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Zhang Y, Song B, Zhao X, Jin Z, Zhang J, Li L. Meta-analysis of experimental factors influencing single-pulse TMS effects on the early visual cortex. Front Neurosci 2024; 18:1351399. [PMID: 38894939 PMCID: PMC11185874 DOI: 10.3389/fnins.2024.1351399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 05/15/2024] [Indexed: 06/21/2024] Open
Abstract
Background Single-pulse transcranial magnetic stimulation (spTMS) applied to the Early Visual Cortex (EVC) has demonstrated the ability to suppress the perception on visual targets, akin to the effect of visual masking. However, the reported spTMS suppression effects across various studies have displayed inconsistency. Objective We aim to test if the heterogeneity of the spTMS effects can be attributable to variations in experimental factors. Methods We conducted a meta-analysis using data collected from the PubMed and Web of Science databases spanning from 1995 to March 2024. The meta-analysis encompassed a total of 40 independent experiments drawn from 33 original articles. Results The findings unveiled an overall significant spTMS suppression effect on visual perception. Nevertheless, there existed substantial heterogeneity among the experiments. Univariate analysis elucidated that the spTMS effects could be significantly influenced by TMS intensity, visual angle of the stimulus, coil type, and TMS stimulators from different manufacturers. Reliable spTMS suppression effects were observed within the time windows of -80 to 0 ms and 50 to 150 ms. Multivariate linear regression analyses, which included SOA, TMS intensity, visual angle of the stimulus, and coil type, identified SOA as the key factor influencing the spTMS effects. Within the 50 to 150 ms time window, optimal SOAs were identified as 112 ms and 98 ms for objective and subjective performance, respectively. Collectively, multiple experimental factors accounted for 22.9% (r = 0.3353) and 39.9% (r = 0.3724) of the variance in objective and subjective performance, respectively. Comparing univariate and multivariate analyses, it was evident that experimental factors had different impacts on objective performance and subjective performance. Conclusion The present study provided quantitative recommendations for future experiments involving the spTMS effects on visual targets, offering guidance on how to configure experimental factors to achieve the optimal masking effect.
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Affiliation(s)
| | | | | | | | - Junjun Zhang
- MOE Key Lab for Neuroinformation, High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, Center for Psychiatry and Psychology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Ling Li
- MOE Key Lab for Neuroinformation, High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, Center for Psychiatry and Psychology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
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2
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Olkoniemi H, Hurme M, Railo H. Neurologically Healthy Humans' Ability to Make Saccades Toward Unseen Targets. Neuroscience 2023; 513:111-125. [PMID: 36702371 DOI: 10.1016/j.neuroscience.2023.01.014] [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: 07/16/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 01/24/2023]
Abstract
Some patients with a visual field loss due to a lesion in the primary visual cortex (V1) can shift their gaze to stimuli presented in their blind visual field. The extent to which a similar "blindsight" capacity is present in neurologically healthy individuals remains unknown. Using retinotopically navigated transcranial magnetic stimulation (TMS) of V1 (Experiment 1) and metacontrast masking (Experiment 2) to suppress conscious vision, we examined neurologically healthy humans' ability to make saccadic eye movements toward visual targets that they reported not seeing. In the TMS experiment, the participants were more likely to initiate a saccade when a stimulus was presented, and they reported not seeing it, than in trials which no stimulus was presented. However, this happened only in a very small proportion (∼8%) of unseen trials, suggesting that saccadic reactions were largely based on conscious perception. In both experiments, saccade landing location was influenced by unconscious information: When the participants denied seeing the target but made a saccade, the saccade was made toward the correct location (TMS: 68%, metacontrast: 63%) more often than predicted by chance. Signal detection theoretic measures suggested that in the TMS experiment, saccades toward unseen targets may have been based on weak conscious experiences. In both experiments, reduced visibility of the target stimulus was associated with slower and less precise gaze shifts. These results suggest that saccades made by neurologically healthy humans may be influenced by unconscious information, although the initiation of saccades is largely based on conscious vision.
