@article{9143, abstract = {Understanding and predicting the response of the hydrological cycle to climate change is a major challenge with important societal implications. Much progress has been made in understanding the response of global average precipitation by considering the energy balances of the atmosphere and the surface1,2,3,4,5,6. This energetic perspective reveals that changes in temperature, greenhouse gases, aerosols, solar forcing and cloud feedbacks can all affect the global average rate of precipitation5,7,8,9,10,11. Local precipitation changes have conventionally been analysed using the water vapour budget, but here we show that the energetic approach can be extended to local changes in precipitation by including changes in horizontal energy transport. In simulations of twenty-first century climate change, this energy transport accounts for much of the spatial variability in precipitation change. We show that changes in radiative and surface sensible heat fluxes are a guide to the local precipitation response over land and at large scales, but not at small scales over the ocean, where cloud and water vapour radiative feedbacks dampen the response. The energetic approach described here helps bridge the gap between our understanding of global and regional precipitation changes. It could be applied to better understand the response of regional precipitation to different radiative forcings, including geo-engineering schemes, as well as to understand the differences between the fast and slow responses of regional precipitation to such forcings.}, author = {Muller, Caroline J and O’Gorman, P. A.}, issn = {1758-678X}, journal = {Nature Climate Change}, number = {5}, pages = {266--271}, publisher = {Springer Nature}, title = {{An energetic perspective on the regional response of precipitation to climate change}}, doi = {10.1038/nclimate1169}, volume = {1}, year = {2011}, } @article{9144, abstract = {A cloud-resolving model is used to investigate the effect of warming on high percentiles of precipitation (precipitation extremes) in the idealized setting of radiative-convective equilibrium. While this idealized setting does not allow for several factors that influence precipitation in the tropics, it does allow for an evaluation of the response of precipitation extremes to warming in simulations with resolved rather than parameterized convection. The methodology developed should also be applicable to less idealized simulations. Modeled precipitation extremes are found to increase in magnitude in response to an increase in sea surface temperature. A dry static energy budget is used to relate the changes in precipitation extremes to changes in atmospheric temperature, vertical velocity, and precipitation efficiency. To first order, the changes in precipitation extremes are captured by changes in the mean temperature structure of the atmosphere. Changes in vertical velocities play a secondary role and tend to weaken the strength of precipitation extremes, despite an intensification of updraft velocities in the upper troposphere. The influence of changes in condensate transports on precipitation extremes is quantified in terms of a precipitation efficiency; it does not change greatly with warming. Tropical precipitation extremes have previously been found to increase at a greater fractional rate than the amount of atmospheric water vapor in observations of present-day variability and in some climate model simulations with parameterized convection. But the fractional increases in precipitation extremes in the cloud-resolving simulations are comparable in magnitude to those in surface water vapor concentrations (owing to a partial cancellation between dynamical and thermodynamical changes), and are substantially less than the fractional increases in column water vapor.}, author = {Muller, Caroline J and O’Gorman, Paul A. and Back, Larissa E.}, issn = {1520-0442}, journal = {Journal of Climate}, keywords = {Atmospheric Science}, number = {11}, pages = {2784--2800}, publisher = {American Meteorological Society}, title = {{Intensification of precipitation extremes with warming in a cloud-resolving model}}, doi = {10.1175/2011jcli3876.1}, volume = {24}, year = {2011}, } @article{918, abstract = {We study theoretically the shapes of a dividing epithelial monolayer of cells lying on top of an elastic stroma. The negative tension created by cell division provokes a buckling instability at a finite wave vector leading to the formation of periodic arrays of villi and crypts. The instability is similar to the buckling of a metallic plate under compression. We use the results to rationalize the various structures of the intestinal lining observed in vivo. Taking into account the coupling between cell division and local curvature, we obtain different patterns of villi and crypts, which could explain the different morphologies of the small intestine and the colon.