Sensory regulation of quadrupedal locomotion: a top-down or bottom-up control system?

2012 ◽  
Vol 108 (3) ◽  
pp. 709-711 ◽  
Author(s):  
Yann Thibaudier ◽  
Marie-France Hurteau
Keyword(s):  
Control System ◽  
Central Pattern Generators ◽  
Top Down ◽  
Bottom Up ◽  
Sensory Inputs ◽  
Sensory Regulation ◽  
Before And After ◽  
Pattern Generators

Propriospinal pathways are thought to be critical for quadrupedal coordination by coupling cervical and lumbar central pattern generators (CPGs). However, the mechanisms involved in relaying information between girdles remain largely unexplored. Using an in vitro spinal cord preparation in neonatal rats, Juvin and colleagues ( Juvin et al. 2012 ) have recently shown sensory inputs from the hindlimbs have greater influence on forelimb CPGs than forelimb sensory inputs on hindlimb CPGs, in other words, a bottom-up control system. However, results from decerebrate cats suggest a top-down control system. It may be that both bottom-up and top-down control systems exist and that the dominance of one over the other is task or context dependent. As such, the role of sensory inputs in controlling quadrupedal coordination before and after injury requires further investigation.

scholarly journals The Functional Connectivity between the Locust Leg Pattern Generating Networks and the Subesophageal Ganglion Higher Motor Center

2017 ◽  
Author(s):  
Daniel Knebel ◽  
Jan Rillich ◽  
Leonard Nadler ◽  
Hans-Joachim Pflueger ◽  
Amir Ayali
Keyword(s):  
Motor Neurons ◽  
Central Pattern Generators ◽  
Subesophageal Ganglion ◽  
Motor Center ◽  
Coupling Pattern ◽  
Descending Interneurons ◽  
Pattern Generators ◽  
Leg Movements

AbstractInteractions among different neuronal circuits are essential for adaptable coordinated behavior. Specifically, higher motor centers and central pattern generators (CPGs) induce rhythmic leg movements that act in concert in the control of locomotion. Here we explored the relations between the subesophageal ganglion (SEG) and thoracic leg CPGs in the desert locust. Backfill staining revealed about 300 SEG descending interneurons (DINs) and some overlap with the arborization of DINs and leg motor neurons. In accordance, in in-vitro preparations, electrical stimulation applied to the SEG excited these neurons, and in some cases also induced CPGs activity. Additionally, we found that the SEG regulates the coupling pattern among the CPGs: when the CPGs were activated pharmacologically, inputs from the SEG were able to synchronize contralateral CPGs. This motor output was correlated to the firing of SEG descending and local interneurons. Altogether, these findings point to a role of the SEG in both activating leg CPGs and in coordinating their oscillations, and suggest parallels between the SEG and the brainstem of vertebrates.

Evidence against local neural mechanism for intestinal postprandial hyperemia

1983 ◽  
Vol 245 (3) ◽  
pp. H437-H446 ◽  
Author(s):  
R. A. Nyhof ◽  
C. C. Chou
Keyword(s):  
Oxygen Consumption ◽  
Oleic Acid ◽  
Neural Mechanism ◽  
Jejunal Mucosa ◽  
Vasoactive Substances ◽  
Before And After ◽  
Anesthetized Dogs ◽  
Postprandial Hyperemia

The role of local intestinal nerves in the nutrient-induced intestinal hyperemia was investigated in jejunal segments of anesthetized dogs by comparing the hyperemic effect of intraluminal glucose and oleic acid solutions before and after mucosal anesthesia and infusions of methysergide, hexamethonium, and tetrodotoxin. Methysergide, hexamethonium, and tetrodotoxin all failed to alter either the vascular or metabolic responses to luminal placement of glucose or oleic acid. The increases in blood flow and oxygen uptake produced by glucose or oleic acid, however, were blocked or attenuated after exposing the mucosa to dibucaine. The effect was norepinephrine due to an altered vascular response to vasoactive substances as dibucaine did not alter vascular responses to isoproterenol or norepinephrine. Dibucaine, however, inhibited active transport and increased passive transport of glucose across rat intestinal sacs in vitro. Oxygen consumption of the canine jejunal mucosa was also inhibited by dibucaine in vitro. It seems that inhibition of the nutrient-induced intestinal hyperemia by dibucaine is due, at least in part, to its effect on oxygen consumption and glucose transport of the mucosal epithelial cells. Nutrient-induced hyperemia appears not to be neurally mediated but more closely related to metabolism.

