Dicke models are important caricatures of non-relativistic quantum electrodynamics (QED). The rigorous results on superradiance in closed and open Dicke models achieved 50 years ago by Lieb and Hepp still drive modern experimental and theoretical research in cavity QED and will be reviewed in this essay, together with more recent developments.

Kant (1724–1804) is rarely mentioned in modern neuroscience publications, and equally rarely are insights from the neurosciences discussed in works on Kantian philosophy. In this essay I present a correlation, not a confrontation, between Kant in the ‘Critique of Pure Reason’ and the neurosciences on space, time, categories, mechanics, and consciousness in order to highlight their mutual importance. My conclusion will be that Kant is still important for modern neuroscience, although historically he lacked all relevant data and concepts about the brain, and that the insights from neuroscience are equally important for philosophy.

We study whether the transition from wakefulness to light sleep is a synergetic phase transition in the brain.

Reading is a highly complex task involving precise integration of vision, attention, rapid eye movements, and high-level language processing. In the past my colleagues and I [6, 7] have constructed a biologically realistic model of the frontal eye fields that simulates the control of eye movements in human readers. The model couples processes of oculomotor control and cognition in a microcircuit of spiking neurons. In this talk I will use this model to give an introduction to neuro-linguistics with special emphasis on reading and understanding in geometry [10].

This article reviews (II) Mind and Nature: Selected Writings on Philosophy, Mathematics, and Physics Hermann Weyl. 272 pp. , Princeton, NJ, 2009. Price: $35.00(cloth). ISBN 978-0-691-13545-6.

Reading is a highly complex task involving a precise integration of vision, attention, saccadic eye movements, and high-level language processing. Although there is a long history of psychological research in reading, it is only recently that imaging studies have identified some neural correlates of reading. Thus, the underlying neural mechanisms of reading are not yet understood. One very practical requirement of reading is that eye movements be precisely controlled and coordinated with the cognitive processes of reading. Here we present a biologically realistic model of the frontal eye fields that simulates the control of eye movements in human readers. The model couples processes of oculomotor control and cognition in a realistic cortical circuit of spiking neurons. A global rule that signals either "reading" or "not reading" switches the network's behavior from reading to scanning. In the case of reading, interaction with a cortical module that processed "words" allowed the network to read efficiently an array of symbols, including skipping of short words. Word processing and saccade buildup were both modeled by a race to threshold. In both reading and scanning, the network produces realistic distributions of fixation times when compared with human data.

Synapses can only be morphologically identified by electron microscopy and this is often a very labor-intensive and time-consuming task. When quantitative estimates are required for pathways that contribute a small proportion of synapses to the neuropil, the problems of accurate sampling are particularly severe and the total time required may become prohibitive. Here we present a sampling method devised to count the percentage of rarely occurring synapses in the neuropil using a large sample (similar to 1000 sampling sites), with the strong constraint of doing it in reasonable time. The strategy, which uses the unbiased physical disector technique, resembles that used in particle physics to detect rare events.We validated our method in the primary visual cortex of the cat, where we used biotinylated dextran amine to label thalamic afferents and measured the density of their synapses using the physical disector method. Our results show that we could obtain accurate counts of the labeled synapses, even when they represented only 0.2% of all the synapses in the neuropil. (C) 2009 Elsevier B.V. All rights reserved.

In this essay we are searching for neural correlates of ‘doing mathematical physics’. We introduce a toy model of a mathematical physicist, a brain connected with the outside world only by vision and saccadic eye movements and interacting with a computer screen. First, we describe the neuroanatomy of the visuo-saccadic system and Listing’s law, which binds saccades and the optics of the eye. Then we explain space-time transformations in the superior colliculus, the performance of a canonical cortical circuit in the frontal eye field and finally the recurrent interaction of both areas, which leads to a coherent percept of space in spite of saccades. This sets the stage in the brain for doing mathematical physics, which is analyzed in simple examples.

This paper describes the interactive tactile luminous floor that was constructed and used as the skin of the playful interactive space Ada, which ran as a public exhibit for five months in 2002 and had over 550,000 visitors. Ada's floor was custom-built to provide a means for individual and collective user interaction. It consists of 360 hexagonal 66 cm tiles covering a total area of 136 m(2), each with analogue tactile load sensors based on force-sensitive resistors and dimmable neon red, green and blue (RGB) lamps. The tiles are constructed from extruded aluminum with glass tops. An Interbus factory automation bus senses and controls the tiles. Software is described for rendering fluid, dynamic visual effects on the floor, for signal processing of the load information, for real-time visitor tracking and for a variety of behavioural modes, games and interactions. Data from single tiles and from tracking are shown. This floor offers new modalities of human-computer interaction and human-robot interaction for autonomous robotic spaces. (c) 2007 Elsevier B.V. All rights reserved.

The cortical control of eye movements is highly sophisticated. Not only can eye movements be made to the most salient target in a visual scene, but they can also be controlled by top-down rules as is required for visual search or reading. The cortical area called frontal eye fields (FEF) has been shown to play a key role in the visual to oculomotor transformations in tasks requiring an eye movement pattern that is not completely reactive, but follows a previously learned rule. The layered, local cortical circuit, which provides the anatomical substrate for all cortical computation, has been studied extensively in primary sensory cortex. These studies led to the concept of a "canonical circuit" for neocortex (Douglas et al., 1989; Douglas and Martin, 1991), which proposes that all areas of neocortex share a common basic circuit. However, it has not ever been explored whether in principle the detailed canonical circuit derived from cat area 17 (Binzegger et al., 2004) could implement the quite different functions of prefrontal cortex. Here, we show that the canonical circuit can, with a few modifications, model the primate FEF. The spike-based network of integrate-and-fire neurons was tested in tasks that were used in electrophysiological experiments in behaving macaque monkeys. The dynamics of the model matched those of neurons observed in the FEF, and the behavioral results matched those observed in psychophysical experiments. The close relationship between the model and the cortical architecture allows a detailed comparison of the simulation results with physiological data and predicts details of the anatomical circuit of the FEF.