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Affiliation(s)
- Henri Olkoniemi
- Division of Psychology, Faculty of Education and Psychology, University of Oulu, Finland; Department of Psychology and Speech Language Pathology, University of Turku, Finland.
| | - Mikko Hurme
- Department of Psychology and Speech Language Pathology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
| | - Henry Railo
- Department of Psychology and Speech Language Pathology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
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3
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Hurme M, Railo H. Promise and challenges for discovering transcranial magnetic stimulation induced "numbsense"-Commentary on Ro & Koenig (2021). Conscious Cogn 2021; 98:103265. [PMID: 34971969 DOI: 10.1016/j.concog.2021.103265] [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: 09/07/2021] [Revised: 11/18/2021] [Accepted: 12/20/2021] [Indexed: 11/19/2022]
Abstract
The notion that behavioral responses to stimuli can be mediated by separate unconscious and conscious sensory pathways remains popular, but also hotly debated. Recently, Ro and Koenig (2021) reported that when activity in somatosensory cortex was interfered with transcranial magnetic stimulation (TMS), participants could discriminate tactile stimuli they reported not consciously feeling. The study launches an interesting new area of research, helping to uncover mechanisms of unconscious perception that possibly generalize across different sensory modalities. However, we argue here that the study by Ro and Koenig also has several significant shortcomings, and it fails to provide evidence that pathways bypassing primary somatosensory cortex enable unconscious tactile discrimination. By referring to numerous studies investigating TMS-induced blindsight, we outline challenges in demonstrating unconscious sensory pathways using TMS. By facing to these challenges, research investigating TMS-induced numbsense has potential to stimulate progress in stubborn debates and reveal modality-general mechanisms of unconscious perception.
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Affiliation(s)
- Mikko Hurme
- Turku Brain and Mind Center, University of Turku, Turku, Finland.
| | - Henry Railo
- Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Psychology and Speech-Language Pathology, University of Turku, Turku 20014, Finland
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4
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Koivisto M, Leino K, Pekkarinen A, Karttunen J, Railo H, Hurme M. Transcranial magnetic stimulation (TMS)-induced Blindsight of Orientation is Degraded Conscious Vision. Neuroscience 2021; 475:206-219. [PMID: 34480985 DOI: 10.1016/j.neuroscience.2021.08.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 08/16/2021] [Accepted: 08/24/2021] [Indexed: 11/17/2022]
Abstract
Patients with blindsight are blind due to an early visual cortical lesion, but they can discriminate stimuli presented to the blind visual field better than chance. Studies using transcranial magnetic stimulation (TMS) of early visual cortex have tried to induce blindsight-like behaviour in neurologically healthy individuals, but the studies have yielded varied results. We hypothesized that previous demonstrations of TMS-induced blindsight may result from degraded awareness of the stimuli due to the use of dichotomous visibility scales in measuring awareness. In the present study, TMS was applied to early visual cortex during an orientation discrimination task and the subjective scale measuring awareness was manipulated: The participants reported their conscious perception either using a dichotomous scale or a 4-point Perceptual Awareness Scale. Although the results with the dichotomous scale replicated previous reports of blindsight-like behaviour, there was no evidence of TMS-induced blindsight for orientation when the participants used the lowest rating of the 4-point graded scale to indicate that they were not aware of the presence of the stimulus. Moreover, signal detection analyses indicated that across participants, the individual's sensitivity to consciously discriminate orientation predicted behaviour on reportedly unconscious trials. These results suggest that blindsight-like discrimination of orientation in neurologically healthy individuals does not occur for completely invisible stimuli, that is, when the observers do not report any kind of consciousness of the stimulus. TMS-induced blindsight for orientation is likely degraded conscious vision.