}, author = {Hannezo, Edouard B and Prost, Jacques and Joanny, Jean}, journal = {Physical Review Letters}, number = {7}, publisher = {American Physical Society}, title = {{Instabilities of monolayered epithelia Shape and structure of villi and crypts}}, doi = {10.1103/PhysRevLett.107.078104}, volume = {107}, year = {2011}, } @article{919, abstract = {Collective cell migration in tissues occurs throughout embryonic development, during wound healing, and in cancerous tumor invasion, yet most detailed knowledge of cell migration comes from single-cell studies. As single cells migrate, the shape of the cell body fluctuates dramatically through cyclic processes of extension, adhesion, and retraction, accompanied by erratic changes in migration direction. Within confluent cell layers, such subcellular motions must be coupled between neighbors, yet the influence of these subcellular motions on collective migration is not known. Here we study motion within a confluent epithelial cell sheet, simultaneously measuring collective migration and subcellular motions, covering a broad range of length scales, time scales, and cell densities. At large length scales and time scales collective migration slows as cell density rises, yet the fastest cells move in large, multicell groups whose scale grows with increasing cell density. This behavior has an intriguing analogy to dynamic heterogeneities found in particulate systems as they become more crowded and approach a glass transition. In addition we find a diminishing self-diffusivity of short-wavelength motions within the cell layer, and growing peaks in the vibrational density of states associated with cooperative cell-shape fluctuations. Both of these observations are also intriguingly reminiscent of a glass transition. Thus, these results provide a broad and suggestive analogy between cell motion within a confluent layer and the dynamics of supercooled colloidal and molecular fluids approaching a glass transition.}, author = {Angelini, Thomas and Hannezo, Edouard B and Trepatc, Xavier and Marquez, Manuel and Fredberg, Jeffrey and Weitz, David}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {12}, pages = {4714 -- 4719}, publisher = {PNAS}, title = {{Glass-like dynamics of collective cell migration}}, doi = {10.1073/pnas.1010059108}, volume = {108}, year = {2011}, } @article{923, abstract = {The conserved role of Notch signaling in controlling intestinal cell fate specification and homeostasis has been extensively studied. Nevertheless, the precise identity of the cells in which Notch signaling is active and the role of different Notch receptor paralogues in the intestine remain ambiguous, due to the lack of reliable tools to investigate Notch expression and function in vivo. We generated a new series of transgenic mice that allowed us, by lineage analysis, to formally prove that Notch1 and Notch2 are specifically expressed in crypt stem cells. In addition, a novel Notch reporter mouse, Hes1-EmGFP SAT, demonstrated exclusive Notch activity in crypt stem cells and absorptive progenitors. This roster of knock-in and reporter mice represents a valuable resource to functionally explore the Notch pathway in vivo in virtually all tissues.}, author = {Fré, Silvia and Hannezo, Edouard B and Šale, Sanja and Huyghe, Mathilde and Lafkas, Daniel and Kissel, Holger and Louvi, Angeliki and Greve, Jeffrey and Louvard, Daniel and Artavanis Tsakonas, Spyros}, journal = {PLoS One}, number = {10}, publisher = {Public Library of Science}, title = {{Notch lineages and activity in intestinal stem cells determined by a new set of knock in mice}}, doi = {10.1371/journal.pone.0025785}, volume = {6}, year = {2011}, } @article{7076, abstract = {Iron is a ubiquitous impurity in metamict (radiation-damaged and partially amorphized) materials such as titanite (CaSiTiO5). Using 57Fe Mössbauer spectroscopy we find that iron in metamict titanite is partitioned between amorphous and crystalline regions based on valence. Trivalent iron exists in the crystalline titanite matrix whereas divalent iron exists almost exclusively in radiation-amorphized regions. We find that the relative abundances of the oxidation states correlate with the volume fraction of amorphous and crystalline regions. Our data also show that oxidation of iron proceeds along with the recrystallization of the amorphized regions. Recrystallization is confirmed to occur over the range 700 °C < T < 925 °C, and no further structural changes are observed at higher temperatures. It is surprising that our Mössbauer measurements show divalent iron to be surrounded by titanite with a high degree of short-range structural order in the amorphized regions. This observation is fundamentally different from other metamict materials such as zircon (ZrSiO4), where amorphized regions show no short-range order.