Systematic Analysis of Neural Projections Reveals Clonal Composition of the Drosophila Brain

During development neurons are generated by sequential divisions of neural stem cells, or neuroblasts. In the insect brain progeny of certain stem cells form lineage-specific sets of projections that arborize in distinct brain regions, called clonal units. Though this raises the possibility that the entire neural network in the brain might be organized in a clone-dependent fashion, only a small portion of clones has been identified.

Our study showed that the insect brain is formed by a composition of cell-lineage-dependent modules. Clonal analysis reveals organized architecture even in those neuropils without obvious structural landmarks.

Current Biology, online 28 March 2013
http://dx.doi.org/10.1016/j.cub.2013.03.015

Forgetting in C. elegans Is Accelerated by Neuronal Communication via the TIR-1/JNK-1 Pathway

The control of memory retention is important for proper responses to constantly changing environments, but the regulatory mechanisms underlying forgetting have not been fully elucidated. Our genetic analyses in C. elegans revealed that mutants of the TIR-1/JNK-1 pathway exhibited prolonged retention of olfactory adaptation and salt chemotaxis learning. In olfactory adaptation, conditioning induces attenuation of odor-evoked Ca2+ responses in olfactory neurons, and this attenuation is prolonged in the TIR-1/JNK-1-pathway mutant animals. We also found that a pair of neurons in which the pathway functions is required for the acceleration of forgetting, but not for sensation or adaptation, in wild-type animals. In addition, the neurosecretion from these cells is important for the acceleration of forgetting. Therefore, we propose that these neurons accelerate forgetting through the TIR-1/JNK-1 pathway by sending signals that directly or indirectly stimulate forgetting.

Akitoshi Inoue, et al

Cell Reports, Volume 3, Issue 3, 808-819, 21 March 2013

10.1016/j.celrep.2013.02.019

Epigenetic mechanisms in the development and maintenance of dopaminergic neurons

Mesodiencephalic dopaminergic (mdDA) neurons are located in the ventral mesodiencephalon and are involved in psychiatric disorders and severely affected in neurodegenerative diseases such as Parkinson’s disease. mdDA neuronal development has received much attention in the last 15 years and many transcription factors involved in mdDA specification have been discovered. More recently however, the impact of epigenetic regulation has come into focus, and it’s emerging that the processes of histone modification and DNA methylation form the basis of genetic switches that operate during mdDA development. Here, we review the epigenetic control of mdDA development, maturation and maintenance. As we highlight, epigenetic mechanisms play a pivotal role in all of these processes and the knowledge gathered from studying epigenetics in these contexts may aid our understanding of mdDA-related pathologies.

Hendrikus J. van Heesbeen, et al
Development140, 1159-1169.   March 15, 2013
doi:10.1242/dev.089359  

Developmental processes in face perception

Understanding the developmental origins of face recognition has been the goal of many studies of various approaches. Contributions of experience-expectant mechanisms (early component), like perceptual narrowing, and lifetime experience (late component) to face processing remain elusive. By investigating captive chimpanzees of varying age, a rare case of a species with lifelong exposure to non-conspecific faces at distinctive levels of experience, we can disentangle developmental components in face recognition. We found an advantage in discriminating chimpanzee above human faces in young chimpanzees, reflecting a predominant contribution of an early component that drives the perceptual system towards the conspecific morphology, and an advantage for human above chimpanzee faces in old chimpanzees, reflecting a predominant late component that shapes the perceptual system along the critical dimensions of the face exposed to. We simulate the contribution of early and late components using computational modeling and mathematically describe the underlying functions.

Christoph D. Dahl, et al.

Scientific Reports 3, Article number: 1044 doi:10.1038/srep01044

Published 09 January 2013

DNA and Quantum Dots: All That Glitters Is Not Gold

A team of researchers at the National Institute of Standards and Technology (NIST) has shown that by bringing gold nanoparticles close to the dots and using a DNA template to control the distances, the intensity of a quantum dot's fluorescence can be predictably increased or decreased. This breakthrough opens a potential path to using quantum dots as a component in better photodetectors, chemical sensors and nanoscale lasers.

Science Daily, Jan. 25, 2013

Seung Hyeon Ko, Kan Du, J. Alexander Liddle.

Quantum-Dot Fluorescence Lifetime Engineering with DNA Origami Constructs. 

