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McEwan J, Kritikos A, Zeljko M. Involvement of the superior colliculi in crossmodal correspondences. Atten Percept Psychophys 2024; 86:931-941. [PMID: 38418807 PMCID: PMC11062976 DOI: 10.3758/s13414-024-02866-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2024] [Indexed: 03/02/2024]
Abstract
There is an increasing body of evidence suggesting that there are low-level perceptual processes involved in crossmodal correspondences. In this study, we investigate the involvement of the superior colliculi in three basic crossmodal correspondences: elevation/pitch, lightness/pitch, and size/pitch. Using a psychophysical design, we modulate visual input to the superior colliculus to test whether the superior colliculus is required for behavioural crossmodal congruency effects to manifest in an unspeeded multisensory discrimination task. In the elevation/pitch task, superior colliculus involvement is required for a behavioural elevation/pitch congruency effect to manifest in the task. In the lightness/pitch and size/pitch task, we observed a behavioural elevation/pitch congruency effect regardless of superior colliculus involvement. These results suggest that the elevation/pitch correspondence may be processed differently to other low-level crossmodal correspondences. The implications of a distributed model of crossmodal correspondence processing in the brain are discussed.
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Affiliation(s)
- John McEwan
- School of Psychology, The University of Queensland, St. Lucia, Queensland, 4072, Australia.
| | - Ada Kritikos
- School of Psychology, The University of Queensland, St. Lucia, Queensland, 4072, Australia
| | - Mick Zeljko
- School of Psychology, The University of Queensland, St. Lucia, Queensland, 4072, Australia
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2
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Schmid D, Hesse C, Schenk T. The redundant target paradigm and its use as a blindsight-test: A meta-analytic study. Cortex 2023; 169:326-352. [PMID: 37981442 DOI: 10.1016/j.cortex.2023.08.015] [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: 04/26/2023] [Revised: 08/04/2023] [Accepted: 08/30/2023] [Indexed: 11/21/2023]
Abstract
The redundant target effect (RTE) is the well-known effect whereby a single target is detected faster when a second, redundant target is presented simultaneously. The RTE was shown in different experimental designs and applied in various clinical contexts. However, there are also studies showing non-effects or effects in the opposite direction. Our meta-analysis aims to investigate the replicability of the RTE. Herein, we focused on the clinical context within which the RTE has been applied most often and for which it gained particular prominence: The research on blindsight and other forms of residual vision in patients with damage to the neuronal visual system. The application of the RTE in clinical contexts assumes that whenever vision is present, an RTE will be found. Put differently, the RTE as a tool to uncover residual vision presumes that the RTE is a consistent feature of vision in the healthy population. We found a significant summary effect size of the RTE in healthy participants. The effect size depended on certain experimental features: task type, target configuration in the redundant condition, and how reaction times were computed in the single condition. A specific feature combination is typically used in blindsight research. Analyzing studies with this feature combination revealed a significant summary effect size in healthy participants predicting positive RTEs for future studies. A power-analysis revealed a required sample size of 14 participants to obtain an RTE with high reliability. However, the required sample size is rarely reached in blindsight research. Rather, blindsight research is mostly based on single-case studies. In summary, the RTE is a robust effect on group level but does not occur in every single individual. This means failure to obtain an RTE in a single patient should not be interpreted as evidence for the absence of residual vision in this patient.
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Affiliation(s)
- Doris Schmid
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany.
| | - Constanze Hesse
- School of Psychology, University of Aberdeen, King's College, Aberdeen, United Kingdom.
| | - Thomas Schenk
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany.
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3
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Abstract
The superior colliculus (SC) is a subcortical brain structure that is relevant for sensation, cognition, and action. In nonhuman primates, a rich history of studies has provided unprecedented detail about this structure's role in controlling orienting behaviors; as a result, the primate SC has become primarily regarded as a motor control structure. However, as in other species, the primate SC is also a highly visual structure: A fraction of its inputs is retinal and complemented by inputs from visual cortical areas, including the primary visual cortex. Motivated by this, recent investigations are revealing the rich visual pattern analysis capabilities of the primate SC, placing this structure in an ideal position to guide orienting movements. The anatomical proximity of the primate SC to both early visual inputs and final motor control apparatuses, as well as its ascending feedback projections to the cortex, affirms an important role for this structure in active perception.
