Decoding eye-of-origin outside of awareness

In the primary visual cortex of many mammals, ocular dominance columns segregate information from the two eyes. Yet under controlled conditions, most human observers are unable to correctly report the eye to which a stimulus has been shown, indicating that this information is lost during subsequent processing. This study investigates whether eye-of-origin information is available in the pattern of electrophysiological activity evoked by visual stimuli, recorded using EEG and decoded using multivariate pattern analysis. Observers (N=24) viewed sine-wave grating and plaid stimuli of different orientations, shown to either the left or right eye (or both). Using a support vector machine, eye-of-origin could be decoded above chance at around 140 and 220ms post stimulus onset, yet observers were at chance for reporting this information. Other stimulus features, such as binocularity, orientation, spatial pattern, and the presence of interocular conflict (i.e. rivalry), could also be decoded using the same techniques, though all of these were perceptually discriminable above chance. A control analysis found no evidence to support the possibility that eye dominance was responsible for the eye-of-origin effects. These results support a structural explanation for multivariate decoding of electrophysiological signals – information organised in cortical columns can be decoded, even when observers are unaware of this information

I, NEURON: the neuron as the collective

Purpose – In the last half-century, individual sensory neurons have been bestowed with characteristics of the whole human being, such as behavior and its oft-presumed precursor, consciousness. This anthropomorphization is pervasive in the literature. It is also absurd, given what we know about neurons, and it needs to be abolished. This study aims to first understand how it happened, and hence why it persists. Design/methodology/approach – The peer-reviewed sensory-neurophysiology literature extends to hundreds (perhaps thousands) of papers. Here, more than 90 mainstream papers were scrutinized. Findings – Anthropomorphization arose because single neurons were cast as “observers” who “identify”, “categorize”, “recognize”, “distinguish” or “discriminate” the stimuli, using math-based algorithms that reduce (“decode”) the stimulus-evoked spike trains to the particular stimuli inferred to elicit them. Without “decoding”, there is supposedly no perception. However, “decoding” is both unnecessary and unconfirmed. The neuronal “observer” in fact consists of the laboratory staff and the greater society that supports them. In anthropomorphization, the neuron becomes the collective. Research limitations/implications – Anthropomorphization underlies the widespread application to neurons Information Theory and Signal Detection Theory, making both approaches incorrect. Practical implications – A great deal of time, money and effort has been wasted on anthropomorphic Reductionist approaches to understanding perception and consciousness. Those resources should be diverted into more-fruitful approaches. Originality/value – A long-overdue scrutiny of sensory-neuroscience literature reveals that anthropomorphization, a form of Reductionism that involves the presumption of single-neuron consciousness, has run amok in neuroscience. Consciousness is more likely to be an emergent property of the brain

Knowing with Which Eye We See: Utrocular Discrimination and Eye-Specific Signals in Human Visual Cortex

Neurophysiological and behavioral reports converge to suggest that monocular neurons in the primary visual cortex are biased toward low spatial frequencies, while binocular neurons favor high spatial frequencies. Here we tested this hypothesis with functional magnetic resonance imaging (fMRI). Human participants viewed flickering gratings at one of two spatial frequencies presented to either the left or the right eye, and judged which of the two eyes was being stimulated (utrocular discrimination). Using multivoxel pattern analysis we found that local spatial patterns of signals in primary visual cortex (V1) allowed successful decoding of the eye-of-origin. Decoding was above chance for low but not high spatial frequencies, confirming the presence of a bias reported by animal studies in human visual cortex. Behaviorally, we found that reliable judgment of the eye-of-origin did not depend on spatial frequency. We further analyzed the mean response in visual cortex to our stimuli and revealed a weak difference between left and right eye stimulation. Our results are thus consistent with the interpretation that participants use overall levels of neural activity in visual cortex, perhaps arising due to local luminance differences, to judge the eye-of-origin. Taken together, we show that it is possible to decode eye-specific voxel pattern information in visual cortex but, at least in healthy participants with normal binocular vision, these patterns are unrelated to awareness of which eye is being stimulated

