Noncommutative Control in the Rotational Vestibuloocular Reflex

2008 ◽  
Vol 99 (1) ◽  
pp. 96-111 ◽  
Author(s):  
Tamara Tchelidze ◽  
Bernhard J. M. Hess
Keyword(s):  
Three Dimensional ◽  
Oculomotor System ◽  
Head Orientation ◽  
Complete Darkness ◽  
Quantitative Analyses ◽  
The Subject ◽  
Roll Axis ◽  
Eye Velocity ◽  
The Brain

To investigate the role of noncommutative computations in the oculomotor system, three-dimensional (3D) eye movements were measured in seven healthy subjects using a memory-contingent vestibulooculomotor paradigm. Subjects had to fixate a luminous point target that appeared briefly at an eccentricity of 20° in one of four diagonal directions in otherwise complete darkness. After a fixation period of ∼1 s, the subject was moved through a sequence of two rotations about mutually orthogonal axes in one of two orders (30° yaw followed by 30° pitch and vice versa in upright and 30° yaw followed by 20° roll and vice versa in both upright and supine orientations). We found that the change in ocular torsion induced by consecutive rotations about the yaw and the pitch axis depended on the order of rotations as predicted by 3D rotation kinematics. Similarly, after rotations about the yaw and roll axis, torsion depended on the order of rotations but now due to the change in final head orientation relative to gravity. Quantitative analyses of these ocular responses revealed that the rotational vestibuloocular reflexes (VORs) in far vision closely matched the predictions of 3D rotation kinematics. We conclude that the brain uses an optimal VOR strategy with the restriction of a reduced torsional position gain. This restriction implies a limited oculomotor range in torsion and systematic tilts of the angular eye velocity as a function of gaze direction.

Role of Cerebellar Uvula-Nodulus in the Control of Head Orientation-Specific Eye Velocity in the Rabbit

1996 ◽  
Vol 781 (1 Lipids and Sy) ◽  
pp. 614-618 ◽  
Author(s):  
P. ERRICO ◽  
A. A. FERRARESI ◽  
N. H. BARMACK ◽  
V. E. PETTOROSSF
Keyword(s):  
Head Orientation ◽  
Eye Velocity

Implications of rotational kinematics for the oculomotor system in three dimensions

1987 ◽  
Vol 58 (4) ◽  
pp. 832-849 ◽  
Author(s):  
D. Tweed ◽  
T. Vilis
Keyword(s):  
Three Dimensional ◽  
Oculomotor System ◽  
Three Dimensions ◽  
Eye Position ◽  
Head Velocity ◽  
Listing’S Law ◽  
Indirect Path ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Eye Velocity

1. This paper develops three-dimensional models for the vestibuloocular reflex (VOR) and the internal feedback loop of the saccadic system. The models differ qualitatively from previous, one-dimensional versions, because the commutative algebra used in previous models does not apply to the three-dimensional rotations of the eye. 2. The hypothesis that eye position signals are generated by an eye velocity integrator in the indirect path of the VOR must be rejected because in three dimensions the integral of angular velocity does not specify angular position. Computer simulations using eye velocity integrators show large, cumulative gaze errors and post-VOR drift. We describe a simple velocity to position transformation that works in three dimensions. 3. In the feedback control of saccades, eye position error is not the vector difference between actual and desired eye positions. Subtractive feedback models must continuously adjust the axis of rotation throughout a saccade, and they generate meandering, dysmetric gaze saccades. We describe a multiplicative feedback system that solves these problems and generates fixed-axis saccades that accord with Listing's law. 4. We show that Listing's law requires that most saccades have their axes out of Listing's plane. A corollary is that if three pools of short-lead burst neurons code the eye velocity command during saccades, the three pools are not yoked, but function independently during visually triggered saccades. 5. In our three-dimensional models, we represent eye position using four-component rotational operators called quaternions. This is not the only algebraic system for describing rotations, but it is the one that best fits the needs of the oculomotor system, and it yields much simpler models than do rotation matrix or other representations. 6. Quaternion models predict that eye position is represented on four channels in the oculomotor system: three for the vector components of eye position and one inversely related to gaze eccentricity and torsion. 7. Many testable predictions made by quaternion models also turn up in models based on other mathematics. These predictions are therefore more fundamental than the specific models that generate them. Among these predictions are 1) to compute eye position in the indirect path of the VOR, eye or head velocity signals are multiplied by eye position feedback and then integrated; consequently 2) eye position signals and eye or head velocity signals converge on vestibular neurons, and their interaction is multiplicative.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Is There a Link between Oropharyngeal Microbiome and Schizophrenia? A Narrative Review