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Affiliation(s)
- Ziad M Hafed
- Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany;
- Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | | | - Chih-Yang Chen
- Institute for the Advanced Study of Human Biology, Kyoto University, Kyoto, Japan;
| | - Amarender R Bogadhi
- Central Nervous System Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany;
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4
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Kehoe DH, Schießer L, Malik H, Fallah M. Motion distractors perturb saccade programming later in time than static distractors. CURRENT RESEARCH IN NEUROBIOLOGY 2023; 4:100092. [PMID: 37397809 PMCID: PMC10313862 DOI: 10.1016/j.crneur.2023.100092] [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: 09/25/2022] [Revised: 05/24/2023] [Accepted: 05/27/2023] [Indexed: 07/04/2023] Open
Abstract
The mechanism that reweights oculomotor vectors based on visual features is unclear. However, the latency of oculomotor visual activations gives insight into their antecedent featural processing. We compared the oculomotor processing time course of grayscale, task-irrelevant static and motion distractors during target selection by continuously measuring a battery of human saccadic behavioral metrics as a function of time after distractor onset. The motion direction was towards or away from the target and the motion speed was fast or slow. We compared static and motion distractors and observed that both distractors elicited curved saccades and shifted endpoints at short latencies (∼25 ms). After 50 ms, saccade trajectory biasing elicited by motion distractors lagged static distractor trajectory biasing by 10 ms. There were no such latency differences between distractor motion directions or motion speeds. This pattern suggests that additional processing of motion stimuli occurred prior to the propagation of visual information into the oculomotor system. We examined the interaction of distractor processing time (DPT) with two additional factors: saccadic reaction time (SRT) and saccadic amplitude. Shorter SRTs were associated with shorter DPT latencies of biased saccade trajectories. Both SRT and saccadic amplitude were associated with the magnitude of saccade trajectory biases.
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Affiliation(s)
- Devin H. Kehoe
- Department of Psychology, York University, Toronto, M3J 1P3, Canada
- Centre for Vision Research, York University, Toronto, M3J 1P3, Canada
- VISTA: Vision Science to Applications, York University, Toronto, M3J 1P3, Canada
- Canadian Action and Perception Network, Canada
| | - Lukas Schießer
- Institute of Cognitive Science, Universität Osnabrück, Osnabrück, 49074, Germany
| | - Hassaan Malik
- School of Kinesiology and Health Science, York University, Toronto, M3J 1P3, Canada
| | - Mazyar Fallah
- Department of Psychology, York University, Toronto, M3J 1P3, Canada
- Centre for Vision Research, York University, Toronto, M3J 1P3, Canada
- VISTA: Vision Science to Applications, York University, Toronto, M3J 1P3, Canada
- Canadian Action and Perception Network, Canada
- School of Kinesiology and Health Science, York University, Toronto, M3J 1P3, Canada
- College of Biological Science, University of Guelph, Guelph, N1G 2W1, Canada
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5
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Adámek P, Langová V, Horáček J. Early-stage visual perception impairment in schizophrenia, bottom-up and back again. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2022; 8:27. [PMID: 35314712 PMCID: PMC8938488 DOI: 10.1038/s41537-022-00237-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 02/17/2022] [Indexed: 01/01/2023]
Abstract
Visual perception is one of the basic tools for exploring the world. However, in schizophrenia, this modality is disrupted. So far, there has been no clear answer as to whether the disruption occurs primarily within the brain or in the precortical areas of visual perception (the retina, visual pathways, and lateral geniculate nucleus [LGN]). A web-based comprehensive search of peer-reviewed journals was conducted based on various keyword combinations including schizophrenia, saliency, visual cognition, visual pathways, retina, and LGN. Articles were chosen with respect to topic relevance. Searched databases included Google Scholar, PubMed, and Web of Science. This review describes the precortical circuit and the key changes in biochemistry and pathophysiology that affect the creation and characteristics of the retinal signal as well as its subsequent modulation and processing in other parts of this circuit. Changes in the characteristics of the signal and the misinterpretation of visual stimuli associated with them may, as a result, contribute to the development of schizophrenic disease.
