Computational Consequences of a Bias toward Short Connections

1992 ◽  
Vol 4 (4) ◽  
pp. 323-336 ◽  
Author(s):  
Robert A. Jacobs ◽  
Michael I. Jordan
Keyword(s):  
Short Range ◽  
Adult Brain ◽  
Learning System ◽  
Topographic Maps ◽  
Modular System ◽  
Modular Organization ◽  
Internal Representations ◽  
Modular Systems ◽  
Complementary Approach ◽  
The Brain

A fundamental observation in the neurosciences is that the brain is a modular system in which different regions perform different tasks. Recent evidence, however, raises questions about the accuracy of this characterization with respect to neo-nates. One possible interpretation of this evidence is that certain aspects of the modular organization of the adult brain arise developmentally. To explore this hypothesis we wish to characterize the computational principles that underlie the development of modular systems. In previous work we have considered computational schemes that allow a learning system to discover the modular structure that is present in the environment (Jacobs, Jordan, & Barto, 1991). In the current paper we present a complementary approach in which the development of modularity is due to an architectural bias in the learner. In particular, we examine the computational consequences of a simple architectural bias toward short-range connections. We present simulations that show that systems that learn under the influence of such a bias have a number of desirable properties, including a tendency to decompose tasks into subtasks, to decouple the dynamics of recurrent subsystems, and to develop location-sensitive internal representations. Furthermore, the system's units develop local receptive and projective fields, and the system develops characteristics that are typically associated with topographic maps.

scholarly journals An architectonic type principle in the development of laminar patterns of cortico-cortical connections

2021 ◽  
Author(s):  
Sarah F. Beul ◽  
Alexandros Goulas ◽  
Claus C. Hilgetag
Keyword(s):  
Structural Connectivity ◽  
Macaque Monkey ◽  
Brain Regions ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Cortical Connections ◽  
Cortical Projections ◽  
Structural Connections ◽  
High Degree ◽  
The Brain

AbstractStructural connections between cortical areas form an intricate network with a high degree of specificity. Many aspects of this complex network organization in the adult mammalian cortex are captured by an architectonic type principle, which relates structural connections to the architectonic differentiation of brain regions. In particular, the laminar patterns of projection origins are a prominent feature of structural connections that varies in a graded manner with the relative architectonic differentiation of connected areas in the adult brain. Here we show that the architectonic type principle is already apparent for the laminar origins of cortico-cortical projections in the immature cortex of the macaque monkey. We find that prenatal and neonatal laminar patterns correlate with cortical architectonic differentiation, and that the relation of laminar patterns to architectonic differences between connected areas is not substantially altered by the complete loss of visual input. Moreover, we find that the degree of change in laminar patterns that projections undergo during development varies in proportion to the relative architectonic differentiation of the connected areas. Hence, it appears that initial biases in laminar projection patterns become progressively strengthened by later developmental processes. These findings suggest that early neurogenetic processes during the formation of the brain are sufficient to establish the characteristic laminar projection patterns. This conclusion is in line with previously suggested mechanistic explanations underlying the emergence of the architectonic type principle and provides further constraints for exploring the fundamental factors that shape structural connectivity in the mammalian brain.

scholarly journals The unbalanced reorganization of weaker functional connections induces the altered brain network topology in schizophrenia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rossana Mastrandrea ◽  
Fabrizio Piras ◽  
Andrea Gabrielli ◽  
Nerisa Banaj ◽  
Guido Caldarelli ◽  
...  
Keyword(s):  
Resting State ◽  
Functional Organization ◽  
Functional Integration ◽  
Brain Network ◽  
Modular Organization ◽  
Node Degree ◽  
Imaging Data ◽  
Brain Disorder ◽  
Functional Connections ◽  
The Brain

AbstractNetwork neuroscience shed some light on the functional and structural modifications occurring to the brain associated with the phenomenology of schizophrenia. In particular, resting-state functional networks have helped our understanding of the illness by highlighting the global and local alterations within the cerebral organization. We investigated the robustness of the brain functional architecture in 44 medicated schizophrenic patients and 40 healthy comparators through an advanced network analysis of resting-state functional magnetic resonance imaging data. The networks in patients showed more resistance to disconnection than in healthy controls, with an evident discrepancy between the two groups in the node degree distribution computed along a percolation process. Despite a substantial similarity of the basal functional organization between the two groups, the expected hierarchy of healthy brains' modular organization is crumbled in schizophrenia, showing a peculiar arrangement of the functional connections, characterized by several topologically equivalent backbones. Thus, the manifold nature of the functional organization’s basal scheme, together with its altered hierarchical modularity, may be crucial in the pathogenesis of schizophrenia. This result fits the disconnection hypothesis that describes schizophrenia as a brain disorder characterized by an abnormal functional integration among brain regions.