2022 ◽  
Vol 23 (2) ◽  
pp. 846
Author(s):  
Stanislas Martin ◽  
Audrey Foulon ◽  
Wissam El Hage ◽  
Diane Dufour-Rainfray ◽  
Frédéric Denis
Keyword(s):  
Periodontal Disease ◽  
Research Team ◽  
Oral Microbiome ◽  
Oral Microbiota ◽  
Future Studies ◽  
The Subject ◽  
The Moment ◽  
The Impact ◽  
The Brain

The study aimed to examine the impact of the oropharyngeal microbiome in the pathophysiology of schizophrenia and to clarify whether there might be a bidirectional link between the oral microbiota and the brain in a context of dysbiosis-related neuroinflammation. We selected nine articles including three systemic reviews with several articles from the same research team. Different themes emerged, which we grouped into 5 distinct parts concerning the oropharyngeal phageome, the oropharyngeal microbiome, the salivary microbiome and periodontal disease potentially associated with schizophrenia, and the impact of drugs on the microbiome and schizophrenia. We pointed out the presence of phageoma in patients suffering from schizophrenia and that periodontal disease reinforces the role of inflammation in the pathophysiology of schizophrenia. Moreover, saliva could be an interesting substrate to characterize the different stages of schizophrenia. However, the few studies we have on the subject are limited in scope, and some of them are the work of a single team. At this stage of knowledge, it is difficult to conclude on the existence of a bidirectional link between the brain and the oral microbiome. Future studies on the subject will clarify these questions that for the moment remain unresolved.

Drugs and Drug Policy

2011 ◽  
Author(s):  
Mark A.R. Kleiman ◽  
Jonathan P. Caulkins ◽  
Angela Hawken
Keyword(s):  
Drug Policy ◽  
Illicit Trade ◽  
Beneficial Effects ◽  
Control Drug ◽  
The Subject ◽  
Drugs And Crime ◽  
The Relationship ◽  
Drug Free ◽  
The Brain

While there have always been norms and customs around the use of drugs, explicit public policies--regulations, taxes, and prohibitions--designed to control drug abuse are a more recent phenomenon. Those policies sometimes have terrible side-effects: most prominently the development of criminal enterprises dealing in forbidden (or untaxed) drugs and the use of the profits of drug-dealing to finance insurgency and terrorism. Neither a drug-free world nor a world of free drugs seems to be on offer, leaving citizens and officials to face the age-old problem: What are we going to do about drugs? In Drugs and Drug Policy, three noted authorities survey the subject with exceptional clarity, in this addition to the acclaimed series, What Everyone Needs to Know. They begin by, defining "drugs, " examining how they work in the brain, discussing the nature of addiction, and exploring the damage they do to users. The book moves on to policy, answering questions about legalization, the role of criminal prohibitions, and the relative legal tolerance for alcohol and tobacco. The authors then dissect the illicit trade, from street dealers to the flow of money to the effect of catching kingpins, and show the precise nature of the relationship between drugs and crime. They examine treatment, both its effectiveness and the role of public policy, and discuss the beneficial effects of some abusable substances. Finally they move outward to look at the role of drugs in our foreign policy, their relationship to terrorism, and the ugly politics that surround the issue. Crisp, clear, and comprehensive, this is a handy and up-to-date overview of one of the most pressing topics in today's world.

scholarly journals Reviewing the State-of-the-Art of Smart Cities in Portugal: Evidence Based on Content Analysis of a Portuguese Magazine

Publications ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 49
Author(s):  
Diogo Correia ◽  
Leonor Teixeira ◽  
João Lourenço Marques
Keyword(s):  
Smart City ◽  
State Of The Art ◽  
Smart Cities ◽  
The State ◽  
Role Of Government ◽  
Quantitative Analyses ◽  
Subject Areas ◽  
The Subject

The lack of examples of smart-city initiatives and the sharing of best practices in Portugal confirm the gap in the transference of empirical knowledge to the scientific literature in this area. The smart-city concept has passed through three stages. However, its evolution has not been noted equally throughout countries and their territories. The literature only provides information about specific projects implemented in a few cities. Therefore, the aim of this paper was to study the state-of-the-art of smart cities in Portugal by analyzing 25 editions of the most relevant national-wide smart-cities magazine. First, the objective of analyzing the magazine was to study each Portuguese city in terms of the subject areas and types of existing initiatives in order, ultimately, to frame cities within their respective smart-city phases, as per the literature. Second, the aim of the paper was also to provide information about the evolution of the concept through analyses of embedded experts’ quotes. The results of the first are complemented with the analysis of interviews with policymakers to provide information about the existing challenges to implementing a smart city and to understand the role of government therein. Qualitative and quantitative analyses were performed on the case study. The findings suggest that the three smart-city phases are perceived in slightly different ways in Portugal and heterogeneity within the country can be noted from the lack of strategies and a standard framework.

