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.

Representationalism is a thesis about the phenomenal character of experiences, about their immediate subjective ‘feel’.1 At a minimum, the thesis is one of supervenience: necessarily, experiences that are alike in their representational contents are alike in their phenomenal character. So understood, the thesis is silent on the nature of phenomenal character. Strong or pure representationalism goes further. It aims to tell us what phenomenal character is. According to the theory developed in Tye 1995, phenomenal character is one and the same (...) as representational content that meets certain further conditions. One very important motivation for this theory is the so-called ? transparency of experience.? The purpose of this paper is to elucidate the appeal to transparency more carefully than has been done hithertofore, to make some remarks about the introspective awareness of experience in light of this appeal, and to consider one problem case for transparency at some length, that of blurry vision. Along the way, I shall also address some of the remarks Stephen Leeds makes in his essay on transparency. (shrink)

A unifying theory of general anesthetic-induced unconsciousness must explain the common mechanism through which various anesthetic agents produce unconsciousness. Functional-brain-imaging data obtained from 11 volunteers during general anesthesia showed specific suppression of regional thalamic and midbrain reticular formation activity across two different commonly used volatile agents. These findings are discussed in relation to findings from sleep neurophysiology and the implications of this work for consciousness research. It is hypothesized that the essential common neurophysiologic mechanism underlying anesthetic-induced unconsciousness is, as with (...) sleep-induced unconsciousness, a hyperpolarization block of thalamocortical neurons. A model of anesthetic-induced unconsciousness is introduced to explain how the plethora of effects anesthetics have on cellular functioning ultimately all converge on a single neuroanatomic/neurophysiologic system, thus providing for a unitary physiologic theory of narcosis related to consciousness. (shrink)

Consciousness and Mind presents David Rosenthal's influential work on the nature of consciousness. Central to that work is Rosenthal's higher-order-thought theory of consciousness, according to which a sensation, thought, or other mental state is conscious if one has a higher-order thought that one is in that state. The first four essays develop various aspects of that theory. The next three essays present Rosenthal's homomorphism theory of mental qualities and qualitative consciousness, and show how that theory fits with and helps sustain (...) the HOT theory. A crucial feature of homomorphism theory is that it individuates and taxonomizes mental qualities independently of the way we're conscious of them, and indeed independently of our being conscious of them at all. So the theory accommodates the qualitative character not only of conscious sensations and perceptions, but also of those which fall outside our stream of consciousness. Rosenthal argues that, because this account of mental qualities makes no appeal to consciousness, it enables us to dispel such traditional quandaries as the alleged conceivability of undetectable quality inversion, and to disarm various apparent obstacles to explaining qualitative consciousness and understanding its nature. Six further essays build on the HOT theory to explain various important features of consciousness, among them the complex connections that hold in humans between consciousness and speech, the self-interpretative aspect of consciousness, and the compelling sense we have that consciousness is unified. Two of the essays, one an extended treatment of homomorphism theory, appear here for the first time. There is also a substantive introduction, which draws out the connections between the essays and highlights their implications. (shrink)

The author takes the reader on a tour that covers such topics as computers, evolution, Descartes, Schrodinger, and the nature of perception, language, and invididuality. He argues that biology provides the key to understanding the brain. Underlying his argument is the evolutionary view that the mind arose at a definite time in history. This book ponders connections between psychology and physics, medicine, philosophy, and more. Frequently contentious, Edelman attacks cognitive and behavioral approaches, which leave biology out of the picture, as (...) well as the currently fashionable view of the brain as a computer. (shrink)

[opening paragraph] -- Clark: The `astonishing hypothesis' which you put forward in your book, and which you obviously feel is very controversial, is that `You, your joys and sorrows, your memories and ambitions, your sense of personal identity and free will are, in fact, no more than the behaviour of a vast assembly of nerve cells. As Lewis Carroll's Alice might have phrased it: `You're nothing but a pack of neurons'.' But it seems to me that this is not so (...) astonishing a statement for a scientist to make. Isn't this what reductionist science has always believed? (shrink)

To make progress on the problem of consciousness, we have to confront it directly. In this paper, I first isolate the truly hard part of the problem, separating it from more tractable parts and giving an account of why it is so difficult to explain. I critique some recent work that uses reductive methods to address consciousness, and argue that such methods inevitably fail to come to grips with the hardest part of the problem. Once this failure is recognized, the (...) door to further progress is opened. In the second half of the paper, I argue that if we move to a new kind of nonreductive explanation, a naturalistic account of consciousness can be given. I put forward my own candidate for such an account: a nonreductive theory based on principles of structural coherence and organizational invariance, and a double-aspect theory of information. (shrink)

Based on neurobiological data, modern concepts of self-organization and a careful rationale, the hypothesis is put forward that the fleeting, highly ordered patterns of electric and/or magnetic fields, generated by assemblies of dendritic trees of specialized neuronal networks, should be thought of as the end-product of chaotic, dynamically governed self-organization. Such patterns encode for subjective experiences such as pain and pleasure, or perceiving colours. Because by quantum mechanical definition virtual photons are the theoretical constituents of electric and magnetic fields, the (...) former hypothesis can be re-formulated as follows: it is the highly ordered patterns of virtual photons that encode for subjective experiences. Arguments are then given that consciousness did not emerge during evolution only after neuronal networks had been formed able to generate electric and/or magnetic fields of sufficient complexity but, rather, that subjectivity already existed in a very elementary form as a fundamental property of the omnipresent virtual photons, i.e., of matter. The contribution of neuronal networks to consciousness was to generate highly ordered patterns of germs of subjectivity , so allowing complex subjective experiences. Due to the omnipresence of virtual photons, it follows finally that the whole universe must be imbued with subjectivity. An experimental strategy is proposed to test the hypothesis. (shrink)