Thomas Graham Brown (1882–1965): Behind the Scenes at the Cardiff Institute of Physiology

Thomas Graham Brown undertook seminal experiments on the neural control of locomotion between 1910 and 1915. Although elected to the Royal Society in 1927, his locomotion research was largely ignored until the 1960s when it was championed and extended by the distinguished neuroscientist, Anders Lundberg. Puzzlingly, Graham Brown's published research stopped in the 1920s and he became renowned as a mountaineer. In this article, we review his life and multifaceted career, including his active neurological service in WWI. We outline events behind the scenes during his tenure at Cardiff's Institute of Physiology in Wales, UK, including an interview with his technician, Terrence J. Surman, who worked in this institute for over half a century

Platinum Nanoparticle Decorated SiO 2 Microfibers as Catalysts for Micro Unmanned Underwater Vehicle Propulsion

Micro unmanned underwater vehicles (UUVs) need to house propulsion mechanisms that are small in size but sufficiently powerful to deliver on-demand acceleration for tight radius turns, burst-driven docking maneuvers, and low-speed course corrections. Recently, small-scale hydrogen peroxide (H2O2) propulsion mechanisms have shown great promise in delivering pulsatile thrust for such acceleration needs. However, the need for robust, high surface area nanocatalysts that can be manufactured on a large scale for integration into micro UUV reaction chambers is still needed. In this report a thermal/electrical insulator, silicon oxide (SiO2) microfibers, are used as a support for platinum nanoparticle (PtNP) catalysts. The mercapto-silanization of the SiO2 microfibers enables strong covalent attachment with PtNPs and the resultant PtNP-SiO2 fibers act as a robust, high surface area catalyst for H2O2 decomposition. The PtNP-SiO2 catalysts are fitted inside a micro UUV reaction chamber for vehicular propulsion; the catalysts can propel a micro UUV for 5.9 meters at a velocity of 1.18 m/s with 50 mL of 50% (w/w) H2O2.The concomitance of facile fabrication, economic and scalable processing, and high performance —including a reduction in H2O2 decomposition activation energy of 40-50% over conventional material catalysts—paves the way for using these nanostructured microfibers in modern, small-scale underwater vehicle propulsion systems

EZH2 promotes a bi-lineage identity in basal-like breast cancer cells

The mechanisms regulating breast cancer differentiation state are poorly understood. Of particular interest are molecular regulators controlling the highly aggressive and poorly differentiated traits of basal-like breast carcinomas. Here we show that the Polycomb factor EZH2 maintains the differentiation state of basal-like breast cancer cells, and promotes the expression of progenitor-associated and basal-lineage genes. Specifically, EZH2 regulates the composition of basal-like breast cancer cell populations by promoting a ‘bi-lineage’ differentiation state, in which cells co-express basal- and luminal-lineage markers. We show that human basal-like breast cancers contain a subpopulation of bi-lineage cells, and that EZH2-deficient cells give rise to tumors with a decreased proportion of such cells. Bi-lineage cells express genes that are active in normal luminal progenitors, and possess increased colony-formation capacity, consistent with a primitive differentiation state. We found that GATA3, a driver of luminal differentiation, performs a function opposite to EZH2, acting to suppress bi-lineage identity and luminal-progenitor gene expression. GATA3 levels increase upon EZH2 silencing, mediating a decrease in bi-lineage cell numbers. Our findings reveal a novel role for EZH2 in controlling basal-like breast cancer differentiation state and intra-tumoral cell composition

