Among psychologists and vision scientists,binocular rivalry has enjoyed sustainedinterest for decades dating back to the 19thcentury. In recent years, however, rivalry''saudience has expanded to includeneuroscientists who envision rivalry as a tool for exploring the neural concomitants ofconscious visual awareness and perceptualorganization. For rivalry''s potential to berealized, workers using this tool need toknow details of this fascinating phenomenon,and providing those details is the purpose ofthis article. After placing rivalry in ahistorical context, I summarize major findingsconcerning the spatial characteristics and thetemporal dynamics (...) of rivalry, discuss two majortheoretical accounts of rivalry ( eye vs stimulus rivalry) and speculate on possibleneural concomitants of binocular rivalry. (shrink)

I propose that primary conscious awareness arises from synchronized activity in dendrites of neurons in dorsal thalamic nuclei, mediated particularly by inhibitory interactions with thalamic reticular neurons. In support, I offer four evidential pillars: consciousness is restricted to the results of cortical computations; thalamus is the common locus of action of brain injury in vegetative state and of general anesthetics; the anatomy and physiology of the thalamus imply a central role in consciousness; neural synchronization is a neural correlate of consciousness.

In attempts to formulate a computational understanding of brain function, one of the fundamental concerns is the data structure by which the brain represents information. For many decades, a conceptual framework has dominated the thinking of both brain modelers and neurobiologists. That framework is referred to here as "classical neural networks." It is well supported by experimental data, although it may be incomplete. A characterization of this framework will be offered in the next section. Difficulties in modeling important functional aspects (...) of the brain on the basis of classical neural networks alone have led to the recognition that another, general mechanism must be invoked to explain brain function. That mechanism I call " binding." Binding by neural signal synchrony had been mentioned several times in the liter ature before it was fully formulated as a general phenomenon. Although experimental evidence for neural syn chrony was soon found, the idea was largely ignored for many years. Only recently has it become a topic of animated discussion. In what follows, I will summarize the nature and the roots of the idea of binding, especially of temporal binding, and will discuss some of the objec tions raised against it. (shrink)

Binocular rivalry provides a useful situation for studying the relation between the temporal flow of conscious experience and the temporal dynamics of neural activity. After proposing a phenomenological framework for understanding temporal aspects of consciousness, we review experimental research on multistable perception and binocular rivalry, singling out various methodological, theoretical, and empirical aspects of this research relevant to studying the flow of experience. We then review an experimental study from our group explicitly concerned with relating the temporal dynamics of rivalrous (...) experience to the temporal dynamics of cortical activity. Drawing attention to the importance of dealing with ongoing activity and its inherent changing nature at both phenomenological and neurodynamical levels, we argue that the notions of recurrence and variability are pertinent to understanding rivalry in particular and the flow of experience in general. (shrink)

Neural Darwinism (ND) is a large scale selectionist theory of brain development and function that has been hypothesized to relate to consciousness. According to ND, consciousness is entailed by reentrant interactions among neuronal populations in the thalamocortical system (the ‘dynamic core’). These interactions, which permit high-order discriminations among possible core states, confer selective advantages on organisms possessing them by linking current perceptual events to a past history of value-dependent learning. Here, we assess the consistency of ND with 16 widely recognized (...) properties of consciousness, both physiological (for example, consciousness is associated with widespread, relatively fast, low amplitude interactions in the thalamocortical system), and phenomenal (for example, consciousness involves the existence of a private flow of events available only to the experiencing subject). While no theory accounts fully for all of these properties at present, we find that ND and its recent extensions fare well. (shrink)

Phenomenal awareness, the ability to be aware of one's sensations and feelings, emerges from the capacity of evolved brains to represent their own cognitive processes by iterating and self-reapplying the cortical operations that generate representations of the outer world. Search for the neuronal substrate of awareness therefore converges with the search for the neuronal code through which brains represent their environment. The hypothesis is put forward that the mammalian brain uses two complementary representational strategies. One consists of the generation of (...) neurons responding selectively to particular constellations of features, and is based on selective recombination of inputs in hierarchically structured feed-forward architectures. The other relies on the dynamic association of large numbers of distributed neurons into functionally coherent cell assemblies which as a whole represent a content of cognition. Arguments and data are presented in favor of the second strategy as the one according to which meta-representations that support awareness are established. My hypothesis is that such distributed representations self-organize through transient synchronization of the oscillatory activity. Evidence showing that similar brain states are required both for the occurrence of these synchronization phenomena and for awareness is provided. (shrink)

In the mid of nineteenth century, the hypothesis, “machine can think,” became very popular after Alan Turing’s article on “Computing Machinery and Intelligence.” This hypothesis, “machine can think,” established the foundations of machine intelligence and claimed that machines have a mind. It has the power to compete with human beings. In the first section, I shall explore the importance of Turing thesis, which has been conceptualized in the domain of machine intelligence. Turing presented a completely different view of the machine (...) itself. It addressed philosophers, rather than the mathematicians, and proclaimed that digital computers might be considered as intelligent machines. This approach was wholly new, both philosophically and technically, and started many philosophical debates which continue to this day. He proposed an imitation game, as a test, what is now referred to as a Turing test to evaluate if a machine thinks. That is to say that the main aim of machine intelligence not only constructs challenging programs to solve our day-to-day problems but also reproduce mentality in machines and claimed that all the mental qualities are ascribable to machines. What will be attempted in this paper is a critical evaluation of the arguments against the Turing test put forward by many philosophers. (shrink)

Several authors within psychology, neuroscience and philosophy take for granted that standard empirical research techniques are applicable when studying consciousness. In this article, it is discussed whether one of the key methods in cognitive neuroscience – the contrastive analysis – suffers from any serious confounding when applied to the field of consciousness studies; that is to say, if there are any systematic difficulties when studying consciousness with this method that make the results untrustworthy. Through an analysis of theoretical arguments in (...) favour of using contrastive analysis, combined with analyses of empirical findings, I conclude by arguing for three factors that currently are confounding of research using contrastive analysis. These are (1) unconscious processes, (2) introspective reports, and (3) attention. (shrink)

This article presents a new conceptual view on the conscious will. This new concept approaches our will from the perspective of the requirements of our neural-muscular system and not from our anthropocentric perspective. This approach not only repositions the will at the core of behavior control, it also integrates the studies of Libet and Wegner, which seem to support the opposite. The will does not return as an instrument we use to steer, but rather as part of the way we (...) learn new automatic behavior and of how our neural system steers us. The new concept suggests that understanding of our will is more about understanding of our daily behavior then about the will itself. (shrink)