scholarly journals SUPPORT FOR MANAGING PARTLY CONFIGURABLE MODULAR SYSTEMS

2021 ◽  
Vol 1 ◽  
pp. 2791-2800
Author(s):  
Jarkko Pakkanen ◽  
Teuvo Heikkinen ◽  
Nillo Adlin ◽  
Timo Lehtonen ◽  
Janne Mämmelä ◽  
...  
Keyword(s):  
Portfolio Management ◽  
Product Variety ◽  
Added Value ◽  
Modular System ◽  
Product Management ◽  
Design Decision ◽  
Product Portfolio ◽  
Modular Systems ◽  
Engineer To Order ◽  
The Impact

AbstractThe paper studies what kind of support could be applied to the management of partly configurable modular systems. The main tasks of product management, product portfolio management and product variety management are defined. In addition, a partly configurable product structure and modular system are defined. Because the limited support in the literature for managing partly configurable modular systems, the article reviews previous product development cases in which authors have been involved on lessons learnt basis, i.e., if the methods and tools used in the cases could provide support for the research objective. As a result, the existing definition of the modular system should be extended by the concepts of non-module and design decision sequence description when dealing with partly configurable modular systems. This is because engineer-to-order should be made possible in cases where it brings clear added value to the customer compared to completely pre-defined solutions that may limit the customer's interest in the offering. Tools to assess the impact of changes to the product offering are required. These should be taken into account in frameworks that are used in method and tool development.

scholarly journals The Modular Organization of Pain Brain Networks: An fMRI Graph Analysis Informed by Intracranial EEG

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Camille Fauchon ◽  
David Meunier ◽  
Isabelle Faillenot ◽  
Florence B Pomares ◽  
Hélène Bastuji ◽  
...  
Keyword(s):  
Information Integration ◽  
Functional Organization ◽  
Brain Connectivity ◽  
Brain Networks ◽  
Modular Organization ◽  
Noxious Heat ◽  
Intracranial Eeg ◽  
Brain Connectome ◽  
Posterior Parietal ◽  
The Brain

Abstract Intracranial EEG (iEEG) studies have suggested that the conscious perception of pain builds up from successive contributions of brain networks in less than 1 s. However, the functional organization of cortico-subcortical connections at the multisecond time scale, and its accordance with iEEG models, remains unknown. Here, we used graph theory with modular analysis of fMRI data from 60 healthy participants experiencing noxious heat stimuli, of whom 36 also received audio stimulation. Brain connectivity during pain was organized in four modules matching those identified through iEEG, namely: 1) sensorimotor (SM), 2) medial fronto-cingulo-parietal (default mode-like), 3) posterior parietal-latero-frontal (central executive-like), and 4) amygdalo-hippocampal (limbic). Intrinsic overlaps existed between the pain and audio conditions in high-order areas, but also pain-specific higher small-worldness and connectivity within the sensorimotor module. Neocortical modules were interrelated via “connector hubs” in dorsolateral frontal, posterior parietal, and anterior insular cortices, the antero-insular connector being most predominant during pain. These findings provide a mechanistic picture of the brain networks architecture and support fractal-like similarities between the micro-and macrotemporal dynamics associated with pain. The anterior insula appears to play an essential role in information integration, possibly by determining priorities for the processing of information and subsequent entrance into other points of the brain connectome.

scholarly journals Transfer of rhodamine-123 into the brain and cerebrospinal fluid of fetal, neonatal and adult rats

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Liam M. Koehn ◽  
Katarzyna M. Dziegielewska ◽  
Mark D. Habgood ◽  
Yifan Huang ◽  
Norman R. Saunders
Keyword(s):  
Cerebrospinal Fluid ◽  
Fetal Brain ◽  
Maternal Blood ◽  
Adult Brain ◽  
Rhodamine 123 ◽  
Patient Specific ◽  
Adult Rats ◽  
Blood Brain ◽  
The Brain ◽  
Brain Barriers

