scholarly journals Graph Properties of the Adult Drosophila Central Brain

2020 ◽  
Author(s):  
Louis K. Scheffer
Keyword(s):  
Experimental Error ◽  
Electrical Response ◽  
Brain Connectome ◽  
Input And Output ◽  
Graph Properties ◽  
Central Brain ◽  
Path Lengths ◽  
Efficient Packing ◽  
Adult Drosophila ◽  
Computational Structures

AbstractThe recent Drosophila central brain connectome offers the possibility of analyzing the graph properties of the fly brain. Crucially, this connectome is dense, meaning all nodes and links are represented, within the limits of experimental error. We consider the connectome as a directed graph with weighted edges. This enables us to look at a number of graph properties, compare them to human designed logic systems, and speculate on how this may affect function. We look at input and output distributions, randomness of wiring, differences between compartments, path lengths, proximity of strong connections, known computational structures, electrical response as a function of compartment structure, and evidence for efficient packing.

scholarly journals Connectomic Underpinnings of Working Memory Deficits in Schizophrenia: Evidence From a replication fMRI study

2020 ◽  
Vol 46 (4) ◽  
pp. 916-926 ◽  
Author(s):  
Jie Yang ◽  
Weidan Pu ◽  
Guowei Wu ◽  
Eric Chen ◽  
Edwin Lee ◽  
...  
Keyword(s):  
Machine Learning ◽  
Working Memory ◽  
Negative Symptoms ◽  
Clinical Symptoms ◽  
Linear Regression Analysis ◽  
Symptom Burden ◽  
Learning Approach ◽  
Brain Connectome ◽  
Graph Properties ◽  
Machine Learning Approach

Abstract Background Working memory (WM) deficit is a key feature of schizophrenia that relates to a generalized neural inefficiency of extensive brain areas. To date, it remains unknown how these distributed regions are systemically organized at the connectome level and how the disruption of such organization brings about the WM impairment seen in schizophrenia. Methods We used graph theory to examine the neural efficiency of the functional connectome in different granularity in 155 patients with schizophrenia and 96 healthy controls during a WM task. These analyses were repeated in another independent dataset (81 patients and 54 controls). Linear regression analysis was used to test associations of altered graph properties, clinical symptoms, and WM accuracy in patients. A machine-learning approach was adopted to study the ability of multivariate connectome features from one dataset to discriminate patients from controls in the second dataset. Results Small-worldness of the whole-brain connectome was significantly increased in schizophrenia during the WM task; this increase is related to better (though subpar) WM accuracy in patients with more severe negative symptom burden. There was a shift in the degree distribution to a more homogeneous form in patients. The machine-learning approach classified a new set of patients from controls with 84.3% true-positivity rate for schizophrenia and 71.6% overall accuracy. Conclusions We demonstrate a putative mechanistic link between connectome topology, hub redistribution, and impaired n-back performance in schizophrenia. The task-dependent modulation of the connectome relates to, but remains inefficient in, improving the performance above par in the presence of severe negative symptoms.

scholarly journals Clonal Development and Organization of the Adult Drosophila Central Brain

2013 ◽  
Vol 23 (8) ◽  
pp. 633-643 ◽  
Author(s):  
Hung-Hsiang Yu ◽  
Takeshi Awasaki ◽  
Mark David Schroeder ◽  
Fuhui Long ◽  
Jacob S. Yang ◽  
...  
Keyword(s):  
Central Brain ◽  
Clonal Development ◽  
Adult Drosophila

Different classes of input and output neurons reveal new features in microglomeruli of the adult Drosophila mushroom body calyx

2012 ◽  
Vol 520 (10) ◽  
pp. 2185-2201 ◽  
Author(s):  
Nancy J. Butcher ◽  
Anja B. Friedrich ◽  
Zhiyuan Lu ◽  
Hiromu Tanimoto ◽  
Ian A. Meinertzhagen
Keyword(s):  
Mushroom Body ◽  
Input And Output ◽  
Output Neurons ◽  
Mushroom Body Calyx ◽  
Adult Drosophila

scholarly journals Local Reasoning for Global Graph Properties

2020 ◽  
pp. 308-335
Author(s):  
Siddharth Krishna ◽  
Alexander J. Summers ◽  
Thomas Wies
Keyword(s):  
Small Region ◽  
Algebraic Equations ◽  
Proof Technique ◽  
Modular Reasoning ◽  
Graph Properties ◽  
Local Modification ◽  
Non Local ◽  
Local Reasoning ◽  
Path Lengths ◽  
Mathematical Foundations