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Affiliation(s)
- Petr Adámek
- Third Faculty of Medicine, Charles University, Prague, Czech Republic. .,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic.
| | - Veronika Langová
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
| | - Jiří Horáček
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
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6
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Blue-light effects on saccadic eye movements and attentional disengagement. Atten Percept Psychophys 2021; 83:1713-1728. [PMID: 33751450 DOI: 10.3758/s13414-021-02250-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2021] [Indexed: 12/19/2022]
Abstract
People are constantly exposed to high-energy blue light as they spend considerable amounts of time reading and browsing materials on electronic products like computers and cellphones. Recent studies suggest that the stimulation of intrinsically photosensitive retinal ganglion cells (ipRGCs)-a newly discovered type of photoreceptor shown to be particularly sensitive to blue light-activates brain regions related to eye movements and attentional orienting (e.g., frontal eye fields). It remains unclear, however, whether and how blue light affects eye movements and attention behaviorally. We examined this by adopting the gap paradigm in which participants made saccades to a peripheral target as quickly and accurately as possible while the fixation sign vanished (i.e., the gap condition) or remained visible. Participants were exposed to blue and orange light on two separate days. Faster saccade latency under blue light was found across two experiments, and the results indicate that blue light shortened saccade latency when attention and eye movements operate simultaneously. Our findings provide evidence for the blue-light facilitatory effect on eye movements and attentional disengagement, and suggest that blue light can enhance the speed of saccadic eye movements.
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7
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Asymmetrical Pseudo-Extinction Phenomenon in the Illusory Line Motion. Symmetry (Basel) 2020. [DOI: 10.3390/sym12081322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Illusory Line Motion (i.e., a static line, presented after a lateral cue, is perceived as movement in the opposite direction to the cue) has been used to study a phenomenon of perceptual asymmetry. We have demonstrated the presence of an illusion of leftward movement, even in the presence of bilateral symmetrical cues. We have classified this phenomenon as one of pseudo-extinction. The paradigm of the four experiments performed was always the same: a white line, briefly presented alone or preceded by one or two lateral cues (150 ms), was judged by a group of young participants to be moving either to one side or the other. The asymmetrical effect in the bilateral cue condition was observed with horizontal lines (Experiment 1 and 4), and not with vertical or oblique (Experiment 2 and 3). These results suggest that the effect is linked to the asymmetry of the horizontal spatial planum and the mechanisms of spatial attention. Experiment 4 verified whether the Illusory Line Motion involves the collicular pathway by using blue stimuli for the cues, which activate less the Superior Colliculus (SC), with negative results. We interpreted the asymmetrical pseudo-extinction phenomenon in terms of a right-space exogenous attention advantage.
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Kveraga K, Im HY, Ward N, Adams RB. Fast saccadic and manual responses to faces presented to the koniocellular visual pathway. J Vis 2020; 20:9. [PMID: 32097485 PMCID: PMC7343428 DOI: 10.1167/jov.20.2.9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The parallel pathways of the human visual system differ in their tuning to luminance, color, and spatial frequency. These attunements recently have been shown to propagate to differential processing of higher-order stimuli, facial threat cues, in the magnocellular (M) and parvocellular (P) pathways, with greater sensitivity to clear and ambiguous threat, respectively. The role of the third, koniocellular (K) pathway in facial threat processing, however, remains unknown. To address this gap in knowledge, we briefly presented peripheral face stimuli psychophysically biased towards M, P, or K pathways. Observers were instructed to report via a key-press whether the face was angry or neutral while their eye movements and manual responses were recorded. We found that short-latency saccades were made more frequently to faces presented in the K channel than to P or M channels. Saccade latencies were not significantly modulated by expressive and identity cues. In contrast, manual response latencies and accuracy were modulated by both pathway biasing and by interactions of facial expression with facial masculinity, such that angry male faces elicited the fastest, and angry female faces, the least accurate, responses. We conclude that face stimuli can evoke fast saccadic and manual responses when projected to the K pathway.
