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Block N. What does decoding from the PFC reveal about consciousness? Trends Cogn Sci 2024; 28:804-813. [PMID: 38862352 DOI: 10.1016/j.tics.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 05/12/2024] [Accepted: 05/12/2024] [Indexed: 06/13/2024]
Abstract
Disputes between rival theories of consciousness have often centered on whether perceptual contents can be decoded from the prefrontal cortex (PFC). Failures to decode from the PFC are taken to challenge 'cognitive' theories of consciousness such as the global workspace theory and higher-order monitoring theories, and decoding successes have been taken to confirm these theories. However, PFC decoding shows both too much and too little. Too much because cognitive theories of consciousness do not need PFC rerepresentation of perceptual contents since pointers to perceptual representations suffice. Too little because there is evidence that PFC decoding of perceptual content reflects postperceptual cognitive representation, such as thoughts that have those perceptual contents rather than conscious percepts.
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Affiliation(s)
- Ned Block
- New York University, 5 Washington Place, New York, NY 10003, USA.
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2
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Fleming SM, Shea N. Quality space computations for consciousness. Trends Cogn Sci 2024:S1364-6613(24)00165-7. [PMID: 39025769 DOI: 10.1016/j.tics.2024.06.007] [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: 01/31/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 07/20/2024]
Abstract
The quality space hypothesis about conscious experience proposes that conscious sensory states are experienced in relation to other possible sensory states. For instance, the colour red is experienced as being more like orange, and less like green or blue. Recent empirical findings suggest that subjective similarity space can be explained in terms of similarities in neural activation patterns. Here, we consider how localist, workspace, and higher-order theories of consciousness can accommodate claims about the qualitative character of experience and functionally support a quality space. We review existing empirical evidence for each of these positions, and highlight novel experimental tools, such as altering local activation spaces via brain stimulation or behavioural training, that can distinguish these accounts.
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Affiliation(s)
- Stephen M Fleming
- Wellcome Centre for Human Neuroimaging, University College London, London, UK; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, University College London, London, UK; Department of Experimental Psychology, University College London, London, UK; Canadian Institute for Advanced Research (CIFAR), Brain, Mind, and Consciousness Program, Toronto, ON, Canada.
| | - Nicholas Shea
- Institute of Philosophy, School of Advanced Study, University of London, London, UK; Faculty of Philosophy, University of Oxford, Oxford, UK.
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3
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Panagiotaropoulos TI. An integrative view of the role of prefrontal cortex in consciousness. Neuron 2024; 112:1626-1641. [PMID: 38754374 DOI: 10.1016/j.neuron.2024.04.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/16/2024] [Accepted: 04/24/2024] [Indexed: 05/18/2024]
Abstract
The involvement of the prefrontal cortex (PFC) in consciousness is an ongoing focus of intense investigation. An important question is whether representations of conscious contents and experiences in the PFC are confounded by post-perceptual processes related to cognitive functions. Here, I review recent findings suggesting that neuronal representations of consciously perceived contents-in the absence of post-perceptual processes-can indeed be observed in the PFC. Slower ongoing fluctuations in the electrophysiological state of the PFC seem to control the stability and updates of these prefrontal representations of conscious awareness. In addition to conscious perception, the PFC has been shown to play a critical role in controlling the levels of consciousness as observed during anesthesia, while prefrontal lesions can result in severe loss of perceptual awareness. Together, the convergence of these processes in the PFC suggests its integrative role in consciousness and highlights the complex nature of consciousness itself.
