From Retinal Waves to Activity-Dependent Retinogeniculate Map Development

A neural model is described of how spontaneous retinal waves are formed in infant mammals, and how these waves organize activity-dependent development of a topographic map in the lateral geniculate nucleus, with connections from each eye segregated into separate anatomical layers. The model simulates the spontaneous behavior of starburst amacrine cells and retinal ganglion cells during the production of retinal waves during the first few weeks of mammalian postnatal development. It proposes how excitatory and inhibitory mechanisms within individual cells, such as Ca2+-activated K+ channels, and cAMP currents and signaling cascades, can modulate the spatiotemporal dynamics of waves, notably by controlling the after-hyperpolarization currents of starburst amacrine cells. Given the critical role of the geniculate map in the development of visual cortex, these results provide a foundation for analyzing the temporal dynamics whereby the visual cortex itself develops

Multifunctional biophotonic nanostructures inspired by the longtail glasswing butterfly for medical devices

Numerous living organisms possess biophotonic nanostructures that provide colouration and other diverse functions for survival. While such structures have been actively studied and replicated in the laboratory, it remains unclear whether they can be used for biomedical applications. Here, we show a transparent photonic nanostructure inspired by the longtail glasswing butterfly (Chorinea faunus) and demonstrate its use in intraocular pressure (IOP) sensors in vivo. We exploit the phase separation between two immiscible polymers (poly(methyl methacrylate) and polystyrene) to form nanostructured features on top of a Si3_N_4 substrate. The membrane thus formed shows good angle-independent white-light transmission, strong hydrophilicity and anti-biofouling properties, which prevent adhesion of proteins, bacteria and eukaryotic cells. We then developed a microscale implantable IOP sensor using our photonic membrane as an optomechanical sensing element. Finally, we performed in vivo testing on New Zealand white rabbits, which showed that our device reduces the mean IOP measurement variation compared with conventional rebound tonometry without signs of inflammation

Transient Neuronal Populations Are Required to Guide Callosal Axons: A Role for Semaphorin 3C

Neurons, glia, and callosal axons operate as a “ménage à trois” in the development of the corpus callosum

Regulation of axon regeneration by the RNA repair and splicing pathway

Mechanisms governing a neuron's regenerative ability are important but not well understood. We identify Rtca (RNA 3′-terminal phosphate cyclase) as an inhibitor of axon regeneration. Removal of Rtca cell-autonomously enhanced axon regrowth in the Drosophila CNS, whereas its overexpression reduced axon regeneration in the periphery. Rtca along with the RNA ligase Rtcb and its catalyst Archease operate in the RNA repair and splicing pathway important for stress-induced mRNA splicing, including that of Xbp1, a cellular stress sensor. Drosophila Rtca and Archease had opposing effects on Xbp1 splicing, and deficiency of Archease or Xbp1 impeded axon regeneration in Drosophila. Moreover, overexpressing mammalian Rtca in cultured rodent neurons reduced axonal complexity in vitro, whereas reducing its function promoted retinal ganglion cell axon regeneration after optic nerve crush in mice. Our study thus links axon regeneration to cellular stress and RNA metabolism, revealing new potential therapeutic targets for treating nervous system trauma

Regulation of axon regeneration by the RNA repair and splicing pathway

© 2015 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. Mechanisms governing a neuron's regenerative ability are important but not well understood. We identify Rtca (RNA 3′-terminal phosphate cyclase) as an inhibit