Neural network research often builds on the fiction that neurons are simple linear threshold units, completely neglecting the highly dynamic and complex nature of synapses, dendrites, and voltage-dependent ionic currents. Biophysics of Computation: Information Processing in Single Neurons challenges this notion, using richly detailed experimental and theoretical findings from cellular biophysics to explain the repertoire of computational functions available to single neurons. The author shows how individual nerve cells can multiply, integrate, or delay synaptic inputs and how information can be encoded in the voltage across the membrane, in the intracellular calcium concentration, or in the timing of individual spikes.
Key topics covered include the linear cable equation; cable theory as applied to passive dendritic trees and dendritic spines; chemical and electrical synapses and how to treat them from a computational point of view; nonlinear interactions of synaptic input in passive and active dendritic trees; the Hodgkin-Huxley model of action potential generation and propagation; phase space analysis; linking stochastic ionic channels to membrane-dependent currents; calcium- and potassium-currents and their role in information processing; the role of diffusion, buffering and binding of calcium, and other messenger systems in information processing and storage; short- and long-term models of synaptic plasticity; simplified models of single cells; stochastic aspects of neuronal firing; the nature of the neuronal code; and unconventional models of sub-cellular computation.
Biophysics of Computation: Information Processing in Single Neurons serves as an ideal text for advancedundergraduate and graduate courses in cellular biophysics, computational neuroscience, and neural networks, and will appeal to students and professionals in neuroscience, electrical and computer engineering, and physics.

An argument that consciousness, more widespread than previously assumed, is the feeling of being alive, not a type of computation or a clever hack.In The Feeling of Life Itself, Christof Koch offers a straightforward definition of consciousness as any subjective experience, from the most mundane to the most exalted--the feeling of being alive. Psychologists study which cognitive operations underpin a given conscious perception. Neuroscientists track the neural correlates of consciousness in the brain, the organ of the mind. But why the brain and not, say, the liver? How can the brain, three pounds of highly excitable matter, a piece of furniture in the universe, subject to the same laws of physics as any other piece, give rise to subjective experience? Koch argues that what is needed to answer these questions is a quantitative theory that starts with experience and proceeds to the brain. In The Feeling of Life Itself, Koch outlines such a theory, based on integrated information. Koch describes how the theory explains many facts about the neurology of consciousness and how it has been used to build a clinically useful consciousness meter. The theory predicts that many, and perhaps all, animals experience the sights and sounds of life; consciousness is much more widespread than conventionally assumed. Contrary to received wisdom, however, Koch argues that programmable computers will not have consciousness. Even a perfect software model of the brain is not conscious. Its simulation is fake consciousness. Consciousness is not a special type of computation--it is not a clever hack. Consciousness is about being.

Much research focuses on the question of how information is processed in nervous systems, from the level of individual ionic channels to large-scale neuronal networks, and from "simple" animals such as sea slugs and flies to cats and primates. New interdisciplinary methodologies combine a bottom-up experimental methodology with the more top-down-driven computational and modeling approach. This book serves as a handbook of computational methods and techniques for modeling the functional properties of single and groups of nerve cells.The contributors highlight several key trends: (1) the tightening link between analytical/numerical models and the associated experimental data, (2) the broadening of modeling methods, at both the subcellular level and the level of large neuronal networks that incorporate real biophysical properties of neurons as well as the statistical properties of spike trains, and (3) the organization of the data gained by physical emulation of the nervous system components through the use of very large scale circuit integration (VLSI) technology.The field of neuroscience has grown dramatically since the first edition of this book was published nine years ago. Half of the chapters of the second edition are completely new; the remaining ones have all been thoroughly revised. Many chapters provide an opportunity for interactive tutorials and simulation programs. They can be accessed via Christof Koch's Website.Contributors: Larry F. Abbott, Paul R. Adams, Hagai Agmon-Snir, James M. Bower, Robert E. Burke, Erik de Schutter, Alain Destexhe, Rodney Douglas, Bard Ermentrout, Fabrizio Gabbiani, David Hansel, Michael Hines, Christof Koch, Misha Mahowald, Zachary F. Mainen, Eve Marder, Michael V. Mascagni, Alexander D. Protopapas, Wilfrid Rall, John Rinzel, Idan Segev, Terrence J. Sejnowski, Shihab Shamma, Arthur S. Sherman, Paul Smolen, Haim Sompolinsky, Michael Vanier, Walter M. Yamada.