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Dwarakanath A, Kapoor V, Werner J, Safavi S, Fedorov LA, Logothetis NK, Panagiotaropoulos TI. Bistability of prefrontal states gates access to consciousness. Neuron 2023; 111:1666-1683.e4. [PMID: 36921603 DOI: 10.1016/j.neuron.2023.02.027] [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: 06/10/2022] [Revised: 10/24/2022] [Accepted: 02/16/2023] [Indexed: 03/15/2023]
Abstract
Access of sensory information to consciousness has been linked to the ignition of content-specific representations in association cortices. How does ignition interact with intrinsic cortical state fluctuations to give rise to conscious perception? We addressed this question in the prefrontal cortex (PFC) by combining multi-electrode recordings with a binocular rivalry (BR) paradigm inducing spontaneously driven changes in the content of consciousness, inferred from the reflexive optokinetic nystagmus (OKN) pattern. We find that fluctuations between low-frequency (LF, 1-9 Hz) and beta (∼20-40 Hz) local field potentials (LFPs) reflect competition between spontaneous updates and stability of conscious contents, respectively. Both LF and beta events were locally modulated. The phase of the former locked differentially to the competing populations just before a spontaneous transition while the latter synchronized the neuronal ensemble coding the consciously perceived content. These results suggest that prefrontal state fluctuations gate conscious perception by mediating internal states that facilitate perceptual update and stability.
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Affiliation(s)
- Abhilash Dwarakanath
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany; Cognitive Neuroimaging Unit, Institut National de la Santé et de la Recherche Médicale, Commissariat à l'Energie Atomique et aux énergies alternatives, Université Paris-Saclay, NeuroSpin Center, 91191 Gif-sur-Yvette, France.
| | - Vishal Kapoor
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany; International Center for Primate Brain Research, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences, Shanghai, China
| | - Joachim Werner
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany
| | - Shervin Safavi
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany; International Max Planck Research School, Tübingen 72076, Germany
| | - Leonid A Fedorov
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany
| | - Nikos K Logothetis
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany; Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester M13 9PT, UK; International Center for Primate Brain Research, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences, Shanghai, China
| | - Theofanis I Panagiotaropoulos
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen 72076, Germany; Cognitive Neuroimaging Unit, Institut National de la Santé et de la Recherche Médicale, Commissariat à l'Energie Atomique et aux énergies alternatives, Université Paris-Saclay, NeuroSpin Center, 91191 Gif-sur-Yvette, France.
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5
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Hobot J, Skóra Z, Wierzchoń M, Sandberg K. Continuous Theta Burst Stimulation to the left anterior medial prefrontal cortex influences metacognitive efficiency. Neuroimage 2023; 272:119991. [PMID: 36858333 DOI: 10.1016/j.neuroimage.2023.119991] [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: 11/30/2022] [Revised: 02/04/2023] [Accepted: 02/25/2023] [Indexed: 03/03/2023] Open
Abstract
The contribution of the prefrontal areas to visual awareness is critical for the Global Neuronal Workspace Theory and higher-order theories of consciousness. The goal of the present study was to test the potential engagement of the anterior medial prefrontal cortex (aMPFC) in visual awareness judgements. We aimed to temporarily influence the neuronal dynamics of the left aMPFC via neuroplasticity-like mechanisms. We used different Theta Burst Stimulation (TBS) protocols in combination with a visual identification task and visual awareness ratings. Either continuous TBS (cTBS), intermittent TBS (iTBS), or sham TBS was applied prior to the experimental paradigm in a within-participant design. Compared with sham TBS, we observed an increase in participants' ability to judge their perception adequately (metacognitive efficiency) following cTBS but not iTBS. The effect was accompanied by lower visual awareness ratings in incorrect responses. No significant differences in the identification task performance were observed. We interpret these results as evidence of the involvement of PFC in the brain network that underlies metacognition. Further, we discuss whether the results of TMS studies on perceptual metacognition can be taken as evidence for PFC involvement in awareness itself.