Laminar fMRI: applications for cognitive neuroscience

The cortex is a massively recurrent network, characterized by feedforward and feedback connections between brain areas as well as lateral connections within an area. Feedforward, horizontal and feedback responses largely activate separate layers of a cortical unit, meaning they can be dissociated by lamina-resolved neurophysiological techniques. Such techniques are invasive and are therefore rarely used in humans. However, recent developments in high spatial resolution fMRI allow for non-invasive, in vivo measurements of brain responses specific to separate cortical layers. This provides an important opportunity to dissociate between feedforward and feedback brain responses, and investigate communication between brain areas at a more fine- grained level than previously possible in the human species. In this review, we highlight recent studies that successfully used laminar fMRI to isolate layer-specific feedback responses in human sensory cortex. In addition, we review several areas of cognitive neuroscience that stand to benefit from this new technological development, highlighting contemporary hypotheses that yield testable predictions for laminar fMRI. We hope to encourage researchers with the opportunity to embrace this development in fMRI research, as we expect that many future advancements in our current understanding of human brain function will be gained from measuring lamina-specific brain responses

Tracing the Biological Roots of Knowledge

The essay is a critical review of three possible approaches in the theory of knowledge while tracing the biological roots of knowledge: empiricist, rationalist and developmentalist approaches. Piaget's genetic epistemology, a developmentalist approach, is one of the first comprehensive treatments on the question of tracing biological roots of knowledge. This developmental approach is currently opposed, without questioning the biological roots of knowledge, by the more popular rationalist approach, championed by Chomsky. Developmental approaches are generally coherent with cybernetic models, of which the theory of autopoiesis proposed by Maturana and Varela made a significant theoretical move in proposing an intimate connection between metabolism and knowledge. Modular architecture is currently considered more or less an undisputable model for both biology as well as cognitive science. By suggesting that modulation of modules is possible by motor coordination, a proposal is made to account for higher forms of conscious cognition within the four distinguishable layers of the human mind. Towards the end, the problem of life and cognition is discussed in the context of the evolution of complex cognitive systems, suggesting the unique access of phylogeny during the ontogeny of human beings as a very special case, and how the problem cannot be dealt with independent of the evolution of coding systems in nature

Primary visual cortex as a saliency map: parameter-free prediction of behavior from V1 physiology

It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. We report this hypothesis' first quantitative prediction, derived without free parameters, and its confirmation by human behavioral data. The hypothesis provides a direct link between V1 neural responses to a visual location and the saliency of that location to guide attention exogenously. In a visual input containing many bars, one of them saliently different from all the other bars which are identical to each other, saliency at the singleton's location can be measured by the shortness of the reaction time in a visual search task to find the singleton. The hypothesis predicts quantitatively the whole distribution of the reaction times to find a singleton unique in color, orientation, and motion direction from the reaction times to find other types of singletons. The predicted distribution matches the experimentally observed distribution in all six human observers. A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs. Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functional roles like visual decoding or endogenous attention.Comment: 11 figures, 66 page

