A Quantum-mechanical description of ion motion within the confining potentials of voltage gated ion channels

Voltage gated channel proteins cooperate in the transmission of membrane potentials between nerve cells. With the recent progress in atomic-scaled biological chemistry it has now become established that these channel proteins provide highly correlated atomic environments that may maintain electronic coherences even at warm temperatures. Here we demonstrate solutions of the Schr\"{o}dinger equation that represent the interaction of a single potassium ion within the surrounding carbonyl dipoles in the Berneche-Roux model of the bacterial \textit{KcsA} model channel. We show that, depending on the surrounding carbonyl derived potentials, alkali ions can become highly delocalized in the filter region of proteins at warm temperatures. We provide estimations about the temporal evolution of the kinetic energy of ions depending on their interaction with other ions, their location within the oxygen cage of the proteins filter region and depending on different oscillation frequencies of the surrounding carbonyl groups. Our results provide the first evidence that quantum mechanical properties are needed to explain a fundamental biological property such as ion-selectivity in trans-membrane ion-currents and the effect on gating kinetics and shaping of classical conductances in electrically excitable cells.Comment: 12 pages, 8 figure

Social Media and Social Transformation Movements: The Role of Affordances and Platforms

Social media (SM) have played a critical role in recent social transformation movements and yet information systems (IS) literature has only sparsely examined the role of particular SM platforms and their affordances that facilitate such collective action, and how such affordances are appropriated for decentralised forms of collaboration and cooperation. We draw on theories of affordances and collective action to identify a range of functional SM affordances, and related SM platforms, impacting online activism in the recent social transformation movements in Egypt, based on field interviews with a variety of movement participants. We identify nine perceived affordances of SM that were instrumental during the social transformation movements. When these affordances are appropriated by movement participants, they interact with and complement each other, thereby significantly impacting mobilization for social change. Our findings provide a more nuanced perspective on the role of SM in social transformation movements and have implications for both IS and collective action theories

An Enduring Challenge: The Structure-Function Relation in the Brain and the ‘Very Large Brain Projects’

Editorial: THE VERY LARGE BRAIN PROGRAM

From connective actions in social movements to offline collective actions: an individual level perspective

The purpose of this study is to investigate the role of connective action characterised by interconnection and personal communication on social media (SM) for participating in collective action in the physical world of social movements

A Comparative Analysis of Social Media Platforms and the Effects of the Internet Cut-Off for Egypt’s Social Transformation Movements (Best Paper Award)

Social media have been implicated in the recent social movements in much of the Arab world. This study examines the use of social media (SM) platforms, namely Facebook, YouTube and Twitter, in the movements that took place in Egypt during 2011-2013. In particular, we explore the relative usefulness of SM affordances for each platform and relate to affordances that were reported to be significant during Egypt’s social transformation movement in a previous study. We also investigate usage levels for each platform over the period of our study and examine how SM users perceived the effects of the Internet cut-off, which blocked access to these platforms for several days at a critical point in the movement. We do so using a survey of university students, who formed a significant group in Egypt’s social movements

Linoleic acid: Is this the key that unlocks the quantum brain? Insights linking broken symmetries in molecular biology, mood disorders and personalistic emergentism

In this paper we present a mechanistic model that integrates subneuronal structures, namely ion channels, membrane fatty acids, lipid rafts, G proteins and the cytoskeleton in a dynamic system that is finely tuned in a healthy brain. We also argue that subtle changes in the composition of the membrane's fatty acids may lead to down-stream effects causing dysregulation of the membrane, cytoskeleton and their interface. Such exquisite sensitivity to minor changes is known to occur in physical systems undergoing phase transitions, the simplest and most studied of them is the so-called Ising model, which exhibits a phase transition at a finite temperature between an ordered and disordered state in 2- or 3-dimensional space. We propose this model in the context of neuronal dynamics and further hypothesize that it may involve quantum degrees of freedom dependent upon variation in membrane domains associated with ion channels or microtubules. Finally, we provide a link between these physical characteristics of the dynamical mechanism to psychiatric disorders such as major depression and antidepressant action

