Information processing in microtubules

Physics and the quandaries of contemporary psychiatry: review and research

Although in physics, quantum mechanical principles have long replaced Newtonian ones, we continue to apply the latter in models of the mind and its diseases. This article discusses the possible theoretical application of quantum principles to mind-brain function. Empirically, this study tested which of these principles practicing psychiatrists found more applicable in clinical practice. Psychiatrists (N = 382) at universities around the United States were asked to answer a questionnaire that contained clinical scenarios reflecting mental, interpersonal, or therapeutic processes corresponding to quantum or classical physical principles. Respondents (N = 191) were significantly more likely to rate scenarios reflecting quantum principles as being consistent with their experience than they were those reflecting classical principles (p < .0005). This effect was significantly greater in more experienced psychiatrists. Quantum physics, a powerful tool in understanding properties of both micro- and macro-level phenomena, may have implications at the human level, invoking the roles of observer, interpersonal relationships, and resources such as resiliency and creativity.

Molecular automata assembly: principles and simulation of bacterial membrane construction

The motivation to understand the basic rules and principles governing molecular self-assembly may be relevant to explain in the context of molecular biology the self-organization and biological functions exhibited within cells. This paper presents a molecular automata model to simulate molecular self-assembly introducing the concept of molecular programming to simulate the biological function or operation performed by an assembled molecular state machine. The method is illustrated modelling Escherichia coli membrane construction including the assembly and operation of ATP synthase as well as the assembly of the bacterial flagellar motor. Flagellar motor operation was simulated using a different approach based on state machine definition used in virtual reality systems. The proposed methodology provides a modelling framework for simulation of biological functions performed by cellular components and other biological systems suitable to be modelled as molecular state machines.

The state of consciousness and very high frequency signalling in the serotonergic neuronal system

The attributes of consciousness are briefly discussed and matched to the known characteristics of the serotonergic neuronal system. In particular sleep, the action of agonist drugs, the regulatory role and monitoring components, together with the receptor areas for serotonergic activity, are identified as significant correlates of consciousness. Fröhlich-like phenomena are attributed to the topology of the serotonergic cell which is posited to produce excitations in the gigaHz or very high frequency range. Coding by discrete channel frequency and propagation throughout the vast microtubule cytoskeletal structure of serotonergic activity is proposed as the biophysical basis of consciousness in higher mammals, particularly humans.

Selected physical issues in the structure and function of microtubules

The cytoskeleton consists of networks of protein polymers which structurally and dynamically organize interiors of living cells. Microtubules exhibit a complex array of self-organization phenomena which are very sensitive to various laboratory conditions. In this paper we discuss the main features of microtubules focusing our attention on a selection of their physical properties, i.e., the questions of assembly dynamics and energy transfer along their protofilaments, the possible dipolar phases which we predict to exist, and, finally, the hypothesis of current flows associated with the electric field lines produced by cytoskeletal components.

The enigma of microtubules and their self-organizing behavior in the cytoskeleton

The cytoskeleton of eukaryotic cells contains networks of protein polymers called microtubules which structurally and functionally organize their interiors. Both in vivo and in vitro microtubules exhibit a fascinating and yet poorly understood array of important functions involving complex self-organization phenomena which are very sensitive to physiological and laboratory conditions, respectively. In this paper we discuss the main physical characteristics of microtubules focusing our attention on four particular aspects: (a) the dynamics of their assembly and disassembly processes (b) the types and the range of existence of ordered dipolar phases and (c) modes of energy transfer and (d) information processing capabilities.

Electrodynamics of microtubular motors: the building blocks of a new model

Microtubules are ubiquitous components of the cytoskeleton. They participate in many motility processes ranging from intracellular transport or chromosome movement during mitosis to ciliary and flagellar beating. The biophysical mechanism inherent in the generation and control of movement in all these motility phenomena has not yet been entirely elucidated. The authors propose a new model based on a charge transfer mechanism capable of shedding a new light on the molecular foundations of all motility processes. Electron transfer along the microtubular lattice is responsible for activation and control of all microtubule-associated ATPases (i.e. force generating enzymes). Microtubules are thus shown to be the basic motors of cell dynamics. The model is first applied to intracellular transport and ciliary and flagellar beating. Through two additional examples, the authors show the heuristic capabilities of the suggested hypothesis. The application of charge transfer control to the Protozoan Euglena gracilis leads to a plausible model capable of accounting for its phototactic response mechanism. Furthermore, the model allows a new interpretation of the electrophysiological response in vertebrate photoreceptors.

The change of microtubule length caused by endogenous AC fields in cell

In this paper we investigate the change of microtubule cylinder's length in the presence of endogenous AC fields generated by the cell itself. The dynamics of microtubule is described on the basis of classical u4 model. The average stretching is calculated by using Kubo's formalism for linear response of system.

Quantum optical coherence in cytoskeletal microtubules: implications for brain function

'Laser-like,' long-range coherent quantum phenomena may occur biologically within cytoskeletal microtubules. This paper presents a theoretical prediction of the occurrence in biological media of the phenomena which we term 'superradiance' and 'self-induced transparency'. Interactions between the electric dipole field of water molecules confined within the hollow core of microtubules and the quantized electromagnetic radiation field are considered, and microtubules are theorized to play the roles of non-linear coherent optical devices. Superradiance is a specific quantum mechanical ordering phenomenon with characteristic times much shorter than those of thermal interaction. Consequently, optical signalling (and computation) in microtubules would be free from both thermal noise and loss. Superradiant optical computing in networks of microtubules and other cytoskeletal structures may provide a basis for biomolecular cognition and a substrate for consciousness.

The brain-machine disanalogy

The comparative study of information processing in brains and machines leads to a picture in which disanalogies are more fundamental than analogies. The major dichotomy is between evolvability and programmability. Brain models, to be tenable, must pass an extended Turing test in which the capacity to self organize through the Darwinian mechanism of variation and selection is a key element. Programmable machines that simulate the type of structure-function relations that allow evolution to occur are, however, too inefficient in their use of resources for problem solving to support cognitive abilities comparable to those of biological organisms. Furthermore, real evolutionary systems are open in that it is always possible for them to tap previously unexploited physical interactions for computing. Nevertheless, computer simulation provides a powerful tool for studying brain function; and non-programmable designs that exploit the high efficiency, high adaptability domain of computing are in principle possible.