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Affiliation(s)
- Mika Koivisto
- Department of Psychology, University of Turku, 20014 Turku, Finland.
| | - Kalle Leino
- Department of Psychology, University of Turku, 20014 Turku, Finland
| | - Aino Pekkarinen
- Department of Psychology, University of Turku, 20014 Turku, Finland
| | - Jaakko Karttunen
- Department of Psychology, University of Turku, 20014 Turku, Finland
| | - Henry Railo
- Department of Psychology, University of Turku, 20014 Turku, Finland
| | - Mikko Hurme
- Department of Psychology, University of Turku, 20014 Turku, Finland
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5
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Is the primary visual cortex necessary for blindsight-like behavior? Review of transcranial magnetic stimulation studies in neurologically healthy individuals. Neurosci Biobehav Rev 2021; 127:353-364. [PMID: 33965459 DOI: 10.1016/j.neubiorev.2021.04.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 12/20/2022]
Abstract
The visual pathways that bypass the primary visual cortex (V1) are often assumed to support visually guided behavior in humans in the absence of conscious vision. This conclusion is largely based on findings on patients: V1 lesions cause blindness but sometimes leave some visually guided behaviors intact-this is known as blindsight. With the aim of examining how well the findings on blindsight patients generalize to neurologically healthy individuals, we review studies which have tried to uncover transcranial magnetic stimulation (TMS) induced blindsight. In general, these studies have failed to demonstrate a completely unconscious blindsight-like capacity in neurologically healthy individuals. A possible exception to this is TMS-induced blindsight of stimulus presence or location. Because blindsight in patients is often associated with some form of introspective access to the visual stimulus, and blindsight may be associated with neural reorganization, we suggest that rather than revealing a dissociation between visually guided behavior and conscious seeing, blindsight may reflect preservation or partial recovery of conscious visual perception after the lesion.
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6
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Janssens SEW, Sack AT, Jessen S, de Graaf TA. Can processing of face trustworthiness bypass early visual cortex? A transcranial magnetic stimulation masking study. Neuropsychologia 2020; 137:107304. [PMID: 31838099 DOI: 10.1016/j.neuropsychologia.2019.107304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 12/02/2019] [Accepted: 12/10/2019] [Indexed: 12/18/2022]
Abstract
As a highly social species, we constantly evaluate human faces to decide whether we can trust someone. Previous studies suggest that face trustworthiness can be processed unconsciously, but the underlying neural pathways remain unclear. Specifically, the question remains whether processing of face trustworthiness relies on early visual cortex (EVC), required for conscious perception. If processing of trustworthiness can bypass EVC, then disrupting EVC should impair subjective (conscious) trustworthiness perception while leaving objective (forced-choice) trustworthiness judgment intact. We applied double-pulse transcranial magnetic stimulation (TMS) to right EVC, at different stimulus onset asynchronies (SOAs) from presentation of a face in either the left or right hemifield. Faces were slightly rotated clockwise or counterclockwise, and were either trustworthy or untrustworthy. On each trial, participants discriminated 1) trustworthiness, 2) stimulus rotation, and 3) reported subjective visibility of trustworthiness. At early SOAs and specifically in the left hemifield, performance on the rotation task was impaired by TMS. Crucially, though TMS also impaired subjective visibility of trustworthiness, no effects on trustworthiness discrimination were obtained. Thus, conscious perception of face trustworthiness (captured by subjective visibility ratings) relies on intact EVC, while objective forced-choice trustworthiness judgments may not. These results are consistent with the hypothesis that objective trustworthiness processing can bypass EVC. For basic visual features, extrastriate pathways are well-established; but face trustworthiness depends on a complex configuration of features. Its potential processing without EVC is therefore of particular interest, further highlighting its ecological relevance.
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Affiliation(s)
- Shanice E W Janssens
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience Maastricht University, Maastricht, the Netherlands; Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, the Netherlands.