Angewandte Chemie International Edition, 2013; 52 (4): 1193 DOI:10.1002/anie.201206253

Scientists Discover How Epigenetic Information Could Be Inherited: Mechanism of Epigenetic Reprogramming Revealed

New research reveals a potential way for how parents' experiences could be passed to their offspring's genes. The research was published January, 25 in the journal Science.
Science Daily, Jan 25, 2013

Mouse primordial germ cells (PGCs) undergo sequential epigenetic changes and genome-wide DNA demethylation to reset the epigenome for totipotency. Here, the authors demonstrate that erasure of CpG methylation (5mC) in PGCs occurs via conversion to 5-hydroxymethylcytosine (5hmC), driven by high levels of TET1 and TET2. Global conversion to 5hmC initiates asynchronously among PGCs at embryonic day (E) 9.5 to E10.5 and accounts for the unique process of imprint erasure. Mechanistically, 5hmC enrichment is followed by its protracted decline thereafter at a rate consistent with replication-coupled dilution. The conversion to 5hmC is an important component of parallel redundant systems that drive comprehensive reprogramming in PGCs. Nonetheless, they identify rare regulatory elements that escape systematic DNA demethylation in PGCs, providing a potential mechanistic basis for transgenerational epigenetic inheritance.

Jamie A. Hackett, et al.Science 25 January 2013:
Vol. 339 no. 6118 pp. 448-452
DOI: 10.1126/science.12292

Action Plan: Making Brain-Controlled Prosthetics That Can Open a Clothespin

Brain-controlled interfaces have advanced dramatically during the past decade. But more work needs to be done before this technology begins to approximate the natural movements of a fully functioning arm or hand. An attempt to replicate the full range of movement—and the cognitive chain of events from thought to action—has now begun as a research collaboration among the California Institute of Technology, Johns Hopkins University Applied Physics Laboratory, the University of Southern California and Rancho Los Amigos National Rehabilitation Center. These institutions are seeking a few recruits to be fitted with a $500,000 robotic limb.

By Gary Stix,  January 23, 2013, Scientific American

Billion-euro brain simulation and graphene projects win European funds

The European Commission has selected the two research proposals it will fund to the tune of half-a-billion euros each after a two-year, high-profile contest. The Human Brain Project, led by neuroscientist Henry Markram at the Swiss Federal Institute of Technology (EPFL) in Lausanne, plans to simulate everything known about the human brain in a supercomputer — a breathtaking ambition that has been met with some scepticism (See “Brain in a box”).

NATURE | BREAKING NEWS, 23 January 2013
Nature 482, 456–458 (23 February 2012) doi:10.1038/482456a

Synthetic double-helix faithfully stores Shakespeare's sonnets

A team of scientists has produced a truly concise anthology of verse by encoding all 154 of Shakespeare’s sonnets in DNA. The researchers say that their technique could easily be scaled up to store all of the data in the world. Along with the sonnets, the team encoded a 26-second audio clip from Martin Luther King’s famous “I have a dream" speech, a copy of James Watson and Francis Crick’s classic paper on the structure of DNA, a photo of the researchers' institute and a file that describes how the data were converted. The researchers report their results today on Nature’s website.
DNA packs information into much less space than other media. For example, CERN, the European particle-physics lab near Geneva, currently stores around 90 petabytes of data on some 100 tape drives. Goldman’s method could fit all of those data into 41 grams of DNA.
Nature News, 23 January 2013

Towards practical, high-capacity, low-maintenance information storage in synthesized DNAGoldman, N. et al. Nature http://dx.doi.org/10.1038/nature11875 (2013).

Grid cells require excitatory drive from the hippocampus

To determine how hippocampal backprojections influence spatially periodic firing in grid cells, the author recorded neural activity in the medial entorhinal cortex (MEC) of rats after temporary inactivation of the hippocampus. They report two major changes in entorhinal grid cells. First, hippocampal inactivation gradually and selectively extinguished the grid pattern. Second, the same grid cells that lost their grid fields acquired substantial tuning to the direction of the rat's head. This transition in firing properties was contingent on a drop in the average firing rate of the grid cells and could be replicated by the removal of an external excitatory drive in an attractor network model in which grid structure emerges by velocity-dependent translation of activity across a network with inhibitory connections. These results point to excitatory drive from the hippocampus, and possibly other regions, as one prerequisite for the formation and translocation of grid patterns in the MEC.

Tora Bonnevie, et al.
Nature Neuroscience (2013) doi:10.1038/nn.3311, Published online 20 January 2013