Role of top-down and bottom-up forces on the invasibility of intertidal macroalgal assemblages

2013 ◽  
Vol 76 ◽  
pp. 178-186 ◽  
Author(s):  
Fátima Vaz-Pinto ◽  
Celia Olabarria ◽  
Francisco Arenas
Keyword(s):  
Top Down ◽  
Bottom Up

scholarly journals The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

2007 ◽  
Vol 97 (3) ◽  
pp. 2148-2158 ◽  
Author(s):  
Nathan P. Cramer ◽  
Ying Li ◽  
Asaf Keller
Keyword(s):  
Firing Rate ◽  
Serotonin Receptor ◽  
Central Pattern Generators ◽  
Rhythm Generator ◽  
Low Concentrations ◽  
Rhythmic Firing ◽  
Pattern Generators ◽  
Cortical Inputs

Using the rat vibrissa system, we provide evidence for a novel mechanism for the generation of movement. Like other central pattern generators (CPGs) that underlie many movements, the rhythm generator for whisking can operate without cortical inputs or sensory feedback. However, unlike conventional mammalian CPGs, vibrissa motoneurons (vMNs) actively participate in the rhythmogenesis by converting tonic serotonergic inputs into the patterned motor output responsible for movement of the vibrissae. We find that, in vitro, a serotonin receptor agonist, α-Me-5HT, facilitates a persistent inward current (PIC) and evokes rhythmic firing in vMNs. Within each motoneuron, increasing the concentration of α-Me-5HT significantly increases the both the magnitude of the PIC and the motoneuron's firing rate. Riluzole, which selectively suppresses the Na+ component of PICs at low concentrations, causes a reduction in both of these phenomena. The magnitude of this reduction is directly correlated with the concentration of riluzole. The joint effects of riluzole on PIC magnitude and firing rate in vMNs suggest that the two are causally related. In vivo we find that the tonic activity of putative serotonergic premotoneurons is positively correlated with the frequency of whisking evoked by cortical stimulation. Taken together, these results support the hypothesized novel mammalian mechanism for movement generation in the vibrissa motor system where vMNs actively participate in the rhythmogenesis in response to tonic drive from serotonergic premotoneurons.

scholarly journals Integrating Top-down and Bottom-up Cybersecurity Guidance using XML

2016 ◽  
Author(s):  
Joshua Lubell
Keyword(s):  
Control System ◽  
Potential Application ◽  
Information Sources ◽  
Software Implementation ◽  
Industrial Control System ◽  
Top Down ◽  
Industrial Control ◽  
Bottom Up ◽  
Unauthorized Access ◽  
Security Control

This paper describes a markup-based approach for synthesizing disparate information sources and discusses a software implementation of the approach. The implementation makes it easier for people to use two complementary, but differently structured, guidance specifications together: the (top-down) Cybersecurity Framework and the (bottom-up) National Institute of Standards and Technology Special Publication 800-53 security control catalog. An example scenario demonstrates how the software implementation can help a security professional select the appropriate safeguards for restricting unauthorized access to an Industrial Control System. The implementation and example show the benefits of this approach and suggest its potential application to disciplines other than cybersecurity.

Computational Models of Learning Mechanisms in Psychosis

2017 ◽  
Author(s):  
Andreas Heinz
Keyword(s):  
Mental Disorders ◽  
Psychiatric Disorders ◽  
Computational Models ◽  
The Self ◽  
Psychotic Experiences ◽  
Learning Mechanisms ◽  
Top Down ◽  
Bottom Up ◽  
Surrounding World

Psychotic experiences may best be described as an alteration in the self-ascription of thoughts and actions, which is associated with a profoundly altered experience of oneself and the surrounding world. Computational models of key symptoms of psychiatric disorders are discussed with respect to the attribution of salience and self-relatedness to otherwise irrelevant stimuli and the role of top-down modelling in the generation of delusions. Top-down and bottom-up approaches in understanding mental disorders and their computational models are compared and critically reflected.

The role of the third sector working with the hard and soft structures of public–private partnerships to promote individual health and reinvigorated, healthier communities

2020 ◽  
pp. 301-318
Author(s):  
Tony Chasteauneuf ◽  
Tony Thornton ◽  
Dean Pallant
Keyword(s):  
Health Outcomes ◽  
Local Authority ◽  
Third Sector ◽  
Public Private Partnerships ◽  
Top Down ◽  
Bottom Up ◽  
The Third ◽  
Individual Health ◽  
The Third Sector

This chapter discusses the role of the third sector working with the hard and soft structures of public–private partnerships to promote healthier individuals and communities. It considers how a recommitment to the 'local authority' of citizens and beneficiaries offers the possibility of revitalised and healthier individuals and reinvigorated and healthier communities, which are unachievable through the hard and soft structures of the commissioner/provider statutory approach. The chapter then identifies the pivotal dynamic of one-to-one relationships in these processes and their association with health outcomes (emotional, physical, and spiritual) alongside the opportunities and challenges in agencies engaging/re-engaging with the agency of citizens and beneficiaries. It explores the tension between the 'agency' of citizens and beneficiaries that constitutes bottom-up power and 'agencies' with top-down power. The chapter also looks at the benefits of embracing the expertise and investment of individuals and their communities in their personal and shared lives, how this can be supported and how it can be undermined.

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