| | - Alexander T Sack
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience Maastricht University, Maastricht, the Netherlands; Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, the Netherlands; Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Brain+Nerve Centre, Maastricht University, Maastricht, the Netherlands; Center for Integrative Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Sarah Jessen
- Department of Neurology, University of Lübeck, Lübeck, Germany
| | - Tom A de Graaf
- Section Brain Stimulation and Cognition, Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience Maastricht University, Maastricht, the Netherlands; Maastricht Brain Imaging Centre (MBIC), Maastricht University, Maastricht, the Netherlands; Center for Integrative Neuroscience, Maastricht University, Maastricht, the Netherlands
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7
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Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli. Neuropsychologia 2020; 136:107266. [DOI: 10.1016/j.neuropsychologia.2019.107266] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/22/2022]
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8
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Center EG, Knight R, Fabiani M, Gratton G, Beck DM. Examining the role of feedback in TMS-induced visual suppression: A cautionary tale. Conscious Cogn 2019; 75:102805. [DOI: 10.1016/j.concog.2019.102805] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/04/2019] [Accepted: 08/10/2019] [Indexed: 11/25/2022]
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9
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Fornaciai M, Park J. Spontaneous repulsive adaptation in the absence of attractive serial dependence. J Vis 2019; 19:21. [DOI: 10.1167/19.5.21] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Michele Fornaciai
- Department of Psychological & Brain Sciences, University of Massachusetts, Amherst, MA, USA
| | - Joonkoo Park
- Department of Psychological & Brain Sciences and the Commonwealth Honors College, University of Massachusetts, Amherst, MA, USA
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10
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Ro T. Alpha Oscillations and Feedback Processing in Visual Cortex for Conscious Perception. J Cogn Neurosci 2019; 31:948-960. [PMID: 30912724 DOI: 10.1162/jocn_a_01397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Variability in perception between individuals may be a consequence of different inherent neural processing speeds. To assess whether alpha oscillations systematically reflect a feedback pacing mechanism for cortical processing during visual perception, comparisons were made between alpha oscillations, visual suppression from TMS, visual evoked responses, and metacontrast masking. Peak alpha oscillation frequencies, measured through scalp EEG recordings, significantly correlated with the optimum latencies for visual suppression from TMS of early visual cortex. Individuals with shorter alpha periods (i.e., higher peak alpha frequencies) processed visual information faster than those with longer alpha periods (i.e., lower peak alpha frequencies). Moreover, peak alpha oscillation periods and optimum TMS visual suppression latencies predicted the latencies of late but not early visual evoked responses. Together, these findings demonstrate an important role of alpha oscillatory and late feedback activity in visual cortex for conscious perception. They also show that the timing for visual awareness varies across individuals, depending on the pace of one's endogenous oscillatory cycling frequency.
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Affiliation(s)
- Tony Ro
- The Graduate Center, City University of New York
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11
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Hurme M, Koivisto M, Revonsuo A, Railo H. V1 activity during feedforward and early feedback processing is necessary for both conscious and unconscious motion perception. Neuroimage 2019; 185:313-321. [DOI: 10.1016/j.neuroimage.2018.10.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/25/2018] [Accepted: 10/21/2018] [Indexed: 10/28/2022] Open
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12
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Transcranial magnetic stimulation of early visual cortex suppresses conscious representations in a dichotomous manner without gradually decreasing their precision. Neuroimage 2017; 158:308-318. [DOI: 10.1016/j.neuroimage.2017.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 06/20/2017] [Accepted: 07/09/2017] [Indexed: 11/20/2022] Open
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13
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Leitão J, Thielscher A, Tuennerhoff J, Noppeney U. Comparing TMS perturbations to occipital and parietal cortices in concurrent TMS-fMRI studies-Methodological considerations. PLoS One 2017; 12:e0181438. [PMID: 28767670 PMCID: PMC5540584 DOI: 10.1371/journal.pone.0181438] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/30/2017] [Indexed: 02/07/2023] Open
Abstract
Neglect and hemianopia are two neuropsychological syndromes that are associated with reduced awareness for visual signals in patients’ contralesional hemifield. They offer the unique possibility to dissociate the contributions of retino-geniculate and retino-colliculo circuitries in visual perception. Yet, insights from patient fMRI studies are limited by heterogeneity in lesion location and extent, long-term functional reorganization and behavioural compensation after stroke. Transcranial magnetic stimulation (TMS) has therefore been proposed as a complementary method to investigate the effect of transient perturbations on functional brain organization. This concurrent TMS-fMRI study applied TMS perturbation to occipital and parietal cortices with the aim to ‘mimick’ neglect and hemianopia. Based on the challenges and interpretational limitations of our own study we aim to provide tutorial guidance on how future studies should compare TMS to primary sensory and association areas that are governed by distinct computational principles, neural dynamics and functional architecture.
