http://www.neuralsystemsandcircuits.com The most accessed research articles published by Neural Systems & Circuits 2012-01-30T00:00:00Z The development of neuroscience over the last 50 years has some similarities with the development of physics in the 17th Century. Towards the beginning of that century Bacon promoted the systematic gathering of experimental data and the induction of scientific truth; towards the end Newton expressed his principles of gravitation and motion in a concise set of mathematical equations that made precise falsifiable predictions. This paper expresses the opinion that as neuroscience comes of age it needs to move away from amassing large quantities of data about the brain, and adopt a Popperian model in which theories are developed that can make strong falsifiable predictions and guide future experimental work. http://www.neuralsystemsandcircuits.com/content/2/1/2 David Gamez Neural Systems & Circuits 2012, null:2 2012-01-30T00:00:00Z doi:10.1186/2042-1001-2-2 /content/figures/2042-1001-2-2-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 2 2012-01-30T00:00:00Z PDF - http://www.neuralsystemsandcircuits.com/content/1/1/14 Anna Webb Peter Latham Venkatesh Murthy Neural Systems & Circuits 2011, null:14 2011-10-06T00:00:00Z doi:10.1186/2042-1001-1-14 /content/figures/2042-1001-1-14-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 14 2011-10-06T00:00:00Z XML The olfactory bulb (OB) receives and integrates newborn interneurons throughout life. This process is important for the proper functioning of the OB circuit and consequently, for the sense of smell. Although we know how these new interneurons are produced, the way in which they integrate into the pre-existing ongoing circuits remains poorly documented. Bearing in mind that glutamatergic inputs onto local OB interneurons are crucial for adjusting the level of bulbar inhibition, it is important to characterize when and how these inputs from excitatory synapses develop on newborn OB interneurons. We studied early synaptic events that lead to the formation and maturation of the first glutamatergic synapses on adult-born granule cells (GCs), the most abundant subtype of OB interneuron. Patch-clamp recordings and electron microscopy (EM) analysis were performed on adult-born interneurons shortly after their arrival in the adult OB circuits. We found that both the ratio of N-methyl-D-aspartate receptor (NMDAR) to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), and the number of functional release sites at proximal inputs reached a maximum during the critical period for the sensory-dependent survival of newborn cells, well before the completion of dendritic arborization. EM analysis showed an accompanying change in postsynaptic density shape during the same period of time. Interestingly, the latter morphological changes disappeared in more mature newly-formed neurons, when the NMDAR to AMPAR ratio had decreased and functional presynaptic terminals expressed only single release sites. Together, these findings show that the first glutamatergic inputs to adult-generated OB interneurons undergo a unique sequence of maturation stages. http://www.neuralsystemsandcircuits.com/content/1/1/6 Hiroyuki Katagiri Marta Pallotto Antoine Nissant Kerren Murray Marco Sassoe-Pognetto Pierre-Marie Lledo Neural Systems & Circuits 2011, null:6 2011-02-01T00:00:00Z doi:10.1186/2042-1001-1-6 /content/figures/2042-1001-1-6-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 6 2011-02-01T00:00:00Z XML The 8th annual Computational and Systems Neuroscience meeting (Cosyne) was held February 24-27, 2011 in Salt Lake City, Utah (abstracts are freely available online: http://www.cosyne.org/c/index.php?title=Cosyne2011_Program). Cosyne brings together experimental and theoretical approaches to systems neuroscience, with the goal of understanding neurons, neural assemblies, and the perceptual, cognitive and behavioral functions they mediate. http://www.neuralsystemsandcircuits.com/content/1/1/8 Mark Histed Jonathan Pillow Neural Systems & Circuits 2011, null:8 2011-04-20T00:00:00Z doi:10.1186/2042-1001-1-8 /content/figures/2042-1001-1-8-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 8 2011-04-20T00:00:00Z XML The environment has a central role in shaping developmental trajectories and determining the phenotype so that animals are adapted to the specific conditions they encounter. Epigenetic mechanisms can have many effects, with changes in the nervous and musculoskeletal systems occurring at different rates. How is the function of an animal maintained whilst these transitions happen? Phenotypic plasticity can change the ways in which animals respond to the environment and even how they sense it, particularly in the context of social interactions between members of their own species. In the present article, we review the mechanisms and consequences of phenotypic plasticity by drawing upon the desert locust as an unparalleled model system. Locusts change reversibly between solitarious and gregarious phases that differ dramatically in appearance, general physiology, brain function and structure, and behaviour. Solitarious locusts