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Affiliation(s)
- Justyna Hobot
- Consciousness Lab, Psychology Institute, Jagiellonian University, Krakow, Poland; Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark.
| | - Zuzanna Skóra
- Colourlab, Department of Computer Science, Norwegian University of Science and Technology, Gjøvik, Norway
| | - Michał Wierzchoń
- Consciousness Lab, Psychology Institute, Jagiellonian University, Krakow, Poland
| | - Kristian Sandberg
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark; Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark
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6
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Hatamimajoumerd E, Ratan Murty NA, Pitts M, Cohen MA. Decoding perceptual awareness across the brain with a no-report fMRI masking paradigm. Curr Biol 2022; 32:4139-4149.e4. [PMID: 35981538 DOI: 10.1016/j.cub.2022.07.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/16/2022] [Accepted: 07/26/2022] [Indexed: 12/14/2022]
Abstract
Does perceptual awareness arise within the sensory regions of the brain or within higher-level regions (e.g., the frontal lobe)? To answer this question, researchers traditionally compare neural activity when observers report being aware versus being unaware of a stimulus. However, it is unclear whether the resulting activations are associated with the conscious perception of the stimulus or the post-perceptual processes associated with reporting that stimulus. To address this limitation, we used both report and no-report conditions in a visual masking paradigm while participants were scanned using functional MRI (fMRI). We found that the overall univariate response to visible stimuli in the frontal lobe was robust in the report condition but disappeared in the no-report condition. However, using multivariate patterns, we could still decode in both conditions whether a stimulus reached conscious awareness across the brain, including in the frontal lobe. These results help reconcile key discrepancies in the recent literature and provide a path forward for identifying the neural mechanisms associated with perceptual awareness.
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Affiliation(s)
- Elaheh Hatamimajoumerd
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA; Department of Psychology and Program in Neuroscience, Amherst College, 220 South Pleasant Street, Amherst, MA, USA
| | - N Apurva Ratan Murty
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA; Center for Brains, Minds, and Machines, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
| | - Michael Pitts
- Department of Psychology, Reed College, 3203 Southeast Woodstock Blvd, Portland, OR, USA
| | - Michael A Cohen
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA; Department of Psychology and Program in Neuroscience, Amherst College, 220 South Pleasant Street, Amherst, MA, USA.
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Yang J, Shao Y, Shen YK, Zhu HS, Li B, Yu QY, Kang M, Xu SH, Ying P, Ling Q, Zou J, Wei H, He YL. Altered Intrinsic Brain Activity in Patients With Toothache Using the Percent Amplitude of a Fluctuation Method: A Resting-State fMRI Study. Front Neurol 2022; 13:934501. [PMID: 35812119 PMCID: PMC9259968 DOI: 10.3389/fneur.2022.934501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 05/24/2022] [Indexed: 11/16/2022] Open
Abstract
Objective The percent amplitude of fluctuation (PerAF) technique was utilized to evaluate the neural functions of specific cerebrum areas in patients with toothache (TA). Patients and Methods An aggregation of 18 patients with TA (eight males and 10 females) were included in the study. We also recruited 18 healthy controls (HCs; eight men and 10 women) aligned for sex and age. Resting functional magnetic resonance imaging (rs-fMRI) scans were obtained. Then, we utilized the PerAF method and a support vector machine (SVM) to analyze the image data and measure neural abnormalities in related cerebrum areas. Receiver operating characteristic (ROC) curve analysis was utilized to appraise the two data sets. Results The PerAF signals in the right dorsolateral superior frontal gyrus (RDSFG) and the right posterior central gyrus (RPCG) of TA sufferers were lower than HC signals. These results may reveal neural dysfunctions in relevant cerebrum regions. The AUC values of PerAF in the two areas were 0.979 in the RDSFG and 0.979 in the RPCG. The SVM results suggested that PerAF could be utilized to distinguish the TA group from HCs with a sensitivity of 75.00%, a specificity of 66.67%, and an accuracy of 70.83%. Conclusion Patients with TA had marked differences in PerAF values in some regions of the cerebrum. Changes in PerAF values represented distinctions in blood oxygen level dependent semaphore intensity, which reflected the overactivity or inactivation of some cerebrum areas in those suffering from TA. At the same time, we analyzed the PerAF values of TAs with ROC curve, which can be helpful for the diagnosis of TA severity and subsequent treatment. Our results may help to elucidate the pathological mechanism of TA.