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Affiliation(s)
- Joana Leitão
- Max Planck Institute for biological Cybernetics, Tübingen, Germany
- Computational Neuroscience and Cognitive Robotics Centre, University of Birmingham, Birmingham, United Kingdom
- Laboratory for Behavioral Neurology and Imaging of Cognition, Department of Neuroscience, University of Geneva, Geneva, Switzerland
- * E-mail:
| | - Axel Thielscher
- Max Planck Institute for biological Cybernetics, Tübingen, Germany
- Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark
- DRCMR, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Johannes Tuennerhoff
- Max Planck Institute for biological Cybernetics, Tübingen, Germany
- University Clinic of Neurology, Tübingen, Germany
| | - Uta Noppeney
- Max Planck Institute for biological Cybernetics, Tübingen, Germany
- Computational Neuroscience and Cognitive Robotics Centre, University of Birmingham, Birmingham, United Kingdom
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14
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Deplancke A, Madelain L, Coello Y. Differential effects of forward and backward masks on the relationship between perception and action. Eur J Neurosci 2016; 43:792-801. [DOI: 10.1111/ejn.13173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 12/05/2015] [Accepted: 01/08/2016] [Indexed: 11/28/2022]
Affiliation(s)
- A. Deplancke
- Univ. Lille; CNRS; CHU Lille; UMR 9193 - SCALab - Sciences Cognitives et Sciences Affectives; F-59000 Lille France
| | - L. Madelain
- Univ. Lille; CNRS; CHU Lille; UMR 9193 - SCALab - Sciences Cognitives et Sciences Affectives; F-59000 Lille France
| | - Y. Coello
- Univ. Lille; CNRS; CHU Lille; UMR 9193 - SCALab - Sciences Cognitives et Sciences Affectives; F-59000 Lille France
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15
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Railo H, Revonsuo A, Koivisto M. Behavioral and electrophysiological evidence for fast emergence of visual consciousness. Neurosci Conscious 2015; 2015:niv004. [PMID: 30774982 PMCID: PMC6368270 DOI: 10.1093/nc/niv004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 05/26/2015] [Accepted: 06/11/2015] [Indexed: 11/14/2022] Open
Abstract
A fundamental unsettled dispute concerns how fast the brain generates subjective visual experiences. Both early visual cortical activation and later activity in fronto-parietal global neuronal workspace correlate with conscious vision, but resolving which of the correlates causally triggers conscious vision has proved a methodological impasse. We show that participants can report whether or not they consciously perceived a stimulus in just over 200 ms. These fast consciousness reports were extremely reliable, and did not include reflexive, unconscious responses. The neural events that causally generate conscious vision must have occurred before these behavioral reports. Analyses on single-trial neural correlates of consciousness revealed that the late cortical processing in fronto-parietal global neuronal workspace (∼300 ms) started after the fastest consciousness reports, ruling out the possibility that this late activity directly reflects the emergence of visual consciousness. The consciousness reports were preceded by a negative amplitude difference (∼160-220 ms) that spread from occipital to frontal cortex, suggesting that this correlate underlies the emergence of conscious vision.
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Affiliation(s)
- Henry Railo
- Department of Psychology, University of Turku, 20014, Finland
- Centre for Cognitive Neuroscience, University of Turku, 20014, Finland
- Brain and Mind Centre, University of Turku, 20014, Finland
| | - Antti Revonsuo
- Department of Psychology, University of Turku, 20014, Finland
- Centre for Cognitive Neuroscience, University of Turku, 20014, Finland
- Brain and Mind Centre, University of Turku, 20014, Finland
- School of Bioscience, University of Skövde, SE-54128, Sweden
| | - Mika Koivisto
- Department of Psychology, University of Turku, 20014, Finland
- Centre for Cognitive Neuroscience, University of Turku, 20014, Finland
- Brain and Mind Centre, University of Turku, 20014, Finland
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16
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Key B. Fish do not feel pain and its implications for understanding phenomenal consciousness. BIOLOGY & PHILOSOPHY 2014; 30:149-165. [PMID: 25798021 PMCID: PMC4356734 DOI: 10.1007/s10539-014-9469-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 12/06/2014] [Indexed: 05/28/2023]
Abstract
Phenomenal consciousness or the subjective experience of feeling sensory stimuli is fundamental to human existence. Because of the ubiquity of their subjective experiences, humans seem to readily accept the anthropomorphic extension of these mental states to other animals. Humans will typically extrapolate feelings of pain to animals if they respond physiologically and behaviourally to noxious stimuli. The alternative view that fish instead respond to noxious stimuli reflexly and with a limited behavioural repertoire is defended within the context of our current understanding of the neuroanatomy and neurophysiology of mental states. Consequently, a set of fundamental properties of neural tissue necessary for feeling pain or experiencing affective states in vertebrates is proposed. While mammals and birds possess the prerequisite neural architecture for phenomenal consciousness, it is concluded that fish lack these essential characteristics and hence do not feel pain.