actively avoid contact with other locusts, but gregarious locusts may live in vast, migrating swarms dominated by competition for scarce resources and interactions with other locusts. Different phase traits change at different rates: some behaviours take just a few hours, colouration takes a lifetime and the muscles and skeleton take several generations. The behavioural demands of group living are reflected in gregarious locusts having substantially larger brains with increased space devoted to higher processing. Phase differences are also apparent in the functioning of identified neurons and circuits. The whole transformation process of phase change pivots on the initial and rapid behavioural decision of whether or not to join with other locusts. The resulting positive feedback loops from the presence or absence of other locusts drives the process to completion. Phase change is accompanied by dramatic changes in neurochemistry, but only serotonin shows a substantial increase during the critical one- to four-hour window during which gregarious behaviour is established. Blocking the action of serotonin or its synthesis prevents the establishment of gregarious behaviour. Applying serotonin or its agonists promotes the acquisition of gregarious behaviour even in a locust that has never encountered another locust. The analysis of phase change in locusts provides insights into a feedback circuit between the environment and epigenetic mechanisms and more generally into the neurobiology of social interaction. http://www.neuralsystemsandcircuits.com/content/1/1/11 Malcolm Burrows Stephen Rogers Swidbert Ott Neural Systems & Circuits 2011, null:11 2011-07-26T00:00:00Z doi:10.1186/2042-1001-1-11 /content/figures/2042-1001-1-11-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 11 2011-07-26T00:00:00Z XML No description available http://www.neuralsystemsandcircuits.com/content/2/1/1 Peter Latham Venkatesh Murthy Neural Systems & Circuits 2012, null:1 2012-01-05T00:00:00Z doi:10.1186/2042-1001-2-1 /content/figures/2042-1001-2-1-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 1 2012-01-05T00:00:00Z XML Background: The antennal lobe of Drosophila is perhaps one of the best understood neural circuits, because of its well-described anatomical and functional organization and ease of genetic manipulation. Olfactory lobe interneurons - key elements of information processing in this network - are thought to be generated by three identified central brain neuroblasts, all of which generate projection neurons. One of these neuroblasts, located lateral to the antennal lobe, also gives rise to a population of local interneurons, which can either be inhibitory (GABAergic) or excitatory (cholinergic). Recent studies of local interneuron number and diversity suggest that additional populations of this class of neurons exist in the antennal lobe. This implies that other, as yet unidentified, neuroblast lineages may contribute a substantial number of local interneurons to the olfactory circuitry of the antennal lobe. Results: We identified and characterized a novel glutamatergic local interneuron lineage in the Drosophila antennal lobe. We used MARCM (mosaic analysis with a repressible cell marker) and dual-MARCM clonal analysis techniques to identify this novel lineage unambiguously, and to characterize interneurons contained in the lineage in terms of structure, neurotransmitter identity, and development. We demonstrated the glutamatergic nature of these interneurons by immunohistochemistry and use of an enhancer-trap strain, which reports the expression of the Drosophila vesicular glutamate transporter (DVGLUT). We also analyzed the neuroanatomical features of these local interneurons at single-cell resolution, and documented the marked diversity in their antennal lobe glomerular innervation patterns. Finally, we tracked the development of these dLim-1 and Cut positive interneurons during larval and pupal stages. Conclusions: We have identified a novel neuroblast lineage that generates neurons in the antennal lobe of Drosophila. This lineage is remarkably homogeneous in three respects. All of the progeny are local interneurons, which are uniform in their glutamatergic neurotransmitter identity, and form oligoglomerular or multiglomerular innervations within the antennal lobe. The identification of this novel lineage and the elucidation of the innervation patterns of its local interneurons (at single cell resolution) provides a comprehensive cellular framework for emerging studies on the formation and function of potentially excitatory local interactions in the circuitry of the Drosophila antennal lobe. http://www.neuralsystemsandcircuits.com/content/1/1/4 Abhijit Das Albert Chiang Sejal Davla Rashi Priya Heinrich Reichert K VijayRaghavan Veronica Rodrigues Neural Systems & Circuits 2011, null:4 2011-01-26T00:00:00Z doi:10.1186/2042-1001-1-4 /content/figures/2042-1001-1-4-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 4 2011-01-26T00:00:00Z XML Background: Mitral and tufted cells are the projection neurons in the olfactory bulb, conveying odour information to various regions of the olfactory cortex. In