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Affiliation(s)
- Jun Yang
- The Affiliated Stomatological Hospital of Nanchang University, The Key Laboratory of Oral Biomedicine, Nanchang, China
| | - Yi Shao
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yan-Kun Shen
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Hong-Shui Zhu
- The Affiliated Stomatological Hospital of Nanchang University, The Key Laboratory of Oral Biomedicine, Nanchang, China
| | - Bin Li
- Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qiu-Yue Yu
- Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Min Kang
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - San-Hua Xu
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Ping Ying
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qian Ling
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jie Zou
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Hong Wei
- Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yu-Lin He
- Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
- *Correspondence: Yu-Lin He
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8
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Kapoor V, Dwarakanath A, Safavi S, Werner J, Besserve M, Panagiotaropoulos TI, Logothetis NK. Decoding internally generated transitions of conscious contents in the prefrontal cortex without subjective reports. Nat Commun 2022; 13:1535. [PMID: 35318323 PMCID: PMC8940963 DOI: 10.1038/s41467-022-28897-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/17/2022] [Indexed: 11/30/2022] Open
Abstract
A major debate about the neural correlates of conscious perception concerns its cortical organization, namely, whether it includes the prefrontal cortex (PFC), which mediates executive functions, or it is constrained within posterior cortices. It has been suggested that PFC activity during paradigms investigating conscious perception is conflated with post-perceptual processes associated with reporting the contents of consciousness or feedforward signals originating from exogenous stimulus manipulations and relayed via posterior cortical areas. We addressed this debate by simultaneously probing neuronal populations in the rhesus macaque (Macaca mulatta) PFC during a no-report paradigm, capable of instigating internally generated transitions in conscious perception, without changes in visual stimulation. We find that feature-selective prefrontal neurons are modulated concomitantly with subjective perception and perceptual suppression of their preferred stimulus during both externally induced and internally generated changes in conscious perception. Importantly, this enables reliable single-trial, population decoding of conscious contents. Control experiments confirm significant decoding of stimulus contents, even when oculomotor responses, used for inferring perception, are suppressed. These findings suggest that internally generated changes in the contents of conscious visual perception are reliably reflected within the activity of prefrontal populations in the absence of volitional reports or changes in sensory input. The role of the prefrontal cortex in conscious perception is debated because of its involvement in task relevant behaviour, such as subjective perceptual reports. Here, the authors show that prefrontal activity in rhesus macaques correlates with subjective perception and the contents of consciousness can be decoded from prefrontal population activity even without reports.
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Affiliation(s)
- Vishal Kapoor
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany. .,International Center for Primate Brain Research, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Institute of Neuroscience (ION), Chinese Academy of Sciences, Shanghai, China.
| | - Abhilash Dwarakanath
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany
| | - Shervin Safavi
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany.,International Max Planck Research School, Tübingen, 72076, Germany
| | - Joachim Werner
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany
| | - Michel Besserve
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany.,Department of Empirical Inference, Max Planck Institute for Intelligent Systems, 72076, Tübingen, Germany
| | - Theofanis I Panagiotaropoulos
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany. .,Cognitive Neuroimaging Unit, CEA, DSV/I2BM, INSERM, Universite Paris-Sud, Universite Paris-Saclay, Neurospin Center, 91191, Gif/Yvette, France.
| | - Nikos K Logothetis
- Department of Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany.,International Center for Primate Brain Research, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Institute of Neuroscience (ION), Chinese Academy of Sciences, Shanghai, China.,Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, M13 9PT, UK
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9
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Rassi E, Wutz A, Peatfield N, Wiesz N. Efficient Prestimulus Network Integration of Fusiform Face Area Biases Face Perception during Binocular Rivalry. J Cogn Neurosci 2022; 34:1001-1014. [PMID: 35258573 DOI: 10.1162/jocn_a_01843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Ongoing fluctuations in neural excitability and connectivity influence whether or not a stimulus is seen. Do they also influence which stimulus is seen? We recorded magnetoencephalography data while 21 human participants viewed face or house stimuli, either one at a time or under bistable conditions induced through binocular rivalry. Multivariate pattern analysis revealed common neural substrates for rivalrous versus nonrivalrous stimuli with an additional delay of ∼36 msec for the bistable stimulus, and poststimulus signals were source-localized to the fusiform face area. Before stimulus onset followed by a face versus house report, fusiform face area showed stronger connectivity to primary visual cortex and to the rest of the cortex in the alpha frequency range (8-13 Hz), but there were no differences in local oscillatory alpha power. The prestimulus connectivity metrics predicted the accuracy of poststimulus decoding and the delay associated with rivalry disambiguation suggesting that perceptual content is shaped by ongoing neural network states.