Abstract Background Adenosine triphosphate binding cassette transporters such as P-glycoprotein (PGP) play an important role in drug pharmacokinetics by actively effluxing their substrates at barrier interfaces, including the blood-brain, blood-cerebrospinal fluid (CSF) and placental barriers. For a molecule to access the brain during fetal stages it must bypass efflux transporters at both the placental barrier and brain barriers themselves. Following birth, placental protection is no longer present and brain barriers remain the major line of defense. Understanding developmental differences that exist in the transfer of PGP substrates into the brain is important for ensuring that medication regimes are safe and appropriate for all patients. Methods In the present study PGP substrate rhodamine-123 (R123) was injected intraperitoneally into E19 dams, postnatal (P4, P14) and adult rats. Naturally fluorescent properties of R123 were utilized to measure its concentration in blood-plasma, CSF and brain by spectrofluorimetry (Clariostar). Statistical differences in R123 transfer (concentration ratios between tissue and plasma ratios) were determined using Kruskal-Wallis tests with Dunn’s corrections. Results Following maternal injection the transfer of R123 across the E19 placenta from maternal blood to fetal blood was around 20 %. Of the R123 that reached fetal circulation 43 % transferred into brain and 38 % into CSF. The transfer of R123 from blood to brain and CSF was lower in postnatal pups and decreased with age (brain: 43 % at P4, 22 % at P14 and 9 % in adults; CSF: 8 % at P4, 8 % at P14 and 1 % in adults). Transfer from maternal blood across placental and brain barriers into fetal brain was approximately 9 %, similar to the transfer across adult blood-brain barriers (also 9 %). Following birth when placental protection was no longer present, transfer of R123 from blood into the newborn brain was significantly higher than into adult brain (3 fold, p < 0.05). Conclusions Administration of a PGP substrate to infant rats resulted in a higher transfer into the brain than equivalent doses at later stages of life or equivalent maternal doses during gestation. Toxicological testing of PGP substrate drugs should consider the possibility of these patient specific differences in safety analysis.

Analysis of the Waste Volume and CO2-Equivalent Caused by the Use of Selected Patch Pumps

2021 ◽  
pp. 193229682199152
Author(s):  
Jana Winkelkötter ◽  
Thore Reitz
Keyword(s):  
Modular Design ◽  
Insulin Pump ◽  
Raw Materials ◽  
Modular System ◽  
Mass Determination ◽  
Modular Systems ◽  
Use Of Resources ◽  
Manual Sorting ◽  
Free Insulin ◽  
Incineration Residues

Background: The use of tube-free insulin pumps is increasing. To protect the environment, the use of resources and the amount of emissions into the environment should be kept as low as possible when designing these systems. In addition to basic waste avoidance, the composition of the waste produced must be considered. Methods: To compare current tube-free pumps from an ecological standpoint, a tube-free insulin pump with a modular design and two non-modular tube-free pumps were subjected to manual separation, manual sorting, characterization, and mass determination. The annual waste volume of a user was measured, and the recyclability was assessed. The global warming potential (GWP) resulting from extraction of raw materials, energetic utilization of waste, and landfill of the incineration residues was balanced. Results: For the modular tube-free pump, a total waste volume of 5.5 kg/a (recycling percentage 44.3%) was determined. The non-modular systems generated 4.9 kg/a (recycling percentage 14.6%) and 5.1 kg/a (recycling percentage 16.0%) waste. The product-specific GWP of the modular system was approximately 50% lower than that of the non-modular systems; the packaging-specific GWP was 2.5 times higher. In total, a GWP of 13.6 kg CO2-equivalent per year could be determined for the modular system and a GWP of 15.5 kg CO2-equivalent per year for the non-modular systems. Conclusions: Although the modular micropump has a higher total waste volume, a greater ecological potential can be attributed to it. This is based on the recyclability of the system due to its modularity and the possible reduction of packaging waste.

The novel guanylyl cyclase MsGC-I is strongly expressed in higher-order neuropils in the brain of Manduca sexta

2001 ◽  
Vol 204 (2) ◽  
pp. 305-314 ◽  
Author(s):  
A. Nighorn ◽  
P.J. Simpson ◽  
D.B. Morton
Keyword(s):  
Nervous System ◽  
Manduca Sexta ◽  
Guanylyl Cyclase ◽  
Higher Order ◽  
Adult Brain ◽  
Central Complex ◽  
Amino Acid Residues ◽  
Order Processing ◽  
Guanylyl Cyclases ◽  
The Brain

Guanylyl cyclases are usually characterized as being either soluble (sGCs) or receptor (rGCs). We have recently cloned a novel guanylyl cyclase, MsGC-I, from the developing nervous system of the hawkmoth Manduca sexta that cannot be classified as either an sGC or an rGC. MsGC-I shows highest sequence identity with receptor guanylyl cyclases throughout its catalytic and dimerization domains, but does not contain the ligand-binding, transmembrane or kinase-like domains characteristic of receptor guanylyl cyclases. In addition, MsGC-I contains a C-terminal extension of 149 amino acid residues. In this paper, we report the expression of MsGC-I in the adult. Northern blots show that it is expressed preferentially in the nervous system, with high levels in the pharate adult brain and antennae. In the antennae, immunohistochemical analyses show that it is expressed in the cell bodies and dendrites, but not axons, of olfactory receptor neurons. In the brain, it is expressed in a variety of sensory neuropils including the antennal and optic lobes. It is also expressed in structures involved in higher-order processing including the mushroom bodies and central complex. This complicated expression pattern suggests that this novel guanylyl cyclase plays an important role in mediating cyclic GMP levels in the nervous system of Manduca sexta.

