scholarly journals The Problem of Adaptation of the Generalized Neural Element

2015 ◽  
Vol 19 (1) ◽  
pp. 69-83 ◽  
Author(s):  
E. V. Konovalov
Keyword(s):  
Neural Element ◽  
Generalized Neural Element

Posterior approach for cervical intramedullary arteriovenous malformation with diffuse-type nidus

1999 ◽  
Vol 91 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Kenji Ohata ◽  
Toshihiro Takami ◽  
Alaa El-Naggar ◽  
Michiharu Morino ◽  
Akimasa Nishio ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Poor Prognosis ◽  
Posterior Approach ◽  
The Other ◽  
Anterior Spinal Artery ◽  
Neural Element ◽  
Feeding Artery ◽  
Diffuse Type ◽  
Content Type ◽  
Fine Print

✓ The treatment of spinal intramedullary arteriovenous malformations (AVMs) with a diffuse-type nidus that contains a neural element poses different challenges compared with a glomus-type nidus. The surgical elimination of such lesions involves the risk of spinal cord ischemia that results from coagulation of the feeding artery that, at the same time, supplies cord parenchyma. However, based on evaluation of the risks involved in performing embolization, together with the frequent occurrence of reperfusion, which necessitates frequent reembolization, the authors consider surgery to be a one-stage solution to a disease that otherwise has a very poor prognosis. Magnetic resonance (MR) imaging revealed diffuse-type intramedullary AVMs in the cervical spinal cords of three patients who subsequently underwent surgery via the posterior approach. The AVM was supplied by the anterior spinal artery in one case and by both the anterior and posterior spinal arteries in the other two cases. In all three cases, a posterior median myelotomy was performed up to the vicinity of the anterior median fissure that divided the spinal cord together with the nidus, and the feeding artery was coagulated and severed at its origin from the anterior spinal artery. In the two cases in which the posterior spinal artery fed the AVM, the feeding artery was coagulated on the dorsal surface of the spinal cord. Neurological outcome improved in one patient and deteriorated slightly to mildly in the other two patients. Postoperative angiography demonstrated complete disappearance of the AVM in all cases. Because of the extremely poor prognosis of patients with spinal intramedullary AVMs, this surgical technique for the treatment of diffuse-type AVMs provides acceptable operative outcome. Surgical intervention should be considered when managing a patient with a diffuse-type intramedullary AVM in the cervical spinal cord.

Functional Inhibition in Direction-Selective Retinal Ganglion Cells: Spatiotemporal Extent and Intralaminar Interactions

2002 ◽  
Vol 88 (2) ◽  
pp. 1026-1039 ◽  
Author(s):  
Steven F. Stasheff ◽  
Richard H. Masland
Keyword(s):  
Ganglion Cells ◽  
Receptive Fields ◽  
Plexiform Layer ◽  
Direction Selectivity ◽  
Inner Plexiform Layer ◽  
Neural Element ◽  
Preferred Direction ◽  
Subsequent Response ◽  
Intermediate Distance ◽  
Excitatory Stimulus

We recorded from on-off direction-selective ganglion cells (DS cells) in the rabbit retina to investigate in detail the inhibition that contributes to direction selectivity in these cells. Using paired stimuli moving sequentially across the cells' receptive fields in the preferred direction, we directly confirmed the prediction of Wyatt and Daw (1975) that a wave of inhibition accompanies any moving excitatory stimulus on its null side, at a fixed spatial offset. Varying the interstimulus distance, stimulus size, luminance, and speed yielded a spatiotemporal map of the strength of inhibition within this region. This “null” inhibition was maximal at an intermediate distance behind a moving stimulus: ½ to 1½ times the width of the receptive field. The strength of inhibition depended more on the distance behind the stimulus than on stimulus speed, and the inhibition often lasted 1–2 s. These spatial and temporal parameters appear to account for the known spatial frequency and velocity tuning of on-off DS cells to drifting contrast gratings. Stimuli that elicit distinct onand off responses to leading and trailing edges revealed that an excitatory response of either polarity could inhibit a subsequent response of either polarity. For example, an offresponse inhibited either an on or off response of a subsequent stimulus. This inhibition apparently is conferred by a neural element or network spanning the on andoff sublayers of the inner plexiform layer, such as a multistratified amacrine cell. Trials using a stationary flashing spot as a probe demonstrated that the total amount of inhibition conferred on the DS cell was equivalent for stimuli moving in either the null or preferred direction. Apparently the cell does not act as a classic “integrate and fire” neuron, summing all inputs at the soma. Rather, computation of stimulus direction likely involves interactions between excitatory and inhibitory inputs in local regions of the dendrites.

Fatigue of the mammalian diaphragm in vitro

1982 ◽  
Vol 53 (2) ◽  
pp. 440-447 ◽  
Author(s):  
S. G. Kelsen ◽  
M. L. Nochomovitz
Keyword(s):  
Duty Cycle ◽  
Phrenic Nerve ◽  
Isometric Tension ◽  
Neural Element ◽  
Sprague Dawley ◽  
Fatigue Process ◽  
Diaphragmatic Muscle ◽  
Diaphragmatic Fatigue ◽  
Diaphragm In Vitro

Diaphragm fatigue was studied in innervated diaphragm strips from 63 Sprague-Dawley rats. The experiments examined 1) the effect on the rate of diaphragmatic fatigue of increases in the diaphragm's duty cycle, i.e., the ratio of the period of diaphragmatic contraction (Ti) to