scholarly journals Spontaneous emergence of topologically robust grid cell modules: A multiscale instability theory

2021 ◽  
Author(s):  
Mikail Khona ◽  
Sarthak Chandra ◽  
Ila Fiete
Keyword(s):  
Grid Cell ◽  
Modular Organization ◽  
Lateral Interactions ◽  
Modular Architecture ◽  
Instability Theory ◽  
Cell Modules ◽  
And Function ◽  
Modular Structures ◽  
Cell Data ◽  
The Brain

Modular structures in the brain play a central role in compositionality and intelligence, however the general mechanisms driving module emergence have remained elusive. Studying entorhinal grid cells as paradigmatic examples of modular architecture and function, we demonstrate the spontaneous emergence of a small number of discrete spatial and functional modules from an interplay between continuously varying lateral interactions generated by smooth cortical gradients. We derive a comprehensive analytic theory of modularization, revealing that the process is highly generic with its robustness deriving from topological origins. The theory generates universal predictions for the sequence of grid period ratios, furnishing the most accurate explanation of grid cell data to date. Altogether, this work reveals novel principles by which simple bottom-up dynamical interactions lead to macroscopic modular organization.

scholarly journals Radial structure of dolphin insula

2010 ◽  
Vol 1 (1) ◽  
Author(s):  
Manuel Casanova ◽  
Juan Trippe ◽  
Christopher Tillquist ◽  
Andrew Switala
Keyword(s):  
Mammalian Species ◽  
Insular Cortex ◽  
Structural Motif ◽  
Modular Organization ◽  
Imaging Method ◽  
Cell Arrays ◽  
Human Brains ◽  
High Degree ◽  
Modular Structures ◽  
The Brain

AbstractThe brain of the bottlenose dolphin exhibits patterns of isocortical parcellation and cytoarchitecture distinct from those seen in primates, yet cell clusters in anterior insula are comparable in scale to module-like cell arrangements found throughout isocortex in other placental mammalian species with long divergent evolutionary histories. This similarity may be due to common ancestry, or to convergence as a result of selective constraints on organization of connections within such modules. Differences reflect alternate arrangements of minicolumns, an elemental cytoarchitectonic motif of isocortex defined by radially oriented pyramidal cell arrays. In contrast with larger modular structures incorporating them, minicolumns have been highly conserved in mammalian evolution. In this study a previously validated imaging method was employed to assess verticality, D, a parameter indicating radial bias of isocortex. Photomicrographs of coronal Nissl-stained sections of dolphin anterior insular cortex were compared with sections from human brains of putatively homologous areas as well as other isocortical areas differing in modular organization. Dolphin insula exhibited a high degree of verticality consistent with conserved minicolumnar organization. Our findings indicate that a basic structural motif of isocortex is synapomorphic in a species of marine mammal exhibiting unique phylogenetically derived isocortical characteristics.

Using Computational Modelling to Understand Cognition in the Ventral Visual-Perirhinal Pathway

2011 ◽  
pp. 15-45 ◽  
Author(s):  
Rosemary A. Cowell ◽  
Timothy J. Bussey ◽  
Lisa M. Saksida
Keyword(s):  
Visual Memory ◽  
Computational Models ◽  
Computational Modelling ◽  
Modular Organization ◽  
Object Representations ◽  
Object Processing ◽  
Representational System ◽  
Object Recognition Memory ◽  
And Function ◽  
The Brain

The authors present a series of studies in which computational models are used as a tool to examine the organization and function of the ventral visual-perirhinal stream in the brain. The prevailing theoretical view in this area of cognitive neuroscience holds that the object-processing pathway has a modular organization, in which visual perception and visual memory are carried out independently. They use computational simulations to demonstrate that the effects of brain damage on both visual discrimination and object recognition memory may not be due to an impairment in a specific function such as memory or perception, but are more likely due to compromised object representations in a hierarchical and continuous representational system. The authors argue that examining the nature of stimulus representations and their processing in cortex is a more fruitful approach than attempting to map cognition onto functional modules.

Entorhinal Cortex

2017 ◽  
pp. 227-244
Author(s):  
Edvard I. Moser ◽  
Menno P. Witter ◽  
May-Britt Moser
Keyword(s):  
Entorhinal Cortex ◽  
Grid Cell ◽  
Cell Types ◽  
Structure And Function ◽  
Modular Organization ◽  
Head Direction ◽  
Head Direction Cells ◽  
Terra Incognita ◽  
And Function ◽  
Hippocampal Structure