spite of their functional importance, there are few molecular and genetic tools that can be used for selective labelling or manipulation of mitral and tufted cells. Tbx21 was first identified as a T-box family transcription factor regulating the differentiation and function of T lymphocytes. In the brain, Tbx21 is specifically expressed in mitral and tufted cells of the olfactory bulb. Results: In this study, we performed a promoter/enhancer analysis of mouse Tbx21 gene by comparing nucleotide sequence similarity of Tbx21 genes among several mammalian species and generating transgenic mouse lines with various lengths of 5' upstream region fused to a fluorescent reporter gapVenus. We identified the cis-regulatory enhancer element (~300 nucleotides) at ~ 3.0 kb upstream of the transcription start site of Tbx21 gene, which is both necessary and sufficient for transgene expression in mitral and tufted cells. In contrast, the 2.6-kb 5'-flanking region of mouse Tbx21 gene induced transgene expression with variable patterns in restricted populations of neurons predominantly located along the olfactory pathway. Furthermore, we generated transgenic mice expressing the genetically-encoded fluorescent exocytosis indicator, synaptopHluorin, in mitral and tufted cells for visualization of presynaptic neural activities in the piriform cortex. Conclusions: The transcriptional enhancer of Tbx21 gene provides a powerful tool for genetic manipulations of mitral and tufted cells in studying the development and function of the secondary olfactory pathways from the bulb to the cortex. http://www.neuralsystemsandcircuits.com/content/1/1/5 Sachiko Mitsui Kei Igarashi Kensaku Mori Yoshihiro Yoshihara Neural Systems & Circuits 2011, null:5 2011-02-01T00:00:00Z doi:10.1186/2042-1001-1-5 /content/figures/2042-1001-1-5-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 5 2011-02-01T00:00:00Z XML Background: Understanding circuit function would be greatly facilitated by methods that allow the simultaneous estimation of the functional strengths of all of the synapses in the network during ongoing network activity. Towards that end, we used Granger causality analysis on electrical recordings from the pyloric network of the crab Cancer borealis, a small rhythmic circuit with known connectivity, and known neuronal intrinsic properties. Results: Granger causality analysis reported a causal relationship where there is no anatomical correlate because of the strong oscillatory behavior of the pyloric circuit. Additionally, we failed to find a direct relationship between synaptic strength and Granger causality in a set of pyloric circuit models. Conclusions: We conclude that the lack of a relationship between synaptic strength and functional connectivity occurs because Granger causality essentially collapses the direct contribution of the synapse with the intrinsic properties of the postsynaptic neuron. We suggest that the richness of the dynamical properties of most biological neurons complicates the simple interpretation of the results of functional connectivity analyses using Granger causality. http://www.neuralsystemsandcircuits.com/content/1/1/9 Tilman Kispersky Gabrielle Gutierrez Eve Marder Neural Systems & Circuits 2011, null:9 2011-05-25T00:00:00Z doi:10.1186/2042-1001-1-9 Understanding circuit function using Granger causality analysis Granger causality is a useful analysis in the context of inhibitory coupling, but the relationship between GC results and actual synaptic strength becomes more complicated when the postsynaptic neurons have more complex intrinsic membrane properties. /content/figures/2042-1001-1-9-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 9 2011-05-25T00:00:00Z XML Although it has been over a century since neuroscientists first conjectured that networks of neurons comprise the brain, technology has limited high-throughput investigations of neural circuitry until very recently. In the last couple of decades, several experimental paradigms have arisen that are poised to finally begin studying neuroanatomy in a high-throughput fashion. In 2005, the term connectome was coined independently by Patric Hagmann and Olaf Sporns, to describe the complete set of neural connections in a brain. Interestingly, both usages seemed to be referring to using Magnetic Resonance Imaging (MRI) to study human brain networks. Shortly thereafter, Narayanan "Bobby" Kasthuri and Jeff Lichtman published an article suggesting that "connectome" should refer to connections between neurons, which one can infer using Electron Microscopy (EM) and fluorescence microscopy (e.g., brainbow animals). "Projectome", they suggested, is more appropriate for MRI based studies. Yet, the word connectome stuck, and now refers to essentially any neuroscientific investigation of the relationship between (collections of) neurons, be they functional or structural. http://www.neuralsystemsandcircuits.com/content/1/1/16 Joshua Vogelstein Neural Systems & Circuits 2011, null:16 2011-11-18T00:00:00Z doi:10.1186/2042-1001-1-16 /content/figures/2042-1001-1-16-toc.gif Neural Systems & Circuits 2042-1001 ${item.volume} 16 2011-11-18T00:00:00Z XML