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9
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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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10
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Koller K, Rafal RD. Saccade latency bias toward temporal hemifield: Evidence for role of retinotectal tract in mediating reflexive saccades. Neuropsychologia 2019; 128:276-281. [DOI: 10.1016/j.neuropsychologia.2018.01.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 01/16/2018] [Accepted: 01/18/2018] [Indexed: 11/28/2022]
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11
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Abstract
The nature of the relationship between spatial attention and eye movements has been the subject of intense debate for more than 40 years. Two ideas have dominated this debate. First is the idea that spatial attention shares common neural mechanisms with eye movement programming, characterizing attention as an eye movement that has been prepared but not executed. Second, based on the observation that attention shifts to saccade targets, several theories have proposed that saccade programming necessarily recruits attentional resources. In this chapter, we review the evidence for each of these ideas and discuss some of the limitations and challenges in confirming their predictions. Although they are clearly dependent under some circumstances, dissociations between spatial attention and eye movements, and clear differences in their basic functions, point to the existence of two interconnected, but separate, systems.
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12
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Michalczyk Ł, Paszulewicz J, Bielas J, Wolski P. Is saccade preparation required for inhibition of return (IOR)? Neurosci Lett 2018; 665:13-17. [DOI: 10.1016/j.neulet.2017.11.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/01/2017] [Accepted: 11/14/2017] [Indexed: 10/18/2022]
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13
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Color-Change Detection Activity in the Primate Superior Colliculus. eNeuro 2017; 4:eN-NWR-0046-17. [PMID: 28413825 PMCID: PMC5388837 DOI: 10.1523/eneuro.0046-17.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/24/2017] [Accepted: 03/25/2017] [Indexed: 11/25/2022] Open
Abstract
The primate superior colliculus (SC) is a midbrain structure that participates in the control of spatial attention. Previous studies examining the role of the SC in attention have mostly used luminance-based visual features (e.g., motion, contrast) as the stimuli and saccadic eye movements as the behavioral response, both of which are known to modulate the activity of SC neurons. To explore the limits of the SC’s involvement in the control of spatial attention, we recorded SC neuronal activity during a task using color, a visual feature dimension not traditionally associated with the SC, and required monkeys to detect threshold-level changes in the saturation of a cued stimulus by releasing a joystick during maintained fixation. Using this color-based spatial attention task, we found substantial cue-related modulation in all categories of visually responsive neurons in the intermediate layers of the SC. Notably, near-threshold changes in color saturation, both increases and decreases, evoked phasic bursts of activity with magnitudes as large as those evoked by stimulus onset. This change-detection activity had two distinctive features: activity for hits was larger than for misses, and the timing of change-detection activity accounted for 67% of joystick release latency, even though it preceded the release by at least 200 ms. We conclude that during attention tasks, SC activity denotes the behavioral relevance of the stimulus regardless of feature dimension and that phasic event-related SC activity is suitable to guide the selection of manual responses as well as saccadic eye movements.
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14
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Veale R, Hafed ZM, Yoshida M. How is visual salience computed in the brain? Insights from behaviour, neurobiology and modelling. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160113. [PMID: 28044023 PMCID: PMC5206280 DOI: 10.1098/rstb.2016.0113] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2016] [Indexed: 01/07/2023] Open
Abstract
Inherent in visual scene analysis is a bottleneck associated with the need to sequentially sample locations with foveating eye movements. The concept of a 'saliency map' topographically encoding stimulus conspicuity over the visual scene has proven to be an efficient predictor of eye movements. Our work reviews insights into the neurobiological implementation of visual salience computation. We start by summarizing the role that different visual brain areas play in salience computation, whether at the level of feature analysis for bottom-up salience or at the level of goal-directed priority maps for output behaviour. We then delve into how a subcortical structure, the superior colliculus (SC), participates in salience computation. The SC represents a visual saliency map via a centre-surround inhibition mechanism in the superficial layers, which feeds into priority selection mechanisms in the deeper layers, thereby affecting saccadic and microsaccadic eye movements. Lateral interactions in the local SC circuit are particularly important for controlling active populations of neurons. This, in turn, might help explain long-range effects, such as those of peripheral cues on tiny microsaccades. Finally, we show how a combination of in vitro neurophysiology and large-scale computational modelling is able to clarify how salience computation is implemented in the local circuit of the SC.This article is part of the themed issue 'Auditory and visual scene analysis'.