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Affiliation(s)
- Elie Rassi
- University of Salzburg.,Radboud University, Nijmegen, The Netherlands
| | - Andreas Wutz
- University of Salzburg.,Massachusetts Institute of Technology
| | | | - Nathan Wiesz
- University of Salzburg.,University of Trento, Rovereto, Italy.,Paracelsus Medical University, Salzburg, Austria
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10
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Bellet J, Gay M, Dwarakanath A, Jarraya B, van Kerkoerle T, Dehaene S, Panagiotaropoulos TI. Decoding rapidly presented visual stimuli from prefrontal ensembles without report nor post-perceptual processing. Neurosci Conscious 2022; 2022:niac005. [PMID: 35223085 PMCID: PMC8868130 DOI: 10.1093/nc/niac005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 12/09/2021] [Accepted: 01/27/2022] [Indexed: 11/14/2022] Open
Abstract
The role of the primate prefrontal cortex (PFC) in conscious perception is debated. The global neuronal workspace theory of consciousness predicts that PFC neurons should contain a detailed code of the current conscious contents. Previous research showed that PFC is indeed activated in paradigms of conscious visual perception, including no-report paradigms where no voluntary behavioral report of the percept is given, thus avoiding a conflation of signals related to visual consciousness with signals related to the report. Still, it has been argued that prefrontal modulation could reflect post-perceptual processes that may be present even in the absence of report, such as thinking about the perceived stimulus, therefore reflecting a consequence rather than a direct correlate of conscious experience. Here, we investigate these issues by recording neuronal ensemble activity from the macaque ventrolateral PFC during briefly presented visual stimuli, either in isolated trials in which stimuli were clearly perceived or in sequences of rapid serial visual presentation (RSVP) in which perception and post-perceptual processing were challenged. We report that the identity of each stimulus could be decoded from PFC population activity even in the RSVP condition. The first visual signals could be detected at 60 ms after stimulus onset and information was maximal at 150 ms. However, in the RSVP condition, 200 ms after the onset of a stimulus, the decoding accuracy quickly dropped to chance level and the next stimulus started to be decodable. Interestingly, decoding in the ventrolateral PFC was stronger compared to posterior parietal cortex for both isolated and RSVP stimuli. These results indicate that neuronal populations in the macaque PFC reliably encode visual stimuli even under conditions that have been shown to challenge conscious perception and/or substantially reduce the probability of post-perceptual processing in humans. We discuss whether the observed activation reflects conscious access, phenomenal consciousness, or merely a preconscious bottom-up wave.