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Affiliation(s)
- Brian Key
- School of Biomedical Sciences, University of Queensland, Brisbane, 4072 Australia
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17
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Tapia E, Beck DM. Probing feedforward and feedback contributions to awareness with visual masking and transcranial magnetic stimulation. Front Psychol 2014; 5:1173. [PMID: 25374548 PMCID: PMC4204434 DOI: 10.3389/fpsyg.2014.01173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/26/2014] [Indexed: 11/13/2022] Open
Abstract
A number of influential theories posit that visual awareness relies not only on the initial, stimulus-driven (i.e., feedforward) sweep of activation but also on recurrent feedback activity within and between brain regions. These theories of awareness draw heavily on data from masking paradigms in which visibility of one stimulus is reduced due to the presence of another stimulus. More recently transcranial magnetic stimulation (TMS) has been used to study the temporal dynamics of visual awareness. TMS over occipital cortex affects performance on visual tasks at distinct time points and in a manner that is comparable to visual masking. We draw parallels between these two methods and examine evidence for the neural mechanisms by which visual masking and TMS suppress stimulus visibility. Specifically, both methods have been proposed to affect feedforward as well as feedback signals when applied at distinct time windows relative to stimulus onset and as a result modify visual awareness. Most recent empirical evidence, moreover, suggests that while visual masking and TMS impact stimulus visibility comparably, the processes these methods affect may not be as similar as previously thought. In addition to reviewing both masking and TMS studies that examine feedforward and feedback processes in vision, we raise questions to guide future studies and further probe the necessary conditions for visual awareness.
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Affiliation(s)
- Evelina Tapia
- Beckman Institute, University of Illinois Urbana-Champaign Urbana, IL USA
| | - Diane M Beck
- Beckman Institute, University of Illinois Urbana-Champaign Urbana, IL USA ; Department of Psychology, University of Illinois Urbana-Champaign Urbana, IL, USA
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18
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de Graaf TA, Koivisto M, Jacobs C, Sack AT. The chronometry of visual perception: review of occipital TMS masking studies. Neurosci Biobehav Rev 2014; 45:295-304. [PMID: 25010557 DOI: 10.1016/j.neubiorev.2014.06.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/26/2014] [Accepted: 06/27/2014] [Indexed: 11/17/2022]
Abstract
Transcranial magnetic stimulation (TMS) continues to deliver on its promise as a research tool. In this review article we focus on the application of TMS to early visual cortex (V1, V2, V3) in studies of visual perception and visual awareness. Depending on the asynchrony between visual stimulus onset and TMS pulse (SOA), TMS can suppress visual perception, allowing one to track the time course of functional relevance (chronometry) of early visual cortex for vision. This procedure has revealed multiple masking effects ('dips'), some consistently (∼+100ms SOA) but others less so (∼-50ms, ∼-20ms, ∼+30ms, ∼+200ms SOA). We review the state of TMS masking research, focusing on the evidence for these multiple dips, the relevance of several experimental parameters to the obtained 'masking curve', and the use of multiple measures of visual processing (subjective measures of awareness, objective discrimination tasks, priming effects). Lastly, we consider possible future directions for this field. We conclude that while TMS masking has yielded many fundamental insights into the chronometry of visual perception already, much remains unknown. Not only are there several temporal windows when TMS pulses can induce visual suppression, even the well-established 'classical' masking effect (∼+100ms) may reflect more than one functional visual process.