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Affiliation(s)
- Richard Veale
- Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan
| | - Ziad M Hafed
- Physiology of Active Vision Laboratory, Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Masatoshi Yoshida
- Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan
- School of Life Science, The Graduate University for Advanced Studies, Hayama, Japan
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15
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Ajina S, Bridge H. Blindsight and Unconscious Vision: What They Teach Us about the Human Visual System. Neuroscientist 2016; 23:529-541. [PMID: 27777337 DOI: 10.1177/1073858416673817] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Damage to the primary visual cortex removes the major input from the eyes to the brain, causing significant visual loss as patients are unable to perceive the side of the world contralateral to the damage. Some patients, however, retain the ability to detect visual information within this blind region; this is known as blindsight. By studying the visual pathways that underlie this residual vision in patients, we can uncover additional aspects of the human visual system that likely contribute to normal visual function but cannot be revealed under physiological conditions. In this review, we discuss the residual abilities and neural activity that have been described in blindsight and the implications of these findings for understanding the intact system.
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Affiliation(s)
- Sara Ajina
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Holly Bridge
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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16
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Abstract
AbstractMore than 35 years ago, Meltzoff and Moore (1977) published their famous article, “Imitation of facial and manual gestures by human neonates.” Their central conclusion, that neonates can imitate, was and continues to be controversial. Here, we focus on an often-neglected aspect of this debate, namely, neonatal spontaneous behaviors themselves. We present a case study of a paradigmatic orofacial “gesture,” namely tongue protrusion and retraction (TP/R). Against the background of new research on mammalian aerodigestive development, we ask: How does the human aerodigestive system develop, and what role does TP/R play in the neonate's emerging system of aerodigestion? We show that mammalian aerodigestion develops in two phases: (1) from the onset of isolated orofacial movementsin uteroto the postnatal mastery of suckling at 4 months after birth; and (2) thereafter, from preparation to the mastery of mastication and deglutition of solid foods. Like other orofacial stereotypies, TP/R emerges in the first phase and vanishes prior to the second. Based upon recent advances in activity-driven early neural development, we suggest a sequence of three developmental events in which TP/R might participate: the acquisition of tongue control, the integration of the central pattern generator (CPG) for TP/R with other aerodigestive CPGs, and the formation of connections within the cortical maps of S1 and M1. If correct, orofacial stereotypies are crucial to the maturation of aerodigestion in the neonatal period but also unlikely to co-occur with imitative behavior.
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17
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Monkey neurophysiology to clinical neuroscience and back again. Proc Natl Acad Sci U S A 2016; 113:6591-3. [PMID: 27226305 DOI: 10.1073/pnas.1606344113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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18
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Chang DHF, Hess RF, Mullen KT. Color responses and their adaptation in human superior colliculus and lateral geniculate nucleus. Neuroimage 2016; 138:211-220. [PMID: 27150230 DOI: 10.1016/j.neuroimage.2016.04.067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 04/26/2016] [Indexed: 10/21/2022] Open
Abstract
We use an fMRI adaptation paradigm to explore the selectivity of human responses in the lateral geniculate nucleus (LGN) and superior colliculus (SC) to red-green color and achromatic contrast. We measured responses to red-green (RG) and achromatic (ACH) high contrast sinewave counter-phasing rings with and without adaptation, within a block design. The signal for the RG test stimulus was reduced following both RG and ACH adaptation, whereas the signal for the ACH test was unaffected by either adaptor. These results provide compelling evidence that the human LGN and SC have significant capacity for color adaptation. Since in the LGN red-green responses are mediated by P cells, these findings are in contrast to earlier neurophysiological data from non-human primates that have shown weak or no contrast adaptation in the P pathway. Cross-adaptation of the red-green color response by achromatic contrast suggests unselective response adaptation and points to a dual role for P cells in responding to both color and achromatic contrast. We further show that subcortical adaptation is not restricted to the geniculostriate system, but is also present in the superior colliculus (SC), an oculomotor region that until recently, has been thought to be color-blind. Our data show that the human SC not only responds to red-green color contrast, but like the LGN, shows reliable but unselective adaptation.