Motion processing with wide-field neurons in the retino-tecto-rotundal pathway

The retino-tecto-rotundal pathway is the main visual pathway in non-mammalian vertebrates and has been found to be highly involved in visual processing. Despite the extensive receptive fields of tectal and rotundal wide-field neurons, pattern discrimination tasks suggest a system with high spatial resolution. In this paper, we address the problem of how global processing performed by motion-sensitive wide-field neurons can be brought into agreement with the concept of a local analysis of visual stimuli. As a solution to this problem, we propose a firing-rate model of the retino-tecto-rotundal pathway which describes how spatiotemporal information can be organized and retained by tectal and rotundal wide-field neurons while processing Fourier-based motion in absence of periodic receptive-field structures. The model incorporates anatomical and electrophysiological experimental data on tectal and rotundal neurons, and the basic response characteristics of tectal and rotundal neurons to moving stimuli are captured by the model cells. We show that local velocity estimates may be derived from rotundal-cell responses via superposition in a subsequent processing step. Experimentally testable predictions which are both specific and characteristic to the model are provided. Thus, a conclusive explanation can be given of how the retino-tecto-rotundal pathway enables the animal to detect and localize moving objects or to estimate its self-motion parameters

Visual Evoked Potentials Change as Heart Rate and Carotid Pressure Change

The relationship between cardiovascular activity and the brain was explored by recording visual evoked potentials from the occipital regions of the scalp during systolic and diastolic pressure (Experiment I) and during fast and slow heartbeats at systolic and diastolic pressure (Experiment II). Visual evoked potentials changed significantly as heart rate and carotid pressure fluctuated normally, and these changes were markedly different in the right and left cerebral hemispheres. Evoked potentials recorded from the right hemisphere during various cardiac events differed significantly, whereas those recorded from the left did not. In both experiments, differences in the right hemisphere were due primarily to the P1 component, which was larger at diastolic than at systolic pressure. The present findings are consistent with formulations from behavioral studies suggesting that baroreceptor activity can influence sensory intake, and suggest that hemispheric specialization may play an important role in the relationship between cardiac events, the brain and behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73146/1/j.1469-8986.1982.tb02579.x.pd

Size constancy is preserved but afterimages are prolonged in typical individuals with higher degrees of self-reported autistic traits

Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative afterimages. The afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent afterimages. We discuss possible retinal and post-retinal explanations for prolonged afterimages in people with higher levels of autistic traits

Encoding of Naturalistic Stimuli by Local Field Potential Spectra in Networks of Excitatory and Inhibitory Neurons

Recordings of local field potentials (LFPs) reveal that the sensory cortex displays rhythmic activity and fluctuations over a wide range of frequencies and amplitudes. Yet, the role of this kind of activity in encoding sensory information remains largely unknown. To understand the rules of translation between the structure of sensory stimuli and the fluctuations of cortical responses, we simulated a sparsely connected network of excitatory and inhibitory neurons modeling a local cortical population, and we determined how the LFPs generated by the network encode information about input stimuli. We first considered simple static and periodic stimuli and then naturalistic input stimuli based on electrophysiological recordings from the thalamus of anesthetized monkeys watching natural movie scenes. We found that the simulated network produced stimulus-related LFP changes that were in striking agreement with the LFPs obtained from the primary visual cortex. Moreover, our results demonstrate that the network encoded static input spike rates into gamma-range oscillations generated by inhibitory–excitatory neural interactions and encoded slow dynamic features of the input into slow LFP fluctuations mediated by stimulus–neural interactions. The model cortical network processed dynamic stimuli with naturalistic temporal structure by using low and high response frequencies as independent communication channels, again in agreement with recent reports from visual cortex responses to naturalistic movies. One potential function of this frequency decomposition into independent information channels operated by the cortical network may be that of enhancing the capacity of the cortical column to encode our complex sensory environment

Analysis for water conflict transformation

This article proposes and fleshes out an analytical method designed to support efforts to transform inequitable and unsustainable transboundary water arrangements. Such ‘transformative analysis’ leverages socio-ecological thinking to critically evaluate the processes that have established and maintain an arrangement, including hydro-diplomacy itself. Transformative analysis facilitates the interpretation of strategies to deflect transformation, identification of destructive forms of cooperation, and strategic classification of opportunities for transformation. The assertions are premised on an understanding of the particularities of water conflict, and followed by a discussion of ways researchers may overcome the challenges inherent in the method