Brain Geometry and its Relation to Migratory Behavior in Birds

A central concern in neuroscience can simply be brought down to the question of how a brains organization relates to its great diversity of functions. It is generally agreed that this relation must be based on multiscale organizational principles, ranging from the macroscopic level of the entire organ down to the cellular and molecular level. The functional correlates may also be seen as hierarchical constructs ranging from phylogenetic constraints and selectable life history traits down to perception, action and cognition. Here we focus on the relationship between macroscopic brain measures and a conspicuous life history variable in many animal species, migration. Migratory songbirds tend to have smaller brains than resident species. However, in the absence of data providing a detailed mapping of variation in brain subdivisions onto variation in migratory behaviour, offering a causal interpretation of the observed difference in brain size is difficult. Here we describe a set of large scale, geometric measures, which, despite different phylogenetic affiliations, discriminate migratory status across multiple avian lineages and eco-geographical regions. We build our investigation on complete, serial-section based, 3-D volumetric reconstructions of telencephalic subdivisions involving four song bird genera, which differ in their migratory status: long distance (more than 3000 km) and modest or no (0-3000 km) migratory behaviour. Our findings suggest that migratory behaviour as a population level trait can be discriminated at the level of geometrical forebrain measures. We finally discuss the results with respect to the developmental patterns that are largely responsible for the observed differences in brain geometries

The parvocellular vasotocin system of Japanese quail: a developmental and adult model for the study of influences of gonadal hormones on sexually differentiated and behaviorally relevant neural circuits.

Vasotocin (VT; the antidiuretic hormone of birds) is synthesized by diencephalic magnocellular neurons projecting to the neurohypophysis. A sexually dimorphic system of VT-immunoreactive (ir) parvocellular elements has been described within the male medial preoptic nucleus (POM) and the nucleus of the stria terminalis, pars medialis (BSTm). VT-ir fibers are present in many diencephalic and extradiencephalic locations, and quantitative morphometric analyses demonstrated their sexually dimorphic distribution in regions involved in the control of different aspects of reproduction. Moreover, systemic or intracerebroventricular injections of VT markedly inhibit the expression of some aspects of male sexual behavior. In adult animals, circulating levels of testosterone (T) have a profound influence on the VT immunoreactivity within BSTm, POM, and lateral septum. Castration markedly decreases the immunoreaction, whereas T-replacement therapy restores a situation similar to the intact birds. We observed no changes in gonadectomized females treated with T. These changes parallel similar changes in male copulatory behavior (not present in castrated male quail, fully expressed in castrated, T-treated males). The restoration by T of the VT immunoreactivity in castrated male quail could be fully mimicked by a treatment with estradiol (E(2)), suggesting that the aromatization of T into E(2) may play a key limiting role in both the activation of male sexual behavior and the induction of VT synthesis. This dimorphism has an organizational nature: administration of E(2) to quail embryos (a treatment that abolishes male sexual behavior) results in a dramatic decrease of the VT immunoreactivity in sexually dimorphic regions. Conversely, the inhibition of E(2) synthesis during embryonic life (a treatment that stimulates the expression of male copulatory behavior in treated females exposed in adulthood to T) results in a malelike distribution of VT immunoreactivity. The VT parvocellular system of the Japanese quail can therefore be considered an accurate marker of the sexual differentiation of brain circuits mediating copulatory behavior and could be a very sensitive indicator of the activity of estrogenlike substances on neural circuits

Cytoskeletal Signaling: Is Memory Encoded in Microtubule Lattices by CaMKII Phosphorylation?

Memory is attributed to strengthened synaptic connections among particular brain neurons, yet synaptic membrane components are transient, whereas memories can endure. This suggests synaptic information is encoded and ‘hard-wired’ elsewhere, e.g. at molecular levels within the post-synaptic neuron. In long-term potentiation (LTP), a cellular and molecular model for memory, post-synaptic calcium ion (Ca2+) flux activates the hexagonal Ca2+-calmodulin dependent kinase II (CaMKII), a dodacameric holoenzyme containing 2 hexagonal sets of 6 kinase domains. Each kinase domain can either phosphorylate substrate proteins, or not (i.e. encoding one bit). Thus each set of extended CaMKII kinases can potentially encode synaptic Ca2+ information via phosphorylation as ordered arrays of binary ‘bits’. Candidate sites for CaMKII phosphorylation-encoded molecular memory include microtubules (MTs), cylindrical organelles whose surfaces represent a regular lattice with a pattern of hexagonal polymers of the protein tubulin. Using molecular mechanics modeling and electrostatic profiling, we find that spatial dimensions and geometry of the extended CaMKII kinase domains precisely match those of MT hexagonal lattices. This suggests sets of six CaMKII kinase domains phosphorylate hexagonal MT lattice neighborhoods collectively, e.g. conveying synaptic information as ordered arrays of six “bits”, and thus “bytes”, with 64 to 5,281 possible bit states per CaMKII-MT byte. Signaling and encoding in MTs and other cytoskeletal structures offer rapid, robust solid-state information processing which may reflect a general code for MT-based memory and information processing within neurons and other eukaryotic cells