}, author = {Salje, E K H and Safarik, D J and Taylor, R D and Pasternak, M P and Modic, Kimberly A and Groat, L A and Lashley, J C}, issn = {0953-8984}, journal = {Journal of Physics: Condensed Matter}, number = {10}, publisher = {IOP Publishing}, title = {{Determination of iron sites and the amount of amorphization in radiation-damaged titanite (CaSiTiO5)}}, doi = {10.1088/0953-8984/23/10/105402}, volume = {23}, year = {2011}, } @article{7077, abstract = {Pb, Te, Ag and Se, when reacted in a 1:1:x:1 (x = 1.9, 2.0, 2.01) molar ratio, form a two phase composite which consists of a phase which crystallizes in the fcc cubic PbSe structure and a phase that crystallizes in the Ag2Te structure. In this article, we demonstrate that by varying the Ag concentration, we can manipulate which variant of the Ag2Te structure stabilizes at room temperature (monoclinic α-Ag2Te or cubic β-Ag1.9Te) and can consequently manipulate the electrical and thermal transport behavior of the composite and hence the thermoelectric performance. Additionally, we show that Cu-doping results in an overall improvement in thermoelectric performance. Our results suggest that formation of composites is a viable path for achieving a phonon-glass-electron-crystal (PGEC) alloy.}, author = {Capps, J. and Ma, B. and Drye, T. and Nucklos, C. and Lindsey, S. and Rhodes, D. and Zhang, Q. and Modic, Kimberly A and Cawthorne, S. and Drymiotis, F.}, issn = {0925-8388}, journal = {Journal of Alloys and Compounds}, number = {5}, pages = {1544--1549}, publisher = {Elsevier}, title = {{The effect of Ag concentration on the structural, electrical and thermal transport behavior of Pb:Te:Ag:Se mixtures and improvement of thermoelectric performance via Cu doping}}, doi = {10.1016/j.jallcom.2010.10.187}, volume = {509}, year = {2011}, } @article{7313, abstract = {Li-ion batteries have transformed portable electronics and will play a key role in the electrification of transport. However, the highest energy storage possible for Li-ion batteries is insufficient for the long-term needs of society, for example, extended-range electric vehicles. To go beyond the horizon of Li-ion batteries is a formidable challenge; there are few options. Here we consider two: Li–air (O2) and Li–S. The energy that can be stored in Li–air (based on aqueous or non-aqueous electrolytes) and Li–S cells is compared with Li-ion; the operation of the cells is discussed, as are the significant hurdles that will have to be overcome if such batteries are to succeed. Fundamental scientific advances in understanding the reactions occurring in the cells as well as new materials are key to overcoming these obstacles. The potential benefits of Li–air and Li–S justify the continued research effort that will be needed.}, author = {Bruce, Peter G. and Freunberger, Stefan Alexander and Hardwick, Laurence J. and Tarascon, Jean-Marie}, issn = {1476-1122}, journal = {Nature Materials}, number = {1}, pages = {19--29}, publisher = {Springer Nature}, title = {{Li–O2 and Li–S batteries with high energy storage}}, doi = {10.1038/nmat3191}, volume = {11}, year = {2011}, } @article{7314, abstract = {The electrolyte is one of the greatest challenges facing the development of the non‐aqueous Li–O2 battery. Although ether‐based electrolytes do from Li2O2 on the first discharge, it is shown by various techniques that they also decompose and that decomposition increases while Li2O2 decreases on cycling (see picture). Thus, these electrolytes are not suitable. }, author = {Freunberger, Stefan Alexander and Chen, Yuhui and Drewett, Nicholas E. and Hardwick, Laurence J. and Bardé, Fanny and Bruce, Peter G.