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Affiliation(s)
- Joachim Bellet
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Marion Gay
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Abhilash Dwarakanath
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Bechir Jarraya
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Timo van Kerkoerle
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Stanislas Dehaene
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
| | - Theofanis I Panagiotaropoulos
- Cognitive Neuroimaging Unit, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, INSERM, Université Paris-Saclay, NeuroSpin, Gif-Sur-Yvette 91191, France
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11
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Watanabe T. Causal roles of prefrontal cortex during spontaneous perceptual switching are determined by brain state dynamics. eLife 2021; 10:69079. [PMID: 34713803 PMCID: PMC8631941 DOI: 10.7554/elife.69079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
The prefrontal cortex (PFC) is thought to orchestrate cognitive dynamics. However, in tests of bistable visual perception, no direct evidence supporting such presumable causal roles of the PFC has been reported except for a recent work. Here, using a novel brain-state-dependent neural stimulation system, we identified causal effects on percept dynamics in three PFC activities—right frontal eye fields, dorsolateral PFC (DLPFC), and inferior frontal cortex (IFC). The causality is behaviourally detectable only when we track brain state dynamics and modulate the PFC activity in brain-state-/state-history-dependent manners. The behavioural effects are underpinned by transient neural changes in the brain state dynamics, and such neural effects are quantitatively explainable by structural transformations of the hypothetical energy landscapes. Moreover, these findings indicate distinct functions of the three PFC areas: in particular, the DLPFC enhances the integration of two PFC-active brain states, whereas IFC promotes the functional segregation between them. This work resolves the controversy over the PFC roles in spontaneous perceptual switching and underlines brain state dynamics in fine investigations of brain-behaviour causality. A cube that seems to shift its spatial arrangement as you keep looking; the elegant silhouette of a pirouetting dancer, which starts to spin in the opposite direction the more you stare at it; an illustration that shows two profiles – or is it a vase? These optical illusions are examples of bistable visual perception. Beyond their entertaining aspect, they provide a way for scientists to explore the dynamics of human consciousness, and the neural regions involved in this process. Some studies show that bistable visual perception is associated with the activation of the prefrontal cortex, a brain area involved in complex cognitive processes. However, it is unclear whether this region is required for the illusions to emerge. Some research has showed that even if sections of the prefrontal cortex are temporally deactivated, participants can still experience the illusions. Instead, Takamitsu Watanabe proposes that bistable visual perception is a process tied to dynamic brain states – that is, that distinct regions of the prefontal cortex are required for this fluctuating visual awareness, depending on the state of the whole brain. Such causal link cannot be observed if brain activity is not tracked closely. To investigate this, the brain states of 65 participants were recorded as individuals were experiencing the optical illusions; the activity of their various brain regions could therefore be mapped, and then areas of the prefrontal cortex could precisely be inhibited at the right time using transcranial magnetic stimulation. This revealed that, indeed, prefrontal cortex regions were necessary for bistable visual perception, but not in a simple way. Instead, which ones were required and when depended on activity dynamics taking place in the whole brain. Overall, these results indicate that monitoring brain states is necessary to better understand – and ultimately, control – the neural pathways underlying perception and behaviour.
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Affiliation(s)
- Takamitsu Watanabe
- International Research Centre for Neurointelligence, The University of Tokyo Institutes for Advanced Study, Tokyo, Japan.,RIKEN Centre for Brain Science, Saitama, Japan
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12
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Does the Prefrontal Cortex Play an Essential Role in Consciousness? Insights from Intracranial Electrical Stimulation of the Human Brain. J Neurosci 2021; 41:2076-2087. [PMID: 33692142 DOI: 10.1523/jneurosci.1141-20.2020] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 11/21/2022] Open
Abstract
A central debate in philosophy and neuroscience pertains to whether PFC activity plays an essential role in the neural basis of consciousness. Neuroimaging and electrophysiology studies have revealed that the contents of conscious perceptual experience can be successfully decoded from PFC activity, but these findings might be confounded by postperceptual cognitive processes, such as thinking, reasoning, and decision-making, that are not necessary for consciousness. To clarify the involvement of the PFC in consciousness, we present a synthesis of research that has used intracranial electrical stimulation (iES) for the causal modulation of neural activity in the human PFC. This research provides compelling evidence that iES of only certain prefrontal regions (i.e., orbitofrontal cortex and anterior cingulate cortex) reliably perturbs conscious experience. Conversely, stimulation of anterolateral prefrontal sites, often considered crucial in higher-order and global workspace theories of consciousness, seldom elicits any reportable alterations in consciousness. Furthermore, the wide variety of iES-elicited effects in the PFC (e.g., emotions, thoughts, and olfactory and visual hallucinations) exhibits no clear relation to the immediate environment. Therefore, there is no evidence for the kinds of alterations in ongoing perceptual experience that would be predicted by higher-order or global workspace theories. Nevertheless, effects in the orbitofrontal and anterior cingulate cortices suggest a specific role for these PFC subregions in supporting emotional aspects of conscious experience. Overall, this evidence presents a challenge for higher-order and global workspace theories, which commonly point to the PFC as the basis for conscious perception based on correlative and possibly confounded information.