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Affiliation(s)
- Tom A de Graaf
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200MD Maastricht, The Netherlands; Maastricht Brain Imaging Center, PO Box 616, 6200MD Maastricht, The Netherlands.
| | - Mika Koivisto
- Centre for Cognitive Neuroscience and Department of Psychology, University of Turku, FIN-20014 Turku, Finland
| | - Christianne Jacobs
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200MD Maastricht, The Netherlands; Maastricht Brain Imaging Center, PO Box 616, 6200MD Maastricht, The Netherlands; Department of Psychology, Faculty of Science and Technology, University of Westminster, 309 Regent Street, W1B 2HW London, United Kingdom
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200MD Maastricht, The Netherlands; Maastricht Brain Imaging Center, PO Box 616, 6200MD Maastricht, The Netherlands
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Railo H, Andersson E, Kaasinen V, Laine T, Koivisto M. Unlike in Clinical Blindsight Patients, Unconscious Processing of Chromatic Information Depends on Early Visual Cortex in Healthy Humans. Brain Stimul 2014; 7:415-20. [DOI: 10.1016/j.brs.2014.01.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 11/27/2022] Open
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20
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Tapia E, Mazzi C, Savazzi S, Beck DM. Phosphene-guided transcranial magnetic stimulation of occipital but not parietal cortex suppresses stimulus visibility. Exp Brain Res 2014; 232:1989-97. [PMID: 24584900 DOI: 10.1007/s00221-014-3888-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
Abstract
Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0-130 ms after the onset of the stimulus in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window.
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Affiliation(s)
- Evelina Tapia
- Department of Psychology, Beckman Institute, University of Illinois, 405 N. Mathews Ave., Urbana, IL, 61801, USA,
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Do conscious perception and unconscious processing rely on independent mechanisms? A meta-contrast study. Conscious Cogn 2014; 24:22-32. [PMID: 24398259 DOI: 10.1016/j.concog.2013.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 12/10/2013] [Accepted: 12/13/2013] [Indexed: 11/23/2022]
Abstract
There is currently no consensus regarding what measures are most valid to demonstrate perceptual processing without awareness. Likewise, whether conscious perception and unconscious processing rely on independent mechanisms or lie on a continuum remains a matter of debate. Here, we addressed these issues by comparing the time courses of subjective reports, objective discrimination performance and response priming during meta-contrast masking, under similar attentional demands. We found these to be strikingly similar, suggesting that conscious perception and unconscious processing cannot be dissociated by their time course. Our results also demonstrate that unconscious processing, indexed by response priming, occurs, and that objective discrimination performance indexes the same conscious processes as subjective visibility reports. Finally, our results underscore the role of attention by showing that how much attention the stimulus receives relative to the mask, rather than whether processing is measured by conscious discrimination or by priming, determines the time course of meta-contrast masking.
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Overlapping activity periods in early visual cortex and posterior intraparietal area in conscious visual shape perception: A TMS study. Neuroimage 2014; 84:765-74. [DOI: 10.1016/j.neuroimage.2013.09.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/15/2013] [Accepted: 09/20/2013] [Indexed: 11/23/2022] Open
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Koivisto M, Henriksson L, Revonsuo A, Railo H. Unconscious response priming by shape depends on geniculostriate visual projection. Eur J Neurosci 2012; 35:623-33. [DOI: 10.1111/j.1460-9568.2011.07973.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Railo H, Tallus J, Hämäläinen H. Right visual field advantage for perceived contrast: Correlation with an auditory bias and handedness. Brain Cogn 2011; 77:391-400. [DOI: 10.1016/j.bandc.2011.08.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 08/17/2011] [Accepted: 08/29/2011] [Indexed: 11/27/2022]
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25
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Tracking the processes behind conscious perception: A review of event-related potential correlates of visual consciousness. Conscious Cogn 2011; 20:972-83. [DOI: 10.1016/j.concog.2011.03.019] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 03/01/2011] [Accepted: 03/18/2011] [Indexed: 11/21/2022]
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