Egocentric Spatial Representation in Action and Perception*

When investigating the neural correlates of consciousness, neuroscientists distinguish between ‘‘conscious state’’ (being awake as opposed to asleep or in a coma), which is regulated by brainstem and thalamic nuclei, and ‘‘conscious representation’’ (awareness of specific phenomenal experience). The advent of functional brain imaging techniques, especially fMRI, enables the noninvasive inquiries of the mechanisms underlying conscious experience, particularly in the visual system. To date, most experimental paradigms designed to study consciousness contrast the response during conscious visual experience with the response during unconscious visual experience (the so-called blindsight phenomenon), or record patterns of brain activation during binocular rivalry, perception of bistable figures, and visual mental imagery. The current data suggest that activity in high-level areas of the ventral visual pathway, but not in V1, are necessary for conscious visual experience. Moreover, visual awareness requires parietal and prefrontal regions (for a recent review, see Rees, Kreiman, & Koch, 2002). The neural correlates of conscious vision, therefore, parallel the distributed cortical networks that modulate visual attention and visual imagery. As most researchers confuse ‘‘awareness’’ with ‘‘consciousness,’’ the reported differential activity during consciousness is currently indistinguishable from that of other higher cognitive functions. In his article, ‘‘Functional fMRI and the Study of Human Consciousness,’’ Dan Lloyd uniquely combines a conceptual analysis of consciousness with neuroscientific methods, in order to characterize the neural manifestations of consciousness (Lloyd, 2002). Lloyd adopts Husserl’s criteria, according to which the phenomenology of consciousness is based on three essential principles: intentionality (the external world as it is experienced and not as it is); superposition (sensory and nonsensory properties are present in perception); and temporality (all objects share perception of present, past, and anticipated future). If indeed these aspects of consciousness are implemented in the brain, the empirical evidence should include temporal flux (with passing time, the multivariate differences between images should increase) and superposition (images sharing task or stimulus conditions should be similar). Lloyd’s methodological approach includes three constraints. First, time points in a scan series are considered individually, because temporality implies that consciousness at each point in time is distinct from the preceding and the proceeding points. Second, subjects are considered individually, because intersubject averaging could eliminate individual expression of consciousness. Finally, brain states are considered globally, seeking distributed patterns of activation that encompass large cortical areas, rather than assuming localized responses. To test his predictions, Lloyd reanalyzes four data sets (Hazeltine, Poldrack, & Gabrieli, 2000; Ishai, Ungerleider, Martin, & Haxby, 2000; Mechelli, Friston, & Price, 2000; Postle, Berger, Taich, & D’Esposito, 2000) provided by The fMRI Data Center. The studies, published in the December 2000 issue of the Journal of Cognitive Neuroscience, included a variety of cognitive tasks (target tracking, passive viewing, delayed matching, reading, and spatial working memory), stimuli (faces, objects, words, pseudowords, 2-D arrays of squares, colored circles), and motor responses (button presses and saccades). Needless to say, none of the original studies was designed for or aimed at underpinning the neural mechanisms of ‘‘neurophenomenology.’’ Nevertheless, Lloyd preprocesses and reanalyzes the raw data to test his predictions about the general structures of consciousness, which by their nature are task and stimulus independent. Using multivariate distance analysis and artificial neural networks, he shows a time–distance effect (i.e., as the time series progressed, the distance between images increased) and that the past and future brain states, retention and protention, respectively, are embedded in present brain states. As time passes, suggests Lloyd, the brain is changing ‘‘globally, incrementally, and monotonically.’’ Previous fMRI studies of consciousness compared one state of awareness with another, assumed localization, and ignored the temporal flux. Lloyd’s original approach proposes methodological and conceptual advantages. Traditionally, fMRI data analysis focused on two parameters, namely the spatial extent of the activation and the amplitude of the response within an activated region. The data are usually displayed as statistical maps indicating the location and size of significant activation, and graphs or histograms showing the percent fMRI signal change. Given the spatial and temporal resolution of the technique, extracting temporal information about the ‘‘tripartite temporality’’ (i.e., the experienced present of National Institutes of Health

