This paper examines the impact that recent advances in clinical neurology, introspectionist psychology and neuroscience have upon the philosophical psycho?neural Identity Theory. Topics covered include (i) the nature and properties of phenomenal consciousness based on a study of the ?basic? visual field, i.e. that obtained in the complete dark, the Ganzfeld, and during recovery from occipital lobe injuries; (ii) the nature of the ?body?image? of neurology and its relation to the physical body; (iii) Descartes? error in choosing extension in space (...) as the criterion for distinguishing the physical and the mental; (iv) the technical distinction between sensing and perceiving; (v) why phenomenal Direct Realism is incorrect whereas epistemic DR and the representative theory are correct; (vi) the ontological and topological status of phenomenal space and physical space. This leads to considerations of the current ?binding problems? in neuroscience; the role of the brain mechanisms that construct the sensory fields of phenomenal consciousness; the ?homunculus? fallacy; the key difference between epistemic and non?epistemic perception as revealed by brain injury studies; and how the brain codes information, contrasting topological and vectorial coding, with particular reference to the binding problem. My conclusion is that the Identity Theory is incompatible with the scientific evidence from an integrated approach to modern introspectionist psychology, clinical neurology, and neuroscience. However, Cartesian Dualism is even more incompatible with the evidence. This leaves only two viable theories. The first is Bohr's theory of brain?consciousness complementarity. The second is the Broad?Price?Smythies theory of extension, which is a topological theory of the relation between phenomenal space and physical space. (shrink)
There are currently two main philosophical theories of perception - Direct Realism and the Representative Theory. The former is supported by most contemporary philosophers, whereas the latter forms the groundwork for most scientific theories in this area. The paper describes a recent experiment involving retinal and cortical rivalry that provides strong empirical evidence that the Direct Realist theory is incorrect. There are of course a large number of related experiments on visual perception that would tend to lead us to the (...) same conclusion, but the experiment described in this paper does so in a singularly direct and straightforward manner. Often the most telling experiments are the simplest. (shrink)
This paper focuses on perception and surveys the scientific evidence that the theory of direct realism adopted by most contemporary philosophers is incorrect. This evidence is provided by experiments on the spatial and temporal "filling-in" of percepts. It also examines the myth of the projection of sensations. The conclusion is that we do not perceive the world as it actually is, but as the brain computes it most probably to be.
Current research on the neural basis of consciousness is based mainly on neuroimaging, physiology and psychophysics. This target article reviews what is known about biochemical factors that may contribute to the development of consciousness, based on loss of consciousness (i.e., coma). There are two theories of the biochemical mode of action of general anaesthetics. One is that anaesthesia is a direct (i.e., not receptor-mediated) effect of the anaesthetic on cellular neurophysiological function; the other is that some alteration of receptor function (...) occurs. General anaesthetics are mainly GABA agonists but some (such as ketamine) are glutamate antagonists. They also affect other systems, particularly cholinergic ones. There are various comas of metabolic origin. For example, a combination of small doses of the iron chelators desferrioxamine and prochlorperazine induce a profound and long lasting coma in humans. The mechanisms that might mediate this include redox mechanisms at the glutamate synapse, post-synaptic endocytosis of dopamine and iron, and intracellular iron-dopamine complexes, which are powerful dismuters of the superoxide anion. New findings in cell biology relating to endocytosis and recycling of receptors are discussed in a wider context. These biochemical events may induce coma by two mechanisms: (i) Consciousness may depend on widespread cortical (or cortico-thalamic) activation. (ii) Whereas these biochemical changes are widespread, only the changes in a subset of consciousness' neurons may count. An experimental program to distinguish between these two alternatives is proposed. (shrink)
Presenting some modern views on the problem of the nature of mind and its relationship to the brain, this book, published in 1965, brings together contributors from various disciplines which are affected by this issue. Coming from different philosophical outlooks as well as subjects, these contributors also comment on each other’s’ chapters with a view of developing thought on the approaches to the problem. The theory of mind-brain relationship is vital to human interest and has been in debate throughout western (...) thought over centuries, split mainly into dualist and monistic theories. These discussions had and still have wide impact philosophy, psychology, religion and cosmology, among other areas. (shrink)