The relationship between quantum mechanics and higher brain functions is an entertaining topic at parties between a mixed, open-minded group of academics. It is, however, also a frequently asked question at international scientific conferences, in funding agencies and sometimes at the end of our lives, when thinking about ultimate truths. Therefore a well-founded understanding of these issues is desirable. The role of quantum mechanics for the photons received by the eye and for the molecules of life is not controversial. The critical questions we are here concerned with is whether any components of the nervous system-a 300 o Kelvin wet and warm tissue strongly coupled to its environment-display any macroscopic quantum behaviors, such as quantum entanglement, and whether such quantum computations have any useful functions to perform. Neurobiologists and most physicists believe that on the cellular level, the interaction of neurons is governed by classical physics. A small minority, however, maintains that quantum mechanics is important for understanding higher brain functions, e.g. for the generation of voluntary movements (free will), for high-level perception and for consciousness. Arguments from biophysics and computational neuroscience make this unlikely. 2 1. Introduction After outlining the problem in brain science and in psychology that some scholars seek to address through quantum mechanics (QM), we outline two arguments that make this unlikely. Firstly, it is unclear what computational advantage QM would provide to the brain over those associated with classical physics. Secondly, as the brain is a hot and wet environment, decoherence will rapidly destroy any macroscopic quantum superposition. Quantum Mechanics Quantum mechanics is, in the framework of this essay, the basic theory of all low-energy phenomena for bodies and brains at home and in the laboratory, e.g. for a human lying in a magnetic resonance scanner in an neuropsychological experiment. Hence, QM is the well-established non-relativistic 'text-book theory' of atoms, electrons and photons, below the energy for pair creation of massive particles (see e.g. Gottfried and Yan 2003). In contrast to classical physics and to that other great edifice of modern physics, general relativity, QM is fundamentally non-deterministic. It explains a range of phenomena that cannot be understood within a classical context: light or any small object can behave like a wave or like a particle depending on the experimental setup (wave-particle duality); the position and the momentum of an object cannot both be simultaneously determined with perfect accuracy (Heisenberg uncertainty-principle); and the quantum states …

Does the enormous computing power of neurons mean consciousness can be explained within a purely neurobiological framework, or is there scope for quantum computation in the brain?

We present a neuromorphic pattern generator for controlling the walking gaits of four-legged robots which is inspired by central pattern generators found in the nervous system and which is implemented as a very large scale integrated (VLSI) chip. The chip contains oscillator circuits that mimic the output of motor neurons in a strongly simplified way. We show that four coupled oscillators can produce rhythmic patterns with phase relationships that are appropriate to generate all four-legged animal walking gaits. These phase relationships together with frequency and duty cycle of the oscillators determine the walking behavior of a robot driven by the chip, and they depend on a small set of stationary bias voltages. We give analytic expressions for these dependencies. This chip reduces the complex, dynamic inter-leg control problem associated with walking gait generation to the problem of setting a few stationary parameters. It provides a compact and low power solution for walking gait control in robots.

—This paper describes the hardware and software engineering of the novel tactile luminous floor and how the floor is used as the skin of the playful interactive space Ada, which ran as a public exhibit for five months in 2002 and had 550,000 visitors. Ada's floor consisted of 360 hexagonal 66-cm tiles covering a total area of 136 m 2 , each with tactile load sensors and dimmable neon red, green, and blue (RGB) lamps. They were constructed from extruded aluminum with glass tops. A factory automation bus sensed and controlled the tiles. This paper also discusses software for generating visual effects on the floor, for signal processing of the load information, for tracking visitors, and for a variety of games and interactions. Data from single tiles and from tracking are shown.

We have discussed in considerable detail a microscopic quantum mechanical model for a laser cavity coupled to different reservoirs and have given a precise sense in which the laser shows irreversible classical and stochastic behavior in the thermodynamic limit. We have, however, only barely prodded the sleeping giant of nonequilibrium statistical mechanics. There are many open problems in this field, both of a technical and conceptual nature. There is the immediate question, whether the choice of the reservoirs, in particular the use of regular Hamiltonians and nonlinear couplings, can qualitatively change the phase transition in this class of mean field models. A nontrivial generalization of our approach is necessary in order to treat the finite mode laser. Our results on the intensive and fluctuation observables are the first two terms in an asymptotic expansion for large finite lasers. It is not clear how good this expansion is, if one is interested in the equilibrium properties of the finite nonlinear system for t→∞. Hopefully, the two limits, N→∞ and t→∞, can be exchanged for certain observables away from threshold. Finally, it is clear that the really hard problems of irreversible statistical mechanics are not the construction of quantum mechanical cuckoo clocks but the understanding of continuous systems with short range and Coulomb forces.

While much is now known about the operation and organisation of the brain at the neuronal and microcircuit level, we are still some way from understanding it as a complete system from the lowest to the highest levels of description. One way to gain such an integrative understanding of neural systems is to construct them. We have built the largest neuromorphic system yet known, an interactive space called 'Ada' that is able to interact with many people simultaneously using a wide variety of sensory and behavioural modalities. 'She' received 553,700 visitors over 5 months during the Swiss Expo.02 in 2002. In this paper we present the broad motivations, design and technologies behind Ada, and discuss the construction and analysis of the system.