Two preliminary comments are necessary. First, throughout this paper I shall use 'see' in an extensional sense which carries an existence entail ment: if you see an F then an F exists in your visual environment. Thus, Macbeth did not see a dagger and you do not see lines of unequal length when looking at a Muller-Lyer diagram. Some philosophers seem to think there is a sense of 'see' which doesn't carry this existence entailment-an intentional sense of 'see' according to which Macbeth did see a dagger, and you do see lines of unequal length when looking at a Muller-Lyer diagram. Obviously on such a reading of 'see' the question of the relation between your visual experience and the thing seen is moot, since no such thing need exist. Nothing in this paper hinges on whether there are or aren't two senses of 'see'. If there are, I'm speaking of seeing in only the one sense. If there aren't, as I'm inclined to believe,1 I'm speaking of seeing in its uni vocal sense. The same remarks hold for 'name' or 'refer', although perhaps with less urgency since there seems to be less tendency to think these verbs have a sense that doesn't entail the existence of what's named or referred to. Also, throughout this paper I shall assume that to see something a person must have a conscious visual experience. It is not entirely obvious

Visual perception, operating below conscious awareness, effortlessly provides the experience of a rich representation of the environment, continuous in space and time. Conscious visual perception is made possible by the 'foveal compromise,' the combination of the high-acuity fovea and a sophisticated suite of eye movements. Our illusory visual experience cannot be understood by introspection, but monitoring eye movements lets us probe the processes of visual perception. Four tasks representing a wide range of complexity were used to explore visual perception; image quality judgments, map reading, model building, and hand-washing. Very short fixation durations were observed in all tasks, some as short as 33 msec. While some tasks showed little variation in eye movement metrics, differences in eye movement patterns and high-level strategies were observed in the model building and hand washing tasks. Performance in the hand washing task revealed a new type of eye movement. 'Planful' eye movements were made to objects well in advance of a subject's interaction with the object. Often occurring in the middle of another task, they provide 'overlapping' temporal information about the environment providing a mechanism to produce our conscious visual experience.

Abstract—The aim of this study is to investigate the difference of EEG dynamics on navigation performance. A tunnel task was designed to classify subjects into allocentric or egocentric spatial representation users. Despite of the differences of mental spatial representation, behavioral performance in general were compatible between the two strategies subjects in the tunnel task. Task-related EEG dynamics in power changes were analyzed using independent component analysis (ICA), time-frequency and non-parametric statistic test. ERSP image results revealed navigation performance-predictive EEG activities which is is expressed in the parietal component by source reconstruction. For egocentric subjects, comparing to trails with well-estimation of homing angle, the power attenuation at the frequencies from 8 to 30 Hz (around alpha and beta band) was stronger when subjects overestimated homing directions, but the attenuated power was decreased when subjects were underestimated the homing angles. However, we did not found performance related brain activities for allocentric subjects, which may due to the functional dis-sociation between the use of allo- and egocentric reference frames.

The author relates his intellectual journey from eye-testing clinician to experimental vision scientist. Starting with the quest for underpinning in physics and physiology of vague clinical propositions and of psychology's acceptance of thresholds as "fuzzy-edged," and a long career pursuing a reductionist agenda in empirical vision science, his journey led to the realization that the full understanding of human vision cannot proceed without factoring in an observer's awareness, with its attendant uncertainty and open-endedness. He finds support in the loss of completeness, finality, and certainty revealed in fundamental twentieth-century formulations of mathematics and physics. Just as biology prospered with the introduction of the emergent, nonreductionist concepts of evolution, vision science has to become comfortable accepting data and receiving guidance from human observers' conscious visual experience.

We present a case report on visual brain plasticity after total blindness acquired in adulthood. SH lost her sight when she was 27. Despite having been totally blind for 43years, she reported to strongly rely on her vivid visual imagery. Three-Tesla magnetic resonance imaging (MRI) of SH and age-matched controls was performed. The MRI sequence included anatomical MRI, resting-state functional MRI, and task-related functional MRI where SH was instructed to imagine colours, faces, and motion. Compared to controls, voxel-based analysis revealed white matter loss along SH's visual pathway as well as grey matter atrophy in the calcarine sulci. Yet we demonstrated activation in visual areas, including V1, using functional MRI. Of the four identified visual resting-state networks, none showed alterations in spatial extent; hence, SH's preserved visual imagery seems to be mediated by intrinsic brain networks of normal extent. Time courses of two of these networks showed increased correlation with that of the inferior posterior default mode network, which may reflect adaptive changes supporting SH's strong internal visual representations. Overall, our findings demonstrate that conscious visual experience is possible even after years of absence of extrinsic input.

