. Overall, this pattern of results challenges a number of previous proposals linking gamma band activity and the P3 to conscious perception.
Collapse
Affiliation(s)
- Michael A Pitts
- Department of Psychology, Reed College, Portland, OR 97202, USA.
| | - Jennifer Padwal
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Daniel Fennelly
- Department of Psychology, Reed College, Portland, OR 97202, USA
| | - Antígona Martínez
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA; Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Steven A Hillyard
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| |
Collapse
|
23
|
Spatiotemporal dissociation of brain activity underlying subjective awareness, objective performance and confidence. J Neurosci 2014; 34:4382-95. [PMID: 24647958 DOI: 10.1523/jneurosci.1820-13.2014] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite intense recent research, the neural correlates of conscious visual perception remain elusive. The most established paradigm for studying brain mechanisms underlying conscious perception is to keep the physical sensory inputs constant and identify brain activities that correlate with the changing content of conscious awareness. However, such a contrast based on conscious content alone would not only reveal brain activities directly contributing to conscious perception, but also include brain activities that precede or follow it. To address this issue, we devised a paradigm whereby we collected, trial-by-trial, measures of objective performance, subjective awareness, and the confidence level of subjective awareness. Using magnetoencephalography recordings in healthy human volunteers, we dissociated brain activities underlying these different cognitive phenomena. Our results provide strong evidence that widely distributed slow cortical potentials (SCPs) correlate with subjective awareness, even after the effects of objective performance and confidence were both removed. The SCP correlate of conscious perception manifests strongly in its waveform, phase, and power. In contrast, objective performance and confidence were both contributed by relatively transient brain activity. These results shed new light on the brain mechanisms of conscious, unconscious, and metacognitive processing.
Collapse
|
24
|
Bachmann T. On the all-or-none rule of conscious perception. Front Hum Neurosci 2013; 7:387. [PMID: 23882209 PMCID: PMC3715692 DOI: 10.3389/fnhum.2013.00387] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/04/2013] [Indexed: 11/15/2022] Open
Affiliation(s)
- Talis Bachmann
- Institute of Public Law and Institute of Psychology, University of Tartu Tartu, Estonia
| |
Collapse
|
25
|
Kirt T, Bachmann T. Perceptual retouch theory derived modeling of interactions in the processing of successive visual objects for consciousness: two-stage synchronization of neuronal oscillators. Conscious Cogn 2012; 22:330-47. [PMID: 22892586 DOI: 10.1016/j.concog.2012.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 07/05/2012] [Accepted: 07/12/2012] [Indexed: 10/28/2022]
Abstract
We introduce a new version of the perceptual retouch model. This model was used for explaining properties of temporal interaction of successive objects in reaching conscious representation. The new model incorporates two interactive binding operations - binding features for objects and binding the bound feature-objects with a large scale oscillatory system that corresponds to perceptual consciousness. Here, the typical result of masking experiments - second object advantage in conscious perception - is achieved by applying the effects of a common synchronizing oscillator with a delay. This delayed modulation of each of the feature-binding first-order oscillators that represent emerging and decaying neural activities of each of the objects guarantees that the oscillating synchrony of the feature-neurons of the following object is higher than the synchrony of the feature-neurons of the first presented object. Thus we model the fact that the following object dominates the preceding object in conscious perception. We also show the capacity of the model to simulate illusory misbinding of features from different objects. The third qualitative effect, the relative release of the first object from backward masking is achieved by priming the non-specific oscillatory modulation ahead in time.
Collapse
Affiliation(s)
- Toomas Kirt
- Laboratory of Cognitive Neuroscience, Institute of Public Law, University of Tartu (Tallinn branch), Kaarli puiestee 3, Tallinn 10119, Estonia
| | | |
Collapse
|
26
|
Missonnier P, Herrmann FR, Zanello A, Bâ MB, Curtis L, Canovas D, Chantraine F, Richiardi J, Giannakopoulos P, Merlo MC. Event-related potentials and changes of brain rhythm oscillations during working memory activation in patients with first-episode psychosis. J Psychiatry Neurosci 2012; 37:95-105. [PMID: 22146152 PMCID: PMC3297068 DOI: 10.1503/jpn.110033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Earlier contributions have documented significant changes in sensory, attention-related endogenous event-related potential (ERP) components and θ band oscillatory responses during working memory activation in patients with schizophrenia. In patients with first-episode psychosis, such studies are still scarce and mostly focused on auditory sensory processing. The present study aimed to explore whether subtle deficits of cortical activation are present in these patients before the decline of working memory performance. METHODS We assessed exogenous and endogenous ERPs and frontal θ event-related synchronization (ERS) in patients with first-episode psychosis and healthy controls who successfully performed an adapted 2-back working memory task, including 2 visual n-backworking memory tasks as well as oddball detection and passive fixation tasks. RESULTS We included 15 patients with first-episode psychosis and 18 controls in this study. Compared with controls, patients with first-episode psychosis displayed increased latencies of early visual ERPs and phasic θ ERS culmination peak in all conditions. However, they also showed a rapid recruitment of working memory-related neural generators, even in pure attention tasks, as indicated by the decreased N200 latency and increased amplitude of sustained θ ERS in detection compared with controls. LIMITATIONS Owing to the limited sample size, no distinction was made between patients with first-episode psychosis with positive and negative symptoms. Although we controlled for the global load of neuroleptics, medication effect cannot be totally ruled out. CONCLUSION The present findings support the concept of a blunted electroencephalographic response in patients with first-episode psychosis who recruit the maximum neural generators in simple attention conditions without being able to modulate their brain activation with increased complexity of working memory tasks.
Collapse
Affiliation(s)
- Pascal Missonnier
- Department of Psychiatry, Geneva University Hospitals and University of Geneva, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Aru J, Bachmann T, Singer W, Melloni L. Distilling the neural correlates of consciousness. Neurosci Biobehav Rev 2011; 36:737-46. [PMID: 22192881 DOI: 10.1016/j.neubiorev.2011.12.003] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 12/07/2011] [Accepted: 12/08/2011] [Indexed: 10/14/2022]
Abstract
Solving the problem of consciousness remains one of the biggest challenges in modern science. One key step towards understanding consciousness is to empirically narrow down neural processes associated with the subjective experience of a particular content. To unravel these neural correlates of consciousness (NCC) a common scientific strategy is to compare perceptual conditions in which consciousness of a particular content is present with those in which it is absent, and to determine differences in measures of brain activity (the so called "contrastive analysis"). However, this comparison appears not to reveal exclusively the NCC, as the NCC proper can be confounded with prerequisites for and consequences of conscious processing of the particular content. This implies that previous results cannot be unequivocally interpreted as reflecting the neural correlates of conscious experience. Here we review evidence supporting this conjecture and suggest experimental strategies to untangle the NCC from the prerequisites and consequences of conscious experience in order to further develop the otherwise valid and valuable contrastive methodology.
Collapse
Affiliation(s)
- Jaan Aru
- Max-Planck Institute for Brain Research, Deutschordnerstrasse 46, Frankfurt am Main, Germany.
| | | | | | | |
Collapse
|
28
|
|