Media and Religious Tourism

2021 ◽  
pp. 210-231
Author(s):  
Rizwan Shabbir ◽  
Aysha Batool
Keyword(s):  
Thematic Analysis ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Tourist Behavior ◽  
Visitor Management ◽  
Religious Tourism ◽  
The Subject ◽  
Socio Economic Impact ◽  
Research Domains

This chapter aims at presenting a thematic analysis of 64 research articles on religious tourism published from 2009 to 2020 by adopting a systematic literature review method. The results indicate that prominent topics discussed were amplification of concepts, tourist motivations, and experience. The evolution of religious tourism concept through nexus of diverse scholarly terms, related domains, and religious practices needs a comprehensive literary debate to refine the subject. The socio-economic impact of religious tourism also calls for the enrichment of topics on scholarly and practical grounds. Issues such as host and tourist behavior, social interaction, visitor management, marketing components, and the role of media need to be explored for the progression of religious tourism in line with sustainability. The chapter contributes to the literature by proposing a three-dimensional model focusing on the role of media and potential research domains for further exploration.

Experience and design: Bringing in the brain

2021 ◽  
pp. 571-642
Author(s):  
Michael A. Arbib
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Memory Systems ◽  
External Memory ◽  
Collaborative Studies ◽  
Current Design ◽  
Long Term Working Memory ◽  
The Brain

The IBSEN model of Imagination in Brain Systems for Episodes and Navigation explores how the architect’s experience is brought to bear in the design of architecture by building on the VISIONS model of understanding a visual scene and the TAM-WGM model of navigation. IBSEN develops the idea that a building provides both views from various viewpoints and places where particular experiences can be felt, and actions can be performed. For this, the design must support a variety of scripts for both practical and contemplative action and the cognitive maps that relate places for them. Nodes from different maps may be combined as scripts are harmonized with respect to a specific embedding of places in three-dimensional space. The chapter examines the role of the hippocampus in episodic memory and imagination, and observes that memory and imagination, episodic or not, are construction processes. During design, long-term working memory links internal and external memory systems, providing priority access to (but not only to) memory fragments that have proved relevant to the current design process. The designer in some sense “inverts” imagined experiences and behaviors of users of the forthcoming building. As the book ends, the author notes that we are only at the beginning of new collaborative studies that take cog/neuroscience out of the lab and into the building and the street.

scholarly journals V. On the modifications of the spectrum of potassium which are effected by the presence of phosphoric acid, and on the inorganic bases and salts which are found in combination with educts of the brain

1880 ◽  
Vol 30 (200-205) ◽  
pp. 278-286 ◽  
Keyword(s):  
Nitric Acid ◽  
Phosphoric Acid ◽  
Royal Society ◽  
Potassium Salt ◽  
Extraction Process ◽  
Dilute Solution ◽  
Metaphosphoric Acid ◽  
Quantitative Analyses ◽  
The Subject ◽  
The Brain