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Key B, Zalucki O, Brown DJ. Neural Design Principles for Subjective Experience: Implications for Insects. Front Behav Neurosci 2021; 15:658037. [PMID: 34025371 PMCID: PMC8131515 DOI: 10.3389/fnbeh.2021.658037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/07/2021] [Indexed: 02/04/2023] Open
Abstract
How subjective experience is realized in nervous systems remains one of the great challenges in the natural sciences. An answer to this question should resolve debate about which animals are capable of subjective experience. We contend that subjective experience of sensory stimuli is dependent on the brain's awareness of its internal neural processing of these stimuli. This premise is supported by empirical evidence demonstrating that disruption to either processing streams or awareness states perturb subjective experience. Given that the brain must predict the nature of sensory stimuli, we reason that conscious awareness is itself dependent on predictions generated by hierarchically organized forward models of the organism's internal sensory processing. The operation of these forward models requires a specialized neural architecture and hence any nervous system lacking this architecture is unable to subjectively experience sensory stimuli. This approach removes difficulties associated with extrapolations from behavioral and brain homologies typically employed in addressing whether an animal can feel. Using nociception as a model sensation, we show here that the Drosophila brain lacks the required internal neural connectivity to implement the computations required of hierarchical forward models. Consequently, we conclude that Drosophila, and those insects with similar neuroanatomy, do not subjectively experience noxious stimuli and therefore cannot feel pain.
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Affiliation(s)
- Brian Key
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Oressia Zalucki
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Deborah J. Brown
- School of Historical and Philosophical Inquiry, The University of Queensland, Brisbane, QLD, Australia
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Has Silemek AC, Ranjeva J, Audoin B, Heesen C, Gold SM, Kühn S, Weygandt M, Stellmann J. Delayed access to conscious processing in multiple sclerosis: Reduced cortical activation and impaired structural connectivity. Hum Brain Mapp 2021; 42:3379-3395. [PMID: 33826184 PMCID: PMC8249884 DOI: 10.1002/hbm.25440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 01/24/2023] Open
Abstract
Although multiple sclerosis (MS) is frequently accompanied by visuo‐cognitive impairment, especially functional brain mechanisms underlying this impairment are still not well understood. Consequently, we used a functional MRI (fMRI) backward masking task to study visual information processing stratifying unconscious and conscious in MS. Specifically, 30 persons with MS (pwMS) and 34 healthy controls (HC) were shown target stimuli followed by a mask presented 8–150 ms later and had to compare the target to a reference stimulus. Retinal integrity (via optical coherence tomography), optic tract integrity (visual evoked potential; VEP) and whole brain structural connectivity (probabilistic tractography) were assessed as complementary structural brain integrity markers. On a psychophysical level, pwMS reached conscious access later than HC (50 vs. 16 ms, p < .001). The delay increased with disease duration (p < .001, β = .37) and disability (p < .001, β = .24), but did not correlate with conscious information processing speed (Symbol digit modality test, β = .07, p = .817). No association was found for VEP and retinal integrity markers. Moreover, pwMS were characterized by decreased brain activation during unconscious processing compared with HC. No group differences were found during conscious processing. Finally, a complementary structural brain integrity analysis showed that a reduced fractional anisotropy in corpus callosum and an impaired connection between right insula and primary visual areas was related to delayed conscious access in pwMS. Our study revealed slowed conscious access to visual stimulus material in MS and a complex pattern of functional and structural alterations coupled to unconscious processing of/delayed conscious access to visual stimulus material in MS.