Multisensory mechanisms of body ownership and self-location

Having an accurate sense of the spatial boundaries of the body is a prerequisite for interacting with the environment and is thus essential for the survival of any organism with a central nervous system. Every second, our brain receives a staggering amount of information from the body across different sensory channels, each of which features a certain degree of noise. Despite the complexity of the incoming multisensory signals, the brain manages to construct and maintain a stable representation of our own body and its spatial relationships to the external environment. This natural “in-body” experience is such a fundamental subjective feeling that most of us take it for granted. However, patients with lesions in particular brain areas can experience profound disturbances in their normal sense of ownership over their body (somatoparaphrenia) or lose the feeling of being located inside their physical body (out-of-body experiences), suggesting that our “in-body” experience depends on intact neural circuitry in the temporal, frontal, and parietal brain regions. The question at the heart of this thesis relates to how the brain combines visual, tactile, and proprioceptive signals to build an internal representation of the bodily self in space. Over the past two decades, perceptual body illusions have become an important tool for studying the mechanisms underlying our sense of body ownership and self-location. The most influential of these illusions is the rubber hand illusion, in which ownership of an artificial limb is induced via the synchronous stroking of a rubber hand and an individual’s hidden real hand. Studies of this illusion have shown that multisensory integration within the peripersonal space is a key mechanism for bodily self-attribution. In Study I, we showed that the default sense of ownership of one’s real hand, not just the sense of rubber hand ownership, also depends on spatial and temporal multisensory congruence principles implemented in fronto-parietal brain regions. In Studies II and III, we characterized two novel perceptual illusions that provide strong support for the notion that multisensory integration within the peripersonal space is intimately related to the sense of limb ownership, and we examine the role of vision in this process. In Study IV, we investigated a fullbody version of the rubber hand illusion—the “out-of-body illusion”—and show that it can be used to induce predictable changes in one’s sense of self-location and body ownership. Finally, in Study V, we used the out-of-body illusion to “perceptually teleport” participants during brain imaging and identify activity patterns specific to the sense of self-location in a given position in space. Together, these findings shed light on the role of multisensory integration in building the experience of the bodily self in space and provide initial evidence for how representations of body ownership and self-location interact in the brain

Polysemy in Advertising

The article reviews the conceptual foundations of advertising polysemy – the occurrence of different interpretations for the same advertising message. We discuss how disciplines as diverse as psychology, semiotics and literary theory have dealt with the issue of polysemy, and provide translations and integration among these multiple perspectives. From such review we draw recurrent themes to foster future research in the area and to show how seemingly opposed methodological and theoretical perspectives complement and extend each other. Implications for advertising research and practice are discussed.Advertising;Polysemy;Semiotics

Critical looking in advertising : Gerry Human's University of Johannesburg Alumni Exhibition : Humanism: The Art of Selling

In 2008 Gerry Human, the chief creative officer of Ogilvy South Africa, was invited to exhibit pieces from his creative career as an alumnus of the University of Johannesburg (the former TWR) at the FADA Gallery. The ironic title of the exhibition, Humanism: The Art of Selling, suggested that Human was aware of the potential ironies and incongruities involved in exhibiting pieces of advertising within the context of a university art gallery. As a more or less reflexive practitioner, Human provoked in the framing of the exhibition questions about the power of advertis­ing in a post-modern world where the field of legitimate culture, the aesthetic, and the university as institutional categories may have lost their potential to affect major social change. I examine the implications of this statement asking what methodological and theoretical approaches are most effective in examining complex, ironic and multilayered advertising products within a gallery context. In particular, I use the exhibition as a vehicle to ask how advertising may be pedagogically framed, to produce critical, media literate students in the field of visual culture (Willis 1999; Giroux 2005). In doing so, I explore the tensions that exist between understanding the consumption of advertisements and popular culture as passive, hegemonic and constructivist notions of creative consump­tion, problematising easy readings of advertising products in terms of WJT Mitchell's (2005) notion that images exert power over readers in complex ways, Pierre Bourdieu's (1993) understanding of the cultural field as one where social distinction is produced, and Jean Baudrillard's (1995) ideas around the proliferation of commodities and their value in an economy of signs.A variety ofvisual methodologies (Rose 2006) are critically examined in terms of developing the "interpretative repertoires" of students in relation to the complexity of Human's print advertisements. Human's framing of the exhibition is examined in terms of critical discourse analysis and audience studies. A social semiotic/critical discourse method is proposed as a method for allowing students to unpack the structure of addressability of particular advertisements produced by Human. Here, I draw on Gunther Kress and Theo Van Leeuwen's (2006) social semiotic methods, as put forward in Reading Images: The Grammar of Visual Design -methods such as the "transactional gaze", "narrative and conceptual structure", "social distance and framing" -in order to argue for the predominant use of the declarative as Humans' primary mode of visual and textual address. I link this visual strategy to Bourdieu's (1993) theories of how class distinction is constructed through visuality and begin to unravel the complexities involved in dealing with advertisements in terms of class and the desiring gaze exploring the tensions that may exist between students' lived experiences, the textually mediated world of consumer culture (Fairclough 2006) and the interpretative repertoires students are exposed to in a formal learning environment