Capture of fixation by rotational flow; a deterministic hypothesis regarding scaling and stochasticity in fixational eye movements.

Visual scan paths exhibit complex, stochastic dynamics. Even during visual fixation, the eye is in constant motion. Fixational drift and tremor are thought to reflect fluctuations in the persistent neural activity of neural integrators in the oculomotor brainstem, which integrate sequences of transient saccadic velocity signals into a short term memory of eye position. Despite intensive research and much progress, the precise mechanisms by which oculomotor posture is maintained remain elusive. Drift exhibits a stochastic statistical profile which has been modeled using random walk formalisms. Tremor is widely dismissed as noise. Here we focus on the dynamical profile of fixational tremor, and argue that tremor may be a signal which usefully reflects the workings of oculomotor postural control. We identify signatures reminiscent of a certain flavor of transient neurodynamics; toric traveling waves which rotate around a central phase singularity. Spiral waves play an organizational role in dynamical systems at many scales throughout nature, though their potential functional role in brain activity remains a matter of educated speculation. Spiral waves have a repertoire of functionally interesting dynamical properties, including persistence, which suggest that they could in theory contribute to persistent neural activity in the oculomotor postural control system. Whilst speculative, the singularity hypothesis of oculomotor postural control implies testable predictions, and could provide the beginnings of an integrated dynamical framework for eye movements across scales

Bilateral gain control; an "innate predisposition" for all sorts of things.

Empirical studies have revealed remarkable perceptual organization in neonates. Newborn behavioral distinctions have often been interpreted as implying functionally specific modular adaptations, and are widely cited as evidence supporting the nativist agenda. In this theoretical paper, we approach newborn perception and attention from an embodied, developmental perspective. At the mechanistic level, we argue that a generative mechanism based on mutual gain control between bilaterally corresponding points may underly a number of functionally defined "innate predispositions" related to spatial-configural perception. At the computational level, bilateral gain control implements beamforming, which enables spatial-configural tuning at the front end sampling stage. At the psychophysical level, we predict that selective attention in newborns will favor contrast energy which projects to bilaterally corresponding points on the neonate subject's sensor array. The current work extends and generalizes previous work to formalize the bilateral correlation model of newborn attention at a high level, and demonstrate in minimal agent-based simulations how bilateral gain control can enable a simple, robust and "social" attentional bias

Hanging in there: Prenatal origins of antigravity homeostasis in humans

All life on Earth must find a way to manage the continuous perturbation of gravity. From birth, and even before, humans exhibit effortful antigravity work to enact bodily, postural and behavioural form despite gravity. Indeed, observable antigravity behaviour is a standard diagnostic indicator of neonatal sensorimotor health. Antigravity behaviour has been investigated extensively in its biomechanical details. Yet its motivational structure has not been a focus of research. What drives the human body to expend energy on this effortful behaviour? It is widely understood that thermic homeostasis in humans is organised around conserving core body temperature at a set-point of 36.5-37.5oC. There is currently no equivalent concept of a general homeostatic set-point driving antigravity effort. In this theoretical paper, we aim to establish such a concept. We make the case that the core developmental set-point for human antigravity homeostasis is neutral buoyancy (gravity and buoyant force are balanced), which is afforded to the foetus by its approximately equi-dense amniotic fluid medium in utero. We argue that postnatally, the general task of human antigravity balance is to emulate the conditions of neutral buoyancy, based upon prenatal experience thereof. Our aim in this paper is to sketch a high-level outline of a novel characterisation of antigravity balance as conservative homeostasis, and lay out some implications and predictions of this model, with the intention of spurring wider research and discussion on this hitherto little explored topic. Keywords: antigravity, posture, homeostasis, prenatal, buoyancy, density, fetus, foetusComment: 19 pages (including references) Zero figure

Construction and properties of a mutant of herpes simplex virus type 1 with glycoprotein H coding sequences deleted

A mutant of herpes simplex virus type 1 (HSV-1) in which glycoprotein H (gH) coding sequences were deleted and replaced by the Escherichia coli lacZ gene under the control of the human cytomegalovirus IE-1 gene promoter was constructed. The mutant was propagated in Vero cells which contained multiple copies of the HSV-1 gH gene under the control of the HSV-1 gD promoter and which therefore provide gH in trans following HSV-1 infection. Phenotypically gH-negative virions were obtained by a single growth cycle in Vero cells. These virions were noninfectious, as judged by plaque assay and by expression of I-galactosidase following high-multiplicity infection, but partial recovery of infectivity was achieved by using the fusogenic agent polyethylene glycol. Adsorption of gH-negative virions to cells blocked the adsorption of superinfecting wild-type virus, a result in contrast to that obtained with gD-negative virions (D. C. Johnson and M. W. Ligas, J. Virol. 62:4605-4612, 1988). The simplest conclusion is that gH is required for membrane fusion but not for receptor binding, a conclusion consistent with the conservation of gH in all herpesviruses

FMRP and CYFIP1 at the synapse and their role in psychiatric vulnerability

There is increasing awareness of the role genetic risk variants have in mediating vulnerability to psychiatric disorders such as schizophrenia and autism. Many of these risk variants encode synaptic proteins, influencing biological pathways of the postsynaptic density and, ultimately, synaptic plasticity. Fragile X Mental Retardation 1 (FMR1) and Cytoplasmic FRMP-Interacting Protein (CYFIP1) contain two such examples of highly penetrant risk variants and encode synaptic proteins with shared functional significance. In this Review, we will discuss the biological actions of FMRP and CYFIP1, including their regulation of i) protein translation and specifically FMRP targets, ii) dendritic and spine morphology and iii) forms of synaptic plasticity such as long-term depression. We draw upon a range of preclinical studies that have used genetic dosage models of FMR1 and CYFIP1 to determine their biological function. In parallel, we discuss how clinical studies of Fragile X Syndrome or 15q11.2 deletion patients have informed our understanding of FMRP and CYFIP1 proteins, and highlight the latest psychiatric genomic findings that continue to implicate FMRP and CYFIP1. Lastly, we assess the current limitations in our understanding of FMRP and CYFIP1 biology and how they must be addressed before mechanism-led therapeutic strategies can be developed for psychiatric disorders

Use of mobile apps for teaching and research - implications for digital literacy

This paper reports on the results of an online survey about mobile application (app) use for academic purposes, i.e. teaching and research, by Higher Degree Research (HDR) students and academic staff at one of the eight New Zealand universities. Two thirds of the 138 respondents reported they used apps for academic purposes. In teaching, apps were reported to be used as a means to push information to students. In research, apps appeared to be used to self-organise, collaborate with colleagues, store information, and to stay current with research. This paper presents the survey results and discusses implications for personal information management in education context and opportunities for university library services

‘This is our treehouse’ : Investigating play through a practice architectures lens

This article explores a child-led project of building a treehouse through the theory of practice architectures. It draws on video data collected by 13 children wearing microcameras (GoPro) in a multicultural Australian primary school. The data was co-analysed with the children. The article illuminates how play practices emerge, diffuse, persist and/or disappear with time. This knowledge is needed to understand the different facets of free play and build enabling conditions for its unfolding.publishedVersionPeer reviewe