Optimization of a Spherical Decoupled Mechanism for Neuro-Endoscopy Based on Experimental Kinematic Data

ABSTRACTThe neuro-endoscopy is a surgical technique that allows the neurosurgeon to maintain a visual contact while operating inside the brain of a patient. A special instrument called the neuro-endoscope is inserted in the brain until the neurosurgeon reaches his/her target. Its manipulation requires a high level of training for neurosurgeons. To enforce both quality and safety of neuro-endoscopy, we propose a robotic manipulator based on a Spherical Decoupled Mechanism. This mechanical architecture has been modified from a 5-Bar Spherical Linkages and adapted to this medical application. It is able to generate a Remote Center of Motion of 2 Degrees of Freedom. It merges the advantages of parallel mechanisms with the kinematic and control simplicity of decoupled mechanisms, while having a very simple architecture. Motion capture experiments using a brain simulation model have been performed with a team of neurosurgeons to obtain the kinematic data of the neuro-endoscope during brain exploration. Based on the identified workspace, the mechanism has been optimized using kinematic performance and architectural compactness as criteria. An optimum mechanism has been selected, showing better kinematic performances than the original 5-bar spherical linkage mechanism.

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Excitonic Coupled-cluster Theory: Part I, General Formalism

10.26434/chemrxiv.5330773.v2 ◽

2017 ◽

Cited By ~ 1

Author(s):

Yuhong Liu ◽

Anthony Dutoi

Keyword(s):

Electron Correlation ◽

Degrees Of Freedom ◽

Model Systems ◽

Coupled Cluster ◽

Effective Hamiltonian ◽

Coupled Cluster Theory ◽

Cluster Theory ◽

Companion Article ◽

High Level ◽

Fragment Interaction

<div> <div>A shortcoming of presently available fragment-based methods is that electron correlation (if included) is described at the level of individual electrons, resulting in many redundant evaluations of the electronic relaxations associated with any given fluctuation. A generalized variant of coupled-cluster (CC) theory is described, wherein the degrees of freedom are fluctuations of fragments between internally correlated states. The effects of intra-fragment correlation on the inter-fragment interaction is pre-computed and permanently folded into the effective Hamiltonian. This article provides a high-level description of the CC variant, establishing some useful notation, and it demonstrates the advantage of the proposed paradigm numerically on model systems. A companion article shows that the electronic Hamiltonian of real systems may always be cast in the form demanded. This framework opens a promising path to build finely tunable systematically improvable methods to capture precise properties of systems interacting with a large number of other systems. </div> </div>

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Excitonic Coupled-cluster Theory: Part I, General Formalism

10.26434/chemrxiv.5330773.v1 ◽

2017 ◽

Author(s):

Yuhong Liu ◽

Anthony Dutoi

Keyword(s):

Electron Correlation ◽

Degrees Of Freedom ◽

Model Systems ◽

Coupled Cluster ◽

Effective Hamiltonian ◽

Coupled Cluster Theory ◽

Cluster Theory ◽

Companion Article ◽

High Level ◽

Fragment Interaction

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Human Hand Anatomy-Based Prosthetic Hand

Sensors ◽

10.3390/s21010137 ◽

2020 ◽

Vol 21 (1) ◽

pp. 137

Author(s):

Larisa Dunai ◽

Martin Novak ◽

Carmen García Espert

Keyword(s):

3D Printing ◽

Degrees Of Freedom ◽

Use Of Force ◽

Hand Movements ◽

Human Hand ◽

Prosthetic Hand ◽

Object Surface ◽

Hand Phalanges ◽

High Level

The present paper describes the development of a prosthetic hand based on human hand anatomy. The hand phalanges are printed with 3D printing with Polylactic Acid material. One of the main contributions is the investigation on the prosthetic hand joins; the proposed design enables one to create personalized joins that provide the prosthetic hand a high level of movement by increasing the degrees of freedom of the fingers. Moreover, the driven wire tendons show a progressive grasping movement, being the friction of the tendons with the phalanges very low. Another important point is the use of force sensitive resistors (FSR) for simulating the hand touch pressure. These are used for the grasping stop simulating touch pressure of the fingers. Surface Electromyogram (EMG) sensors allow the user to control the prosthetic hand-grasping start. Their use may provide the prosthetic hand the possibility of the classification of the hand movements. The practical results included in the paper prove the importance of the soft joins for the object manipulation and to get adapted to the object surface. Finally, the force sensitive sensors allow the prosthesis to actuate more naturally by adding conditions and classifications to the Electromyogram sensor.