}, issn = {1433-7851}, journal = {Angewandte Chemie International Edition}, number = {37}, pages = {8609--8613}, publisher = {Wiley}, title = {{The Lithium-Oxygen battery with ether-based electrolytes}}, doi = {10.1002/anie.201102357}, volume = {50}, year = {2011}, } @article{7315, abstract = {Spectroscopic data (see picture) provide direct evidence that in non‐aqueous Li+ electrolyte, O2 is reduced to O2−, which then forms LiO2 on the electrode surface which disproportionates to Li2O2. On charging, Li2O2 decomposes directly, in a one‐step reaction to evolve O2 and does not pass through LiO2 as an intermediate. }, author = {Peng, Zhangquan and Freunberger, Stefan Alexander and Hardwick, Laurence J. and Chen, Yuhui and Giordani, Vincent and Bardé, Fanny and Novák, Petr and Graham, Duncan and Tarascon, Jean-Marie and Bruce, Peter G.}, issn = {1433-7851}, journal = {Angewandte Chemie International Edition}, number = {28}, pages = {6351--6355}, publisher = {Wiley}, title = {{Oxygen reactions in a non-aqueous Li+ electrolyte}}, doi = {10.1002/anie.201100879}, volume = {50}, year = {2011}, } @article{7316, abstract = {The nonaqueous rechargeable lithium–O2 battery containing an alkyl carbonate electrolyte discharges by formation of C3H6(OCO2Li)2, Li2CO3, HCO2Li, CH3CO2Li, CO2, and H2O at the cathode, due to electrolyte decomposition. Charging involves oxidation of C3H6(OCO2Li)2, Li2CO3, HCO2Li, CH3CO2Li accompanied by CO2 and H2O evolution. Mechanisms are proposed for the reactions on discharge and charge. The different pathways for discharge and charge are consistent with the widely observed voltage gap in Li–O2 cells. Oxidation of C3H6(OCO2Li)2 involves terminal carbonate groups leaving behind the OC3H6O moiety that reacts to form a thick gel on the Li anode. Li2CO3, HCO2Li, CH3CO2Li, and C3H6(OCO2Li)2 accumulate in the cathode on cycling correlating with capacity fading and cell failure. The latter is compounded by continuous consumption of the electrolyte on each discharge.}, author = {Freunberger, Stefan Alexander and Chen, Yuhui and Peng, Zhangquan and Griffin, John M. and Hardwick, Laurence J. and Bardé, Fanny and Novák, Petr and Bruce, Peter G.}, issn = {0002-7863}, journal = {Journal of the American Chemical Society}, number = {20}, pages = {8040--8047}, publisher = {ACS}, title = {{Reactions in the rechargeable Lithium–O2 battery with alkyl carbonate electrolytes}}, doi = {10.1021/ja2021747}, volume = {133}, year = {2011}, } @article{7317, abstract = {Lithium-metal oxides with a high formal Li2O content, such as Li5FeO4 (5Li2O•Fe2O3) and a Li2MnO3•LiFeO2 composite ({Li2O•MnO2}•{Li2O•Fe2O3}) have been explored as electrocatalysts for primary and rechargeable Li-O2 cells. Activation occurs predominantly by Li2O removal, either electrochemically or chemically by acid-treatment. Superior electrochemical behavior is obtained if activation occurs by acid-treatment; Li2MnO3•LiFeO2 catalysts provide 2516 mAh/g (carbon) corresponding to 931 mAh/g (electrocatalyst + carbon) during the initial discharge. The reaction is reasonably reversible during the early cycles. The approach has implications for designing electrocatalysts that participate through electrochemical Li2O extraction/reformation reactions, offering exceptionally high capacities.}, author = {Trahey, L. and Johnson, C. S. and Vaughey, J. T. and Kang, S.-H. and Hardwick, L. J. and Freunberger, Stefan Alexander and Bruce, P. G. and Thackeray, M. M.}, issn = {1099-0062}, journal = {Electrochemical and Solid-State Letters}, number = {5}, publisher = {The Electrochemical Society}, title = {{Activated Lithium-Metal-Oxides as catalytic electrodes for Li–O2 cells}}, doi = {10.1149/1.3555366}, volume = {14}, year = {2011}, } @inproceedings{757, abstract = {Synchronous distributed algorithms are easier to design and prove correct than algorithms that tolerate asynchrony. Yet, in the real world, networks experience asynchrony and other timing anomalies. In this paper, we address the question of how to efficiently transform an algorithm that relies on synchronization into an algorithm that tolerates asynchronous executions. We introduce a transformation technique from synchronous algorithms to indulgent algorithms [1], which induces only a constant overhead in terms of time complexity in well-behaved executions. Our technique is based on a new abstraction we call an asynchrony detector, which the participating processes implement collectively. The resulting transformation works for a large class of colorless tasks, including consensus and set agreement. Interestingly, we also show that our technique is relevant for colored tasks, by applying it to the renaming problem, to obtain the first indulgent renaming algorithm.