While decades of study have unraveled some of the basic principles of hippocampal structure and function, the adjacent entorhinal cortex (EC) has remained terra incognita in many respects. Recent studies suggest that the medial part of the entorhinal cortex is part of a two-dimensional metric map of the animal’s changing location in the environment. A key component of this map is the grid cell, which fires selectively at hexagonally spaced positions in the animal’s environment. Grid cells colocalize with other recently discovered medial entorhinal cell types, such as head direction cells, conjunctive grid × head direction cells, border cells, and speed cells. This chapter provides an overview of these functional cell types, their possible relationship to morphological cell types, the intrinsic architecture of the system (including laminar, longitudinal, and modular organization), and the extrinsic connectivity and possible function of both the medial and lateral subdivisions of the entorhinal cortex.

scholarly journals Impact of modular organization on dynamical richness in cortical networks

2018 ◽  
Vol 4 (11) ◽  
pp. eaau4914 ◽  
Author(s):  
Hideaki Yamamoto ◽  
Satoshi Moriya ◽  
Katsuya Ide ◽  
Takeshi Hayakawa ◽  
Hisanao Akima ◽  
...  
Keyword(s):  
Modular Organization ◽  
Modular Architecture ◽  
Cortical Networks ◽  
Trade Off ◽  
In Silico Modeling ◽  
Functional Advantage ◽  
Microfabrication Technology ◽  
The Brain ◽  
Global Activity

As in many naturally formed networks, the brain exhibits an inherent modular architecture that is the basis of its rich operability, robustness, and integration-segregation capacity. However, the mechanisms that allow spatially segregated neuronal assemblies to swiftly change from localized to global activity remain unclear. Here, we integrate microfabrication technology with in vitro cortical networks to investigate the dynamical repertoire and functional traits of four interconnected neuronal modules. We show that the coupling among modules is central. The highest dynamical richness of the network emerges at a critical connectivity at the verge of physical disconnection. Stronger coupling leads to a persistently coherent activity among the modules, while weaker coupling precipitates the activity to be localized solely within the modules. An in silico modeling of the experiments reveals that the advent of coherence is mediated by a trade-off between connectivity and subquorum firing, a mechanism flexible enough to allow for the coexistence of both segregated and integrated activities. Our results unveil a new functional advantage of modular organization in complex networks of nonlinear units.

scholarly journals Optimal modularity and memory capacity of neural reservoirs

2019 ◽  
Vol 3 (2) ◽  
pp. 551-566 ◽  
Author(s):  
Nathaniel Rodriguez ◽  
Eduardo Izquierdo ◽  
Yong-Yeol Ahn
Keyword(s):  
Neural Networks ◽  
Memory Performance ◽  
Biological Evolution ◽  
Vital Role ◽  
Dynamical Analysis ◽  
Modular Organization ◽  
Modular Architecture ◽  
The Neural Network ◽  
And Function ◽  
Local Cohesion

The neural network is a powerful computing framework that has been exploited by biological evolution and by humans for solving diverse problems. Although the computational capabilities of neural networks are determined by their structure, the current understanding of the relationships between a neural network’s architecture and function is still primitive. Here we reveal that a neural network’s modular architecture plays a vital role in determining the neural dynamics and memory performance of the network of threshold neurons. In particular, we demonstrate that there exists an optimal modularity for memory performance, where a balance between local cohesion and global connectivity is established, allowing optimally modular networks to remember longer. Our results suggest that insights from dynamical analysis of neural networks and information-spreading processes can be leveraged to better design neural networks and may shed light on the brain’s modular organization.

scholarly journals Development and function explain the modular evolution of phalanges in gecko lizards

2022 ◽  
Vol 289 (1966) ◽  
Author(s):  
Priscila S. Rothier ◽  
Monique N. Simon ◽  
Gabriel Marroig ◽  
Anthony Herrel ◽  
Tiana Kohlsdorf
Keyword(s):  
Functional Module ◽  
Empirical Support ◽  
Phenotypic Traits ◽  
Functional Specialization ◽  
Modular Architecture ◽  
Hand Bones ◽  
Modular Evolution ◽  
History Of ◽  
And Function ◽  
Modular Structures

Selective regimes favouring the evolution of functional specialization probably affect covariation among phenotypic traits. Phalanges of most tetrapods develop from a conserved module that constrains their relative proportions. In geckos, however, biomechanical specializations associated with adhesive toepads involve morphological variation in the autopodium and might reorganize such modular structures. We tested two hypotheses to explain the modular architecture of hand bones in geckos, one based on developmental interactions and another incorporating functional associations related to locomotion, and compared the empirical support for each hypothetical module between padded and padless lineages. We found strong evidence for developmental modules in most species, which probably reflects embryological constraints during phalangeal formation. Although padded geckos exhibit a functional specialization involving the hyperextension of the distal phalanges that is absent in padless species, the padless species are the ones that show a distal functional module with high integration. Some ancestrally padless geckos apparently deviate from developmental predictions and present a relatively weak developmental module of phalanges and a strongly integrated distal module, which may reflect selective regimes involving incipient frictional adhesion in digit morphology. Modularity of digit elements seems dynamic along the evolutionary history of geckos, being associated with the presence/absence of adhesive toepads.