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A neurocognitive model of ideological thinking

Politics and the Life Sciences ◽

10.1017/pls.2021.10 ◽

2021 ◽

pp. 1-15

Author(s):

Leor Zmigrod

Keyword(s):

Empirical Evidence ◽

Motivational Factors ◽

Cognitive Systems ◽

Social Forces ◽

Low Level ◽

Cognitive Principles ◽

High Level ◽

Ideological Attitudes ◽

The Brain

Abstract Ideological behavior has traditionally been viewed as a product of social forces. Nonetheless, an emerging science suggests that ideological worldviews can also be understood in terms of neural and cognitive principles. The article proposes a neurocognitive model of ideological thinking, arguing that ideological worldviews may be manifestations of individuals’ perceptual and cognitive systems. This model makes two claims. First, there are neurocognitive antecedents to ideological thinking: the brain’s low-level neurocognitive dispositions influence its receptivity to ideological doctrines. Second, there are neurocognitive consequences to ideological engagement: strong exposure and adherence to ideological doctrines can shape perceptual and cognitive systems. This article details the neurocognitive model of ideological thinking and synthesizes the empirical evidence in support of its claims. The model postulates that there are bidirectional processes between the brain and the ideological environment, and so it can address the roles of situational and motivational factors in ideologically motivated action. This endeavor highlights that an interdisciplinary neurocognitive approach to ideologies can facilitate biologically informed accounts of the ideological brain and thus reveal who is most susceptible to extreme and authoritarian ideologies. By investigating the relationships between low-level perceptual processes and high-level ideological attitudes, we can develop a better grasp of our collective history as well as the mechanisms that may structure our political futures.

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Perceptual decisions are biased toward relevant prior choices

Scientific Reports ◽

10.1038/s41598-020-80128-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Helen Feigin ◽

Shira Baror ◽

Moshe Bar ◽

Adam Zaidel

Keyword(s):

Sensory Information ◽

Irrelevant Stimulus ◽

Stimulus Feature ◽

Serial Dependence ◽

Low Level ◽

Subsequent Test ◽

Key Factor ◽

High Level ◽

Motor Actions ◽

The Brain

AbstractPerceptual decisions are biased by recent perceptual history—a phenomenon termed 'serial dependence.' Here, we investigated what aspects of perceptual decisions lead to serial dependence, and disambiguated the influences of low-level sensory information, prior choices and motor actions. Participants discriminated whether a brief visual stimulus lay to left/right of the screen center. Following a series of biased ‘prior’ location discriminations, subsequent ‘test’ location discriminations were biased toward the prior choices, even when these were reported via different motor actions (using different keys), and when the prior and test stimuli differed in color. By contrast, prior discriminations about an irrelevant stimulus feature (color) did not substantially influence subsequent location discriminations, even though these were reported via the same motor actions. Additionally, when color (not location) was discriminated, a bias in prior stimulus locations no longer influenced subsequent location discriminations. Although low-level stimuli and motor actions did not trigger serial-dependence on their own, similarity of these features across discriminations boosted the effect. These findings suggest that relevance across perceptual decisions is a key factor for serial dependence. Accordingly, serial dependence likely reflects a high-level mechanism by which the brain predicts and interprets new incoming sensory information in accordance with relevant prior choices.

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A Parallely Actuated Work Support Module for Reconfigurable Machining Systems

Volume 1B: 25th Biennial Mechanisms Conference ◽

10.1115/detc98/mech-5959 ◽

1998 ◽

Author(s):

Venkat Gopalakrishnan ◽

Sridhar Kota

Keyword(s):