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Affiliation(s)
- Arzu C. Has Silemek
- Institut für Neuroimmunologie und Multiple Sklerose (INIMS)Universitätsklinikum Hamburg‐Eppendorf (UKE)HamburgGermany
| | - Jean‐Philippe Ranjeva
- Aix‐Marseille UniversityCNRS, CRMBMMarseille CedexFrance
- APHMHopital de la Timone, CEMEREMMarseilleFrance
| | - Bertrand Audoin
- Aix‐Marseille UniversityCNRS, CRMBMMarseille CedexFrance
- APHMHopital de la Timone, CEMEREMMarseilleFrance
| | - Christoph Heesen
- Institut für Neuroimmunologie und Multiple Sklerose (INIMS)Universitätsklinikum Hamburg‐Eppendorf (UKE)HamburgGermany
- Klinik und Poliklinik für NeurologieUniversitätsklinikum Hamburg‐EppendorfHamburgGermany
| | - Stefan M. Gold
- Institut für Neuroimmunologie und Multiple Sklerose (INIMS)Universitätsklinikum Hamburg‐Eppendorf (UKE)HamburgGermany
- Charité ‐ Universitätsmedizin Berlin, Freie Universität BerlinHumboldt Universität zu Berlin, and Berlin Institute of Health (BIH), Klinik für Psychiatrie & Psychotherapie und Medizinische Klinik m.S. Psychosomatik, Campus Benjamin Franklin (CBF)BerlinGermany
| | - Simone Kühn
- Clinic for Psychiatry and PsychotherapyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
- Lise Meitner Group for Environmental NeuroscienceMax Planck Institute for Human DevelopmentBerlinGermany
| | - Martin Weygandt
- Max Delbrück Center for Molecular Medicine and Charité – Universitätsmedizin Berlin, corporate member of Freie Universität BerlinHumboldt‐Universität zu Berlin, and Berlin Institute of Health, Experimental and Clinical Research CenterBerlinGermany
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität BerlinHumboldt‐Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research CenterBerlinGermany
| | - Jan‐Patrick Stellmann
- Institut für Neuroimmunologie und Multiple Sklerose (INIMS)Universitätsklinikum Hamburg‐Eppendorf (UKE)HamburgGermany
- Aix‐Marseille UniversityCNRS, CRMBMMarseille CedexFrance
- APHMHopital de la Timone, CEMEREMMarseilleFrance
- Klinik und Poliklinik für NeurologieUniversitätsklinikum Hamburg‐EppendorfHamburgGermany
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Hesse JK, Tsao DY. A new no-report paradigm reveals that face cells encode both consciously perceived and suppressed stimuli. eLife 2020; 9:58360. [PMID: 33174836 PMCID: PMC7676863 DOI: 10.7554/elife.58360] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 11/09/2020] [Indexed: 11/17/2022] Open
Abstract
A powerful paradigm to identify neural correlates of consciousness is binocular rivalry, wherein a constant visual stimulus evokes a varying conscious percept. It has recently been suggested that activity modulations observed during rivalry may represent the act of report rather than the conscious percept itself. Here, we performed single-unit recordings from face patches in macaque inferotemporal (IT) cortex using a no-report paradigm in which the animal’s conscious percept was inferred from eye movements. We found that large proportions of IT neurons represented the conscious percept even without active report. Furthermore, on single trials we could decode both the conscious percept and the suppressed stimulus. Together, these findings indicate that (1) IT cortex possesses a true neural correlate of consciousness and (2) this correlate consists of a population code wherein single cells multiplex representation of the conscious percept and veridical physical stimulus, rather than a subset of cells perfectly reflecting consciousness.
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Affiliation(s)
- Janis Karan Hesse
- Division of Biology and Biological Engineering, Computation and Neural Systems, Pasadena, United States.,Howard Hughes Medical Institute, Pasadena, United States
| | - Doris Y Tsao
- Division of Biology and Biological Engineering, Computation and Neural Systems, Pasadena, United States.,Howard Hughes Medical Institute, Pasadena, United States
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