AbstractSeparation logics are widely used for verifying programs that manipulate complex heap-based data structures. These logics build on so-called separation algebras, which allow expressing properties of heap regions such that modifications to a region do not invalidate properties stated about the remainder of the heap. This concept is key to enabling modular reasoning and also extends to concurrency. While heaps are naturally related to mathematical graphs, many ubiquitous graph properties are non-local in character, such as reachability between nodes, path lengths, acyclicity and other structural invariants, as well as data invariants which combine with these notions. Reasoning modularly about such graph properties remains notoriously difficult, since a local modification can have side-effects on a global property that cannot be easily confined to a small region.In this paper, we address the question: What separation algebra can be used to avoid proof arguments reverting back to tedious global reasoning in such cases? To this end, we consider a general class of global graph properties expressed as fixpoints of algebraic equations over graphs. We present mathematical foundations for reasoning about this class of properties, imposing minimal requirements on the underlying theory that allow us to define a suitable separation algebra. Building on this theory, we develop a general proof technique for modular reasoning about global graph properties expressed over program heaps, in a way which can be directly integrated with existing separation logics. To demonstrate our approach, we present local proofs for two challenging examples: a priority inheritance protocol and the non-blocking concurrent Harris list.

scholarly journals Mechanosensory neuron regeneration in adult Drosophila

Development ◽  
2021 ◽  
pp. dev.187534
Author(s):  
Ismael Fernández-Hernández ◽  
Evan B. Marsh ◽  
Michael A. Bonaguidi
Keyword(s):  
Hair Cells ◽  
Neuronal Plasticity ◽  
Lineage Tracing ◽  
Model Systems ◽  
Central Brain ◽  
Brain Circuitry ◽  
Mechanosensory Hair Cells ◽  
Regenerative Therapies ◽  
Self Replication ◽  
Adult Drosophila

Auditory and vestibular mechanosensory hair cells do not regenerate following injury or aging in the adult mammalian inner ear, inducing irreversible hearing loss and balance disorders for millions of people. Research on model systems showing replacement of mechanosensory cells can provide mechanistic insights into developing new regenerative therapies. Here, we developed lineage tracing systems to reveal the generation of mechanosensory neurons in the Johnston's Organ (JO) of intact adult Drosophila, which are the functional counterparts to hair cells in vertebrates. New JO neurons develop cilia and target central brain circuitry. Unexpectedly, mitotic recombination clones point to JO neuron self-replication as a likely source of neuronal plasticity. This mechanism is further enhanced upon treatment with experimental and ototoxic compounds. Our findings introduce a new platform to expedite research on mechanisms and compounds mediating mechanosensory cell regeneration, with nascent implications for hearing and balance restoration.

scholarly journals Author response: A connectome and analysis of the adult Drosophila central brain

2020 ◽  
Author(s):  
Louis K Scheffer ◽  
C Shan Xu ◽  
Michal Januszewski ◽  
Zhiyuan Lu ◽  
Shin-ya Takemura ◽  
...  
Keyword(s):  
Author Response ◽  
Central Brain ◽  
Adult Drosophila

An improved magnetic prism design for a transmission electron microscope energy filter

1978 ◽  
Vol 36 (1) ◽  
pp. 40-41 ◽  
Author(s):  
John W. Andrew ◽  
F.P. Ottensmeyer ◽  
E. Martell
Keyword(s):  
Energy Resolution ◽  
Symmetry Plane ◽  
Fringe Field ◽  
Focal Distance ◽  
Electron Trajectories ◽  
Focusing Effect ◽  
Transmission Electron ◽  
Path Lengths ◽  
Electron Microscopes ◽  
Focusing Properties

Energy selecting electron microscopes of the Castaing-Henry prism-mirror-prism design suffer from a loss of image and energy resolution with increasing field of view. These effects can be qualitatively understood by examining the focusing properties of the prism shown in Fig. 1. A cone of electrons emerges from the entrance lens crossover A and impinges on the planar face of the prism. The task of the prism is to focus these electrons to a point B at a focal distance f2 from the side of the prism. Electrons traveling in the plane of the diagram (i.e., the symmetry plane of the prism) are focused toward point B due to the different path lengths of different electron trajectories in the triangularly shaped magnetic field. This is referred to as horizontal focusing; the better this focusing effect the better the energy resolution of the spectrometer. Electrons in a plane perpendicular to the diagram and containing the central ray of the incident cone are focused toward B by the curved fringe field of the prism.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Sign in / Sign up

Export Citation Format

Share Document