}, author = {Alistarh, Dan-Adrian and Gilbert, Seth and Guerraoui, Rachid and Travers, Corentin}, pages = {41 -- 52}, publisher = {Springer}, title = {{Generating fast indulgent algorithms}}, doi = {10.1007/978-3-642-17679-1_4}, volume = {6522 LNCS}, year = {2011}, } @inproceedings{759, abstract = {We study the complexity of renaming, a fundamental problem in distributed computing in which a set of processes need to pick distinct names from a given namespace. We prove an individual lower bound of Ω(k) process steps for deterministic renaming into any namespace of size sub-exponential in k, where k is the number of participants. This bound is tight: it draws an exponential separation between deterministic and randomized solutions, and implies new tight bounds for deterministic fetch-and-increment registers, queues and stacks. The proof of the bound is interesting in its own right, for it relies on the first reduction from renaming to another fundamental problem in distributed computing: mutual exclusion. We complement our individual bound with a global lower bound of Ω(k log (k/c)) on the total step complexity of renaming into a namespace of size ck, for any c ≥ 1. This applies to randomized algorithms against a strong adversary, and helps derive new global lower bounds for randomized approximate counter and fetch-and-increment implementations, all tight within logarithmic factors.}, author = {Alistarh, Dan-Adrian and Aspnes, James and Gilbert, Seth and Guerraoui, Rachid}, pages = {718 -- 727}, publisher = {IEEE}, title = {{The complexity of renaming}}, doi = {10.1109/FOCS.2011.66}, year = {2011}, } @inproceedings{760, abstract = {A randomized implementation is given of a test-and-set register with O(log log n) individual step complexity and O(n) total step complexity against an oblivious adversary. The implementation is linearizable and multi-shot, and shows an exponential complexity improvement over previous solutions designed to work against a strong adversary.}, author = {Alistarh, Dan-Adrian and Aspnes, James}, pages = {97 -- 109}, publisher = {Springer}, title = {{Sub-logarithmic test-and-set against a weak adversary}}, doi = {10.1007/978-3-642-24100-0_7}, volume = {6950 LNCS}, year = {2011}, } @inproceedings{761, abstract = {We give two new randomized algorithms for strong renaming, both of which work against an adaptive adversary in asynchronous shared memory. The first uses repeated sampling over a sequence of arrays of decreasing size to assign unique names to each of n processes with step complexity O(log3 n). The second transforms any sorting network into a strong adaptive renaming protocol, with an expected cost equal to the depth of the sorting network. Using an AKS sorting network, this gives a strong adaptive renaming algorithm with step complexity O(log k), where k is the contention in the current execution. We show this to be optimal based on a classic lower bound of Jayanti. We also show that any such strong renaming protocol can be used to build a monotone-consistent counter with logarithmic step complexity (at the cost of adding a max register) or a linearizable fetch-and-increment register (at the cost of increasing the step complexity by a logarithmic factor).}, author = {Alistarh, Dan-Adrian and Aspnes, James and Censor Hillel, Keren and Gilbert, Seth and Zadimoghaddam, Morteza}, pages = {239 -- 248}, publisher = {ACM}, title = {{Optimal-time adaptive strong renaming, with applications to counting}}, doi = {10.1145/1993806.1993850}, year = {2011}, } @article{7701, abstract = {During assembly of the Drosophila olfactory circuit, projection neuron (PN) dendrites prepattern the developing antennal lobe before the arrival of axons from their presynaptic partners, the adult olfactory receptor neurons (ORNs). We previously found that levels of transmembrane Semaphorin-1a, which acts as a receptor, instruct PN dendrite targeting along the dorsolateral-ventromedial axis. Here we show that two secreted semaphorins, Sema-2a and Sema-2b, provide spatial cues for PN dendrite targeting. Sema-2a and Sema-2b proteins are distributed in gradients opposing the Sema-1a protein gradient, and Sema-1a binds to Sema-2a-expressing cells. In Sema-2a and Sema-2b double mutants, PN dendrites that normally target dorsolaterally in the antennal lobe mistarget ventromedially, phenocopying cell-autonomous Sema-1a removal from these PNs. Cell ablation, cell-specific knockdown, and rescue experiments indicate that secreted semaphorins from degenerating larval ORN axons direct dendrite targeting. Thus, a degenerating brain structure instructs the wiring of a developing circuit through the repulsive action of secreted semaphorins.