Among the results of a large investigation on which I have for many years been engaged in regard of the chemistry of the brain, I had been led to conclude that the so-called “ protagon” of Oscar Liebreich is not a definite chemical body, but is a variable mixture of several bodies. This conclusion of mine (which agrees with opinions expressed on the same subject by Strecker, Diaconow, and HoppeSeyler) was published by me in 1874, and endeavours to controvert it have since then been made, on several occasions, by Dr. Arthur Gamgee. Last summer, he brought before the Royal Society his contentions for the chemical individuality of “protagon”; and it fortunately was in my power shortly afterwards to publish evidence, which, I believe, those who will take the trouble to follow it will find quite unanswerable, that Dr. Gamgee’s contentions were mistaken.§ Part of my evidence to that effect consisted in showing by quantitative analyses that Dr. Gamgee’s so-called “ protagon” contains 0·7 per cent, of potassium; secondly, that in connexion with trifling differences in the extraction process, the proportion of potassium in different specimens of “protagon” can be made to range from a trace to 1·6 per cent.; thirdly, that with the variable quantities of potassium the quantities of phosphorus and other ingredients will also vary. In the last published number, No. 200, p. 111, of the “Proceedings of the Royal Society,” I find that Dr. Gamgee has recently brought the question again under notice of the Society, and that, in doing so, he especially rests his case upon the following statement made by his colleague, Professor Roscoe, on the subject of some examinations, which, at Dr. Gamgee’s request, he had made for him: see “ Proceedings,” vol. xxx, p. 113:—“I have examined spectroscopically for potash a sample of protagon furnished me by Dr. Gamgee, and labelled ‘Protagon, twice recrystallised, Blankenhom.’ I could not detect any potash by the spectroscope in the incinerated mass from 0·1 grm. of substance. With the carbonised mass obtained from 1·0 grm. of substance I obtained the potasssium line ( α ) very faintly, and from comparative experiments with a dilute solution of a potassium salt I estimate the quantity of potash in 1 grm. of the substance Lot to exceed 1/20 mgrm. The carbonised residue of 1 grm. of protagon was carefully oxidised with pure nitric acid, when a small quantity of fused metaphosphoric acid remained after ignition. The residue weighed 0·0278 grm., corresponding to 1·08 per cent, of phosphorus.— (Signed) H. E. Roscoe.”

scholarly journals Computations underlying the visuomotor transformation for smooth pursuit eye movements

2015 ◽  
Vol 113 (5) ◽  
pp. 1377-1399 ◽  
Author(s):  
T. Scott Murdison ◽  
Guillaume Leclercq ◽  
Philippe Lefèvre ◽  
Gunnar Blohm
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Reference Frames ◽  
Three Dimensional ◽  
Head Orientation ◽  
Smooth Pursuit Eye Movements ◽  
Visuomotor Transformation ◽  
Pursuit Eye Movements ◽  
Retinal Motion ◽  
The Brain

Smooth pursuit eye movements are driven by retinal motion and enable us to view moving targets with high acuity. Complicating the generation of these movements is the fact that different eye and head rotations can produce different retinal stimuli but giving rise to identical smooth pursuit trajectories. However, because our eyes accurately pursue targets regardless of eye and head orientation (Blohm G, Lefèvre P. J Neurophysiol 104: 2103–2115, 2010), the brain must somehow take these signals into account. To learn about the neural mechanisms potentially underlying this visual-to-motor transformation, we trained a physiologically inspired neural network model to combine two-dimensional (2D) retinal motion signals with three-dimensional (3D) eye and head orientation and velocity signals to generate a spatially correct 3D pursuit command. We then simulated conditions of 1) head roll-induced ocular counterroll, 2) oblique gaze-induced retinal rotations, 3) eccentric gazes (invoking the half-angle rule), and 4) optokinetic nystagmus to investigate how units in the intermediate layers of the network accounted for different 3D constraints. Simultaneously, we simulated electrophysiological recordings (visual and motor tunings) and microstimulation experiments to quantify the reference frames of signals at each processing stage. We found a gradual retinal-to-intermediate-to-spatial feedforward transformation through the hidden layers. Our model is the first to describe the general 3D transformation for smooth pursuit mediated by eye- and head-dependent gain modulation. Based on several testable experimental predictions, our model provides a mechanism by which the brain could perform the 3D visuomotor transformation for smooth pursuit.

scholarly journals The role of cytokines in the processes of adaptive integration of immune and neuroendocrine reactions of the human body

2021 ◽  
Vol 67 (2) ◽  
pp. 4-9
Author(s):  
E. A. Troshina
Keyword(s):  
Immune Responses ◽  
Therapeutic Strategies ◽  
Main Task ◽  
Combined Effects ◽  
Immune Stimulation ◽  
Adaptive Integration ◽  
The Subject ◽  
To Receive ◽  
The Brain

The immune, endocrine and nervous systems are integrated due to the existence of reciprocal pathways for transmitting information about changes in their actual functional state. The main task of the brain is to receive, integrate and store information, and there is strong evidence that this also applies to information obtained through the body’s immune responses. It has been proven that the production of cytokines in the brain can be caused not only by peripheral immune stimulation, but also by the nerve cells themselves, stimulated by certain neurosensory signals. Evolutionarily preserved antihomeostatic mechanisms characteristic of specific diseases are the subject of further research, the results of which may be very important for the development of therapeutic strategies that would prevent the undesirable combined effects of immune and neuroendocrine mediators.

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