Bewusstsein - das weiter verbreitet ist als bisher angenommen - ist das Gefuhl, lebendig zu sein, es ist kein Rechenvorgang und auch kein cleverer Trick. In diesem Buch liefert Christof Koch eine schnoerkellose Definition des Bewusstseins als bewusstes Erleben, vom alltaglichsten bis zum aussergewoehnlichsten - eben das Gefuhl zu leben.Die Psychologie erforscht, welche kognitiven Vorgange einer bewussten Wahrnehmung jeweils zugrunde liegen. Die Neurowissenschaft spurt den neuronalen Korrelaten des Bewusstseins im Gehirn nach, dem Organ des Geistes. Aber warum das Gehirn und nicht etwa die Leber oder ein anderes Organ? Wie kann das Gehirn, drei Pfund hoechst erregbares Gewebe, ein Gegenstand im Universum, der denselben physikalischen Gesetzen gehorcht wie jeder andere Gegenstand, subjektives Erleben hervorbringen? Will man eine Antwort auf diese Frage finden, braucht man, so Koch, eine quantitative Theorie, die beim Erleben ansetzt und zum Gehirn fortschreitet. Im vorliegenden Buch umreisst der Autor eine solche Theorie, basierend auf der integrierten Informationstheorie. Koch beschreibt, wie die Theorie viele Fakten zur Neurologie des Bewusstseins erklart und wie man mit ihrer Hilfe sogar ein in der Klinik einsetzbares Bewusstseins-Messgerat konstruiert hat. Die Theorie sagt voraus, dass viele, ja vielleicht alle Tiere das Leben in vielen Facetten erleben; Bewusstsein ist viel weiter verbreitet als allgemein angenommen. Entgegen der landlaufigen Ansicht aber argumentiert Koch, dass programmierbare Computer kein Bewusstsein haben werden. Selbst ein perfektes Softwaremodell des Gehirns ist nicht bewusst - es simuliert lediglich Bewusstsein. Bewusstsein ist keine bestimmte Art von Rechenvorgang, es ist kein cleverer Trick. Bewusstsein ist Sein.reich mit dem Sachbuchprogramm waren.

In which a scientist searches for an empirical explanation for phenomenal experience, spurred by his instinctual belief that life is meaningful. What links conscious experience of pain, joy, color, and smell to bioelectrical activity in the brain? How can anything physical give rise to nonphysical, subjective, conscious states? Christof Koch has devoted much of his career to bridging the seemingly unbridgeable gap between the physics of the brain and phenomenal experience. This engaging book-part scientific overview, part memoir, part futurist speculation-describes Koch's search for an empirical explanation for consciousness. Koch recounts not only the birth of the modern science of consciousness but also the subterranean motivation for his quest-his instinctual (if "romantic") belief that life is meaningful. Koch describes his own groundbreaking work with Francis Crick in the 1990s and 2000s and the gradual emergence of consciousness (once considered a "fringy" subject) as a legitimate topic for scientific investigation. Present at this paradigm shift were Koch and a handful of colleagues, including Ned Block, David Chalmers, Stanislas Dehaene, Giulio Tononi, Wolf Singer, and others. Aiding and abetting it were new techniques to listen in on the activity of individual nerve cells, clinical studies, and brain-imaging technologies that allowed safe and noninvasive study of the human brain in action. Koch gives us stories from the front lines of modern research into the neurobiology of consciousness as well as his own reflections on a variety of topics, including the distinction between attention and awareness, the unconscious, how neurons respond to Homer Simpson, the physics and biology of free will, dogs, Der Ring des Nibelungen, sentient machines, the loss of his belief in a personal God, and sadness. All of them are signposts in the pursuit of his life's work-to uncover the roots of consciousness.