}, author = {Sweeney, Lora Beatrice Jaeger and Chou, Ya-Hui and Wu, Zhuhao and Joo, William and Komiyama, Takaki and Potter, Christopher J. and Kolodkin, Alex L. and Garcia, K. Christopher and Luo, Liqun}, issn = {0896-6273}, journal = {Neuron}, number = {5}, pages = {734--747}, publisher = {Elsevier}, title = {{Secreted semaphorins from degenerating larval ORN axons direct adult projection neuron dendrite targeting}}, doi = {10.1016/j.neuron.2011.09.026}, volume = {72}, year = {2011}, } @article{7702, abstract = {Longitudinal axon fascicles within the Drosophila embryonic CNS provide connections between body segments and are required for coordinated neural signaling along the anterior-posterior axis. We show here that establishment of select CNS longitudinal tracts and formation of precise mechanosensory afferent innervation to the same CNS region are coordinately regulated by the secreted semaphorins Sema-2a and Sema-2b. Both Sema-2a and Sema-2b utilize the same neuronal receptor, plexin B (PlexB), but serve distinct guidance functions. Localized Sema-2b attraction promotes the initial assembly of a subset of CNS longitudinal projections and subsequent targeting of chordotonal sensory afferent axons to these same longitudinal connectives, whereas broader Sema-2a repulsion serves to prevent aberrant innervation. In the absence of Sema-2b or PlexB, chordotonal afferent connectivity within the CNS is severely disrupted, resulting in specific larval behavioral deficits. These results reveal that distinct semaphorin-mediated guidance functions converge at PlexB and are critical for functional neural circuit assembly.}, author = {Wu, Zhuhao and Sweeney, Lora Beatrice Jaeger and Ayoob, Joseph C. and Chak, Kayam and Andreone, Benjamin J. and Ohyama, Tomoko and Kerr, Rex and Luo, Liqun and Zlatic, Marta and Kolodkin, Alex L.}, issn = {0896-6273}, journal = {Neuron}, number = {2}, pages = {281--298}, publisher = {Elsevier}, title = {{A combinatorial semaphorin code instructs the initial steps of sensory circuit assembly in the Drosophila CNS}}, doi = {10.1016/j.neuron.2011.02.050}, volume = {70}, year = {2011}, } @article{7750, author = {Robinson, Matthew Richard}, issn = {1465-7279}, journal = {Behavioral Ecology}, number = {6}, pages = {1143--1144}, publisher = {Oxford University Press}, title = {{Understanding intrasexual competition and sexual selection requires an evolutionary ecology framework}}, doi = {10.1093/beheco/arr110}, volume = {22}, year = {2011}, } @article{8025, abstract = {Chandelier (axoaxonic) cells (ChCs) are a distinct group of GABAergic interneurons that innervate the axon initial segments of pyramidal cells. However, their circuit role and the function of their clearly defined anatomical specificity remain unclear. Recent work has demonstrated that chandelier cells can produce depolarizing GABAergic PSPs, occasionally driving postsynaptic targets to spike. On the other hand, other work suggests that ChCs are hyperpolarizing and may have an inhibitory role. These disparate functional effects may reflect heterogeneity among ChCs. Here, using brain slices from transgenic mouse strains, we first demonstrate that, across different neocortical areas and genetic backgrounds, upper Layer 2/3 ChCs belong to a single electrophysiologically and morphologically defined population, extensively sampling Layer 1 inputs with asymmetric dendrites. Consistent with being a single cell type, we find electrical coupling between ChCs. We then investigate the effect of chandelier cell activation on pyramidal neuron spiking in several conditions, ranging from the resting membrane potential to stimuli designed to approximate in vivo membrane potential dynamics. We find that under quiescent conditions, chandelier cells are capable of both promoting and inhibiting spike generation, depending on the postsynaptic membrane potential. However, during in vivo-like membrane potential fluctuations, the dominant postsynaptic effect was a strong inhibition. Thus, neocortical chandelier cells, even from within a homogeneous population, appear to play a dual role in the circuit, helping to activate quiescent pyramidal neurons, while at the same time inhibiting active ones.}, author = {Woodruff, A. R. and McGarry, L. M. and Vogels, Tim P and Inan, M. and Anderson, S. A. and Yuste, R.}, issn = {0270-6474}, journal = {Journal of Neuroscience}, number = {49}, pages = {17872--17886}, publisher = {Society for Neuroscience}, title = {{State-dependent function of neocortical chandelier cells}}, doi = {10.1523/jneurosci.3894-11.2011}, volume = {31}, year = {2011}, }