Machine Tool ◽

Machine Tools ◽

Degrees Of Freedom ◽

Mechanical Design ◽

Performance Criteria ◽

Machining Accuracy ◽

Parallel Mechanisms ◽

Element Analysis ◽

Work Support ◽

Reconfigurable Machining

Abstract In order to respond quickly to changes in market demands and the resulting product design changes, machine tool manufacturers must reduce the machine tool design lead time and machine set-up time. Reconfigurable Machine Tools (RMTs), assembled from machine modules such as spindles, slides and worktables are designed to be easily reconfigured to accommodate new machining requirements. The essential characteristics of RMTs are modularity, flexibility, convertibility and cost effectiveness. The goal of Reconfigurable Machining Systems (RMSs), composed of RMTs and other types of machines, is to provide exactly the capacity and functionality, exactly when needed. The scope of RMSs design includes mechanical hardware, control systems, process planning and tooling. One of the key challenges in the mechanical design of reconfigurable machine tools is to achieve the desired machining accuracy in all intended machine configurations. To meet this challenge we propose (a) to distribute the total number of degrees of freedom between the work-support and the tool and (b) employ parallely-actuated mechanisms for stiffness and ease of reconfigurability. In this paper we present a novel parallely-actuated work-support module as a part of an RMT. Following a brief summary of a few parallel mechanisms used in machine tool applications, this paper presents a three-degree-of-freedom work-support module designed to meet the machining requirements of specific features on a family of automotive cylinder heads. Inverse kinematics, dynamic and finite element analysis are performed to verify the performance criteria such as workspace envelope and rigidity. A prototype of the proposed module is also presented.

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Vascular responses of dura mater

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1989.257.1.h157 ◽

1989 ◽

Vol 257 (1) ◽

pp. H157-H161 ◽

Cited By ~ 2

Author(s):

F. M. Faraci ◽

K. A. Kadel ◽

D. D. Heistad

Keyword(s):

Blood Flow ◽

Substance P ◽

Dura Mater ◽

Sympathetic Nerves ◽

Vascular Headache ◽

Vascular Responses ◽

Anesthetized Dogs ◽

High Level ◽

The Brain ◽

Increased Blood Flow

The goal of this study was to examine vascular responses of the dura mater. Microspheres were used to measure blood flow to the dura and brain in anesthetized dogs. Under control conditions, blood flow to the dura was 38 +/- 3 (SE) ml.min-1.100 g-1. Values for blood flow to the dura obtained with simultaneous injection of 15- and 50-microns microspheres were similar, which suggests that shunting of 15-microns spheres was minimal. Left atrial infusion of substance P (100 ng.kg-1.min-1) and serotonin (40 micrograms.kg-1.min-1), two agonists that have been reported to increase vascular permeability in the dura, increased blood flow to the dura two- to threefold. Adenosine (iv) produced vasodilatation in the dura. Adenosine and serotonin did not affect cerebral blood flow, but substance P increased blood flow to the brain by approximately 40%. Seizures, which produce pronounced dilatation of cerebral vessels despite activation of sympathetic nerves, produced vasoconstriction in the dura. Thus 1) the dura is perfused at a relatively high level of blood flow under normal conditions and is very responsive to vasoactive stimuli, and 2) substance P and serotonin, which have been implicated in the pathogenesis of vascular headache, produce pronounced vasodilator responses in the dura mater.

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The Use of LEDBased Digital Optical Ministicks as MultiFunctional Controls for Unified HumanMachine Interfaces

Light & Engineering ◽

10.33383/2018-053 ◽

2018 ◽

pp. 188-193

Author(s):

Sergey A. Golubin ◽

Vladimir S. Nikitin ◽

Roman B. Belov

Keyword(s):

Remote Control ◽

Degrees Of Freedom ◽

Light Emitting Diodes ◽

System Control ◽

Visual Contact ◽

Light Emitting ◽

Comparison Results ◽

New Type ◽

Scientific Task ◽

Control Devices

The active development of robotics requires increasingly complex remote control devices. The remote control devices are increasingly large, complex, and expensive. They decrease economic efficiency of robotics and increase their price. The scientific task is the research into possibility of applying optical ministicks on the basis of light emitting diodes as the new type basic multifunctional controls of unified humanmachine interfaces allowing us to control commonly known robotic equipment types using identical devices. During the research original ergonomic methods of purposeful combination of two ministicks on two actuating levers were used so that to provide convenience of tactile control of various robots without visual contact with controls. As a result of the research, new controls were created and patented. They became known as “polyjoysticks” (patent of Russian Federation No. 2497177) and allow controlling engineering facilities having up to 20 degrees of freedom which exceeds the similar parameters of known controls by factor of 3 to 5. Due to combined use of optical ministicks, two polyjoysticks and a video mask, a new generalpurpose generation humanmachine interface was created. It allows controlling various robots and vehicles, from tractor to aircraft. The discussion of the obtained results was carried out by comparing them with parameters of control panels of different robotics systems. The analysis of the comparison results has shown that the controls based on polyjoysticks and digital optical ministicks on the basis of light emitting diodes have the best indices in terms of implemented among known control devices, in terms of ratio of functionality to weight and volume of the devices. New interfaces have already been applied for developing multiagent robotic system control system for fire forest extinguishing.