Visual-motor contingency during symbol production contributes to short-term changes in the functional connectivity during symbol perception and long-term gains in symbol recognition

It is important to consider the physiological and behavioral mechanisms that allow users to physically interact with virtual environments. Inspired by a neuroanatomical model of perception and action known as the two visual systems hypothesis, we conducted a study with two controlled experiments to compare four different kinds of spatial interaction: (1) voice-based input, (2) pointing with a visual cursor, (3) pointing without a visual cursor, and (4) pointing with a time-lagged visual cursor. Consistent with the two visual systems hypothesis, we found that voice-based input and pointing with a cursor were less robust to a display illusion known as the induced Roelofs effect than pointing without a cursor or even pointing with a lagged cursor. The implications of these findings are discussed, with an emphasis on how the two visual systems model can be used to understand the basis for voice and gestural interactions that support spatial target selection in large screen and immersive environments.

Once you feel it, you see it: Insula and sensory-motor contribution to visual awareness for fearful bodies in parietal neglect

At the beginning of the twentieth century, Gestalt psychologists put forward the concept of psychoneural isomorphism, which was meant to replace Fechner’s obscure notion of psychophysical parallelism and facilitate the search for the neural correlates of the mind. However, the concept has generated much confusion in the debate, and today its role is still unclear. In this contribution, I will attempt a little conceptual spadework in clarifying the concept of psychoneural isomorphism, focusing exclusively on conscious visual perceptual experience and its neural correlates. Firstly, I will outline the history of our concept, and its alleged metaphysical and epistemic roles. Then, I will clarify the nature of isomorphism and rule out its metaphysical role. Finally, I will review some epistemic roles of our concept, zooming in on the work of Jean Petitot, and argue that it does not play a relevant heuristic role. I conclude suggesting that psychoneural isomorphism might play a role in robustness analysis.

Putting Color Back Where It Belongs

The constructive nature of vision is perhaps most evident during hallucinations, mental imagery, synesthesia, perceptual filling-in, and many illusions in which conscious visual experience does not overtly correspond to retinal stimulation: phantom vision. However, the relationship between voluntary and involuntary phantom vision remains largely unknown. Here, we investigated 2 forms of visual phantom color, neon phantom color spreading and voluntary color mental imagery, and their effect on subsequent binocular rivalry perception. Passively viewing neon phantom color induced time sensitive, suppressive effects on subsequent binocular rivalry. These effects could be attenuated by rotating the color inducers, or like color imagery, by concurrent uniform luminance stimulation. The degree of neon color induced rivalry suppression predicted the degree of voluntary color imagery facilitation, both on subsequent rivalry perception. Further, there were functional interactions between voluntary imagery and involuntary neon phantom vision when experienced successively. Our results suggest potential sensory mechanistic commonalities between voluntary and involuntary phantom vision. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Activity-Induced Long-Term Potentiation of Excitatory Synapses in Developing Zebrafish Retina In Vivo

This study investigated whether the lack of visual experience affects the ability to create spatial inferential representations of the survey type. We compared the performance of persons with congenital blindness and that of blindfolded sighted persons on four survey representation-based tasks (Experiment 1). Results showed that persons with blindness performed better than blindfolded sighted controls. We repeated the same tests introducing a third group of persons with late blindness (Experiment 2). This last group performed better than blindfolded sighted participants, whereas differences between participants with late and congenital blindness were nonsignificant. The present findings are compatible with results of other studies, which found that when visual perception is lacking, skill in gathering environmental spatial information provided by nonvisual modalities may contribute to a proper spatial encoding. It is concluded that, although it cannot be asserted that total lack of visual experience incurs no cost, our findings are further evidence that visual experience is not a necessary condition for the development of spatial inferential complex representations.

This paper concerns local yet systematic problems of contrastive underdetermination of model choice in cognitive neuroscience debates about the so-called two visual systems hypothesis. The underdetermination problem is systematically generated by the way certain assumptions about the representationalist nature of computation are translated into experimental practice. The problem is that behavioural data underdetermine the choice between competing representational models. In this paper, I diagnose how these assumptions generate underdetermination problems in the choice between competing functional models of perception–action. Using the tools of philosophy of science, I describe the type of underdetermination and sketch a possible cure.