Ultrastructure of developing visual cortical synapses in the cat superior colliculus

1991 ◽  
Vol 49 ◽  
pp. 156-157
Author(s):  
Caroline A. Miller ◽  
Laura L. Bruce
Keyword(s):  
Superior Colliculus ◽  
Phosphate Buffer ◽  
Receptive Fields ◽  
Visual Cortical Area ◽  
Cortical Synapses ◽  
Visual Cortical ◽  
And Function ◽  
Phosphate Buffered Saline ◽  
The Brain ◽  
Cat Superior Colliculus

The first visual cortical axons arrive in the cat superior colliculus by the time of birth. Adultlike receptive fields develop slowly over several weeks following birth. The developing cortical axons go through a sequence of changes before acquiring their adultlike morphology and function. To determine how these axons interact with neurons in the colliculus, cortico-collicular axons were labeled with biocytin (an anterograde neuronal tracer) and studied with electron microscopy.Deeply anesthetized animals received 200-500 nl injections of biocytin (Sigma; 5% in phosphate buffer) in the lateral suprasylvian visual cortical area. After a 24 hr survival time, the animals were deeply anesthetized and perfused with 0.9% phosphate buffered saline followed by fixation with a solution of 1.25% glutaraldehyde and 1.0% paraformaldehyde in 0.1M phosphate buffer. The brain was sectioned transversely on a vibratome at 50 μm. The tissue was processed immediately to visualize the biocytin.

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.

Revision Targeted Muscle Reinnervation Improves Secondary Pain Insult in an Upper Extremity Amputee: A Case Report

Hand ◽  
2021 ◽  
pp. 155894472199246
Author(s):  
David D. Rivedal ◽  
Meng Guo ◽  
James Sanger ◽  
Aaron Morgan
Keyword(s):  
Neuropathic Pain ◽  
Peripheral Nerves ◽  
Nerve Biopsy ◽  
Sensory Cortex ◽  
Denervated Muscle ◽  
Unique Case ◽  
Targeted Muscle Reinnervation ◽  
Muscle Reinnervation ◽  
And Function ◽  
The Brain

Targeted muscle reinnervation (TMR) has been shown to improve phantom and neuropathic pain in both the acute and chronic amputee population. Through rerouting of major peripheral nerves into a newly denervated muscle, TMR harnesses the plasticity of the brain, helping to revert the sensory cortex back toward the preinsult state, effectively reducing pain. We highlight a unique case of an above-elbow amputee for sarcoma who was initially treated with successful transhumeral TMR. Following inadvertent nerve biopsy of a TMR coaptation site, his pain returned, and he was unable to don his prosthetic. Revision of his TMR to a more proximal level was performed, providing improved pain and function of the amputated arm. This is the first report to highlight the concept of secondary neuroplasticity and successful proximal TMR revision in the setting of multiple insults to the same extremity.

scholarly journals The Ncoa7 locus regulates V-ATPase formation and function, neurodevelopment and behaviour

2020 ◽  
Author(s):  
Enrico Castroflorio ◽  
Joery den Hoed ◽  
Daria Svistunova ◽  
Mattéa J. Finelli ◽  
Alberto Cebrian-Serrano ◽  
...  
Keyword(s):  
Neurodevelopmental Disorders ◽  
Regulatory Protein ◽  
Molecular Function ◽  
Neuronal Connectivity ◽  
Nuclear Receptor Coactivator ◽  
Lysm Domain ◽  
Behavioural Assessment ◽  
And Function ◽  
The Brain

Abstract Members of the Tre2/Bub2/Cdc16 (TBC), lysin motif (LysM), domain catalytic (TLDc) protein family are associated with multiple neurodevelopmental disorders, although their exact roles in disease remain unclear. For example, nuclear receptor coactivator 7 (NCOA7) has been associated with autism, although almost nothing is known regarding the mode-of-action of this TLDc protein in the nervous system. Here we investigated the molecular function of NCOA7 in neurons and generated a novel mouse model to determine the consequences of deleting this locus in vivo. We show that NCOA7 interacts with the cytoplasmic domain of the vacuolar (V)-ATPase in the brain and demonstrate that this protein is required for normal assembly and activity of this critical proton pump. Neurons lacking Ncoa7 exhibit altered development alongside defective lysosomal formation and function; accordingly, Ncoa7 deletion animals exhibited abnormal neuronal patterning defects and a reduced expression of lysosomal markers. Furthermore, behavioural assessment revealed anxiety and social defects in mice lacking Ncoa7. In summary, we demonstrate that NCOA7 is an important V-ATPase regulatory protein in the brain, modulating lysosomal function, neuronal connectivity and behaviour; thus our study reveals a molecular mechanism controlling endolysosomal homeostasis that is essential for neurodevelopment. Graphic abstract

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