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A New Paradigm for Training Hyperactive Dopamine Transporter Knockout Rats: Influence of Novel Stimuli on Object Recognition

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2021.654469 ◽

2021 ◽

Vol 15 ◽

Author(s):

Natalia P. Kurzina ◽

Anna B. Volnova ◽

Irina Y. Aristova ◽

Raul R. Gainetdinov

Keyword(s):

Object Recognition ◽

Dopamine Transporter ◽

Cognitive Task ◽

Recognition Task ◽

Long Term Memory ◽

New Paradigm ◽

Dopaminergic Transmission ◽

Novel Objects ◽

High Level ◽

The Brain

Attention deficit hyperactivity disorder (ADHD) is believed to be connected with a high level of hyperactivity caused by alterations of the control of dopaminergic transmission in the brain. The strain of hyperdopaminergic dopamine transporter knockout (DAT-KO) rats represents an optimal model for investigating ADHD-related pathological mechanisms. The goal of this work was to study the influence of the overactivated dopamine system in the brain on a motor cognitive task fulfillment. The DAT-KO rats were trained to learn an object recognition task and store it in long-term memory. We found that DAT-KO rats can learn to move an object and retrieve food from the rewarded familiar objects and not to move the non-rewarded novel objects. However, we observed that the time of task performance and the distances traveled were significantly increased in DAT-KO rats in comparison with wild-type controls. Both groups of rats explored the novel objects longer than the familiar cubes. However, unlike controls, DAT-KO rats explored novel objects significantly longer and with fewer errors, since they preferred not to move the non-rewarded novel objects. After a 3 months’ interval that followed the training period, they were able to retain the learned skills in memory and to efficiently retrieve them. The data obtained indicate that DAT-KO rats have a deficiency in learning the cognitive task, but their hyperactivity does not prevent the ability to learn a non-spatial cognitive task under the presentation of novel stimuli. The longer exploration of novel objects during training may ensure persistent learning of the task paradigm. These findings may serve as a base for developing new ADHD learning paradigms.

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Reconstructing feedback representations in ventral visual pathway with a generative adversarial autoencoder

10.1101/2020.07.23.218859 ◽

2020 ◽

Author(s):

Haider Al-Tahan ◽

Yalda Mohsenzadeh

Keyword(s):

Neural Network ◽

Visual Information ◽

Visual Pathway ◽

Functional Magnetic Resonance ◽

Low Level ◽

Ventral Visual Pathway ◽

High Level ◽

Feedback Connections ◽

The Brain ◽

Insight Into

AbstractWhile vision evokes a dense network of feedforward and feedback neural processes in the brain, visual processes are primarily modeled with feedforward hierarchical neural networks, leaving the computational role of feedback processes poorly understood. Here, we developed a generative autoencoder neural network model and adversarially trained it on a categorically diverse data set of images. We hypothesized that the feedback processes in the ventral visual pathway can be represented by reconstruction of the visual information performed by the generative model. We compared representational similarity of the activity patterns in the proposed model with temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) visual brain responses. The proposed generative model identified two segregated neural dynamics in the visual brain. A temporal hierarchy of processes transforming low level visual information into high level semantics in the feedforward sweep, and a temporally later dynamics of inverse processes reconstructing low level visual information from a high level latent representation in the feedback sweep. Our results append to previous studies on neural feedback processes by presenting a new insight into the algorithmic function and the information carried by the feedback processes in the ventral visual pathway.Author summaryIt has been shown that the ventral visual cortex consists of a dense network of regions with feedforward and feedback connections. The feedforward path processes visual inputs along a hierarchy of cortical areas that starts in early visual cortex (an area tuned to low level features e.g. edges/corners) and ends in inferior temporal cortex (an area that responds to higher level categorical contents e.g. faces/objects). Alternatively, the feedback connections modulate neuronal responses in this hierarchy by broadcasting information from higher to lower areas. In recent years, deep neural network models which are trained on object recognition tasks achieved human-level performance and showed similar activation patterns to the visual brain. In this work, we developed a generative neural network model that consists of encoding and decoding sub-networks. By comparing this computational model with the human brain temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) response patterns, we found that the encoder processes resemble the brain feedforward processing dynamics and the decoder shares similarity with the brain feedback processing dynamics. These results provide an algorithmic insight into the spatiotemporal dynamics of feedforward and feedback processes in biological vision.

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