Myf5 is a novel early axonal marker in the mouse brain and is subjected to post-transcriptional regulation in neurons

Development ◽  
2000 ◽  
Vol 127 (2) ◽  
pp. 319-331 ◽  
Author(s):  
P. Daubas ◽  
S. Tajbakhsh ◽  
J. Hadchouel ◽  
M. Primig ◽  
M. Buckingham
Keyword(s):  
Transcription Factor ◽  
Mouse Brain ◽  
Mrna Translation ◽  
Adult Brain ◽  
Protein Accumulation ◽  
Embryonic Mouse ◽  
Signalling Molecules ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
The Brain

Myf5 is a key basic Helix-Loop-Helix transcription factor capable of converting many non-muscle cells into muscle. Together with MyoD it is essential for initiating the skeletal muscle programme in the embryo. We previously identified unexpected restricted domains of Myf5 transcription in the embryonic mouse brain, first revealed by Myf5-nlacZ(+/)(−) embryos (Tajbakhsh, S. and Buckingham, M. (1995) Development 121, 4077–4083). We have now further characterized these Myf5 expressing neurons. Retrograde labeling with diI, and the use of a transgenic mouse line expressing lacZ under the control of Myf5 regulatory sequences, show that Myf5 transcription provides a novel axonal marker of the medial longitudinal fasciculus (mlf) and the mammillotegmental tract (mtt), the earliest longitudinal tracts to be established in the embryonic mouse brain. Tracts projecting caudally from the developing olfactory system are also labelled. nlacZ and lacZ expression persist in the adult brain, in a few ventral domains such as the mammillary bodies of the hypothalamus and the interpeduncular nucleus, potentially derived from the embryonic structures where the Myf5 gene is transcribed. To investigate the role of Myf5 in the brain, we monitored Myf5 protein accumulation by immunofluorescence and immunoblotting in neurons transcribing the gene. Although Myf5 was detected in muscle myotomal cells, it was absent in neurons. This would account for the lack of myogenic conversion in brain structures and the absence of a neural phenotype in homozygous null mutants. RT-PCR experiments show that the splicing of Myf5 primary transcripts occurs correctly in neurons, suggesting that the lack of Myf5 protein accumulation is due to regulation at the level of mRNA translation or protein stability. In the embryonic neuroepithelium, Myf5 is transcribed in differentiated neurons after the expression of neural basic Helix-Loop-Helix transcription factors. The signalling molecules Wnt1 and Sonic hedgehog, implicated in the activation of Myf5 in myogenic progenitor cells in the somite, are also produced in the viscinity of the Myf5 expression domain in the mesencephalon. We show that cells expressing Wnt1 can activate neuronal Myf5-nlacZ gene expression in dissected head explants isolated from E9.5 embryos. Furthermore, the gene encoding the basic Helix-Loop-Helix transcription factor mSim1 is expressed in adjacent cells in both the somite and the brain, suggesting that signalling molecules necessary for the activation of mSim1 as well as Myf5 are present at these different sites in the embryo. This phenomenon may be widespread and it remains to be seen how many other potentially potent regulatory genes, in addition to Myf5, when activated do not accumulate protein at inappropriate sites in the embryo.

scholarly journals Effectiveness of lumbar orthoses in low back pain: Review of the literature and our results

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Cordelia Schott ◽  
Sonja Zirke ◽  
Jillian Marie Schmelzle ◽  
Christel Kaiser ◽  
Lluis Aguilar I Fernández
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Randomized Study ◽  
Cost Of Care ◽  
Modular System ◽  
Low Back ◽  
Modular Systems ◽  
Frequency Of Use ◽  
Modular Groups ◽  
The Cost

Back pain and diseases of the spine are today a health disorder of outstanding epidemiological, medical, and health economic importance. The cost of care for patients with lumbosciatic complaints are steadily increasing. Accordingly, the guidelines and treatments are constantly renewed. One concept is the orthotic care. In the following we want to give an overview of the literature and the effectiveness of lumbar orthoses in low back pain supplemented by our own data. A prospective randomized study with 230 patients, divided into three groups, each with two subgroups. Three Orthoses by the TIGGES-Zours GmbH were prescribed; a demountable two-step lumbar orthosis, three-step bridging orthosis and a four-step flexion orthosis modular system. Each were compared to the nonmodular equivalent. All six groups showed improvement in pain intensity and functional capacity at 6 and 12 weeks. The modular groups were found to have improvement in the frequency of use. The subjective effectiveness and sensitivity for the modular and non-modular groups was assessed as being good. In the literature, there are no clear guidelines for an orthotic supply. The studies do not seem to be meaningful and universal due to the difficult ascertainability of pain. There is a need for further research here. Nevertheless, the authors of this review are of the opinion that the implementation of trunk orthoses is void of side effects and beneficial to patients. The modular systems seem to have an advantage as well as higher patient satisfaction.

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