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Affiliation(s)
- Dorita H F Chang
- McGill Vision Research, Department of Ophthalmology, McGill University, Canada
| | - Robert F Hess
- McGill Vision Research, Department of Ophthalmology, McGill University, Canada
| | - Kathy T Mullen
- McGill Vision Research, Department of Ophthalmology, McGill University, Canada.
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19
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Express saccades and superior colliculus responses are sensitive to short-wavelength cone contrast. Proc Natl Acad Sci U S A 2016; 113:6743-8. [PMID: 27140613 DOI: 10.1073/pnas.1600095113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A key structure for directing saccadic eye movements is the superior colliculus (SC). The visual pathways that project to the SC have been reported to carry only luminance information and not color information. Short-wavelength-sensitive cones (S-cones) in the retina make little or no contribution to luminance signals, leading to the conclusion that S-cone stimuli should be invisible to SC neurons. The premise that S-cone stimuli are invisible to the SC has been used in numerous clinical and human psychophysical studies. The assumption that the SC cannot use S-cone stimuli to guide behavior has never been tested. We show here that express saccades, which depend on the SC, can be driven by S-cone input. Further, express saccade reaction times and changes in SC activity depend on the amount of S-cone contrast. These results demonstrate that the SC can use S-cone stimuli to guide behavior. We conclude that the use of S-cone stimuli is insufficient to isolate SC function in psychophysical and clinical studies of human subjects.
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20
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Abstract
Following a salient cue that attracts attention to a specific spatial location, perceptual processing of information at that location is facilitated if the interval between the cue and target is brief, or, is inhibited if the interval between the cue and target is long. The mechanisms mediating these attentional dynamics continue to be the subject on ongoing debate. On one classic account, facilitation and inhibition of return (IOR) are two ends of a continuum, generated by the same underlying mechanism. Other accounts have postulated that these two attentional processes emerge from independent systems. To address these alternatives, we report data from three experiments in which a cue and its ensuing target are presented to the same or different eyes at varying cue-target intervals. Whereas the onset of facilitation was apparent earlier when the cue and target shared the eye-of-origin, the onset of IOR was not affected by the eye to which the cue and target were presented. This finding implicates at least some, if not full, independence in the system(s) that give rise to attentional facilitation and IOR, and, moreover, suggests that facilitation may be more reliant on subcortical levels of the visual pathways than IOR.
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21
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Acting without seeing: eye movements reveal visual processing without awareness. Trends Neurosci 2015; 38:247-58. [PMID: 25765322 DOI: 10.1016/j.tins.2015.02.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/03/2015] [Accepted: 02/09/2015] [Indexed: 11/23/2022]
Abstract
Visual perception and eye movements are considered to be tightly linked. Diverse fields, ranging from developmental psychology to computer science, utilize eye tracking to measure visual perception. However, this prevailing view has been challenged by recent behavioral studies. Here, we review converging evidence revealing dissociations between the contents of perceptual awareness and different types of eye movement. Such dissociations reveal situations in which eye movements are sensitive to particular visual features that fail to modulate perceptual reports. We also discuss neurophysiological, neuroimaging, and clinical studies supporting the role of subcortical pathways for visual processing without awareness. Our review links awareness to perceptual-eye movement dissociations and furthers our understanding of the brain pathways underlying vision and movement with and without awareness.
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Mizzi R, Michael GA. The role of the collicular pathway in the salience-based progression of visual attention. Behav Brain Res 2014; 270:330-8. [DOI: 10.1016/j.bbr.2014.05.043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 05/16/2014] [Accepted: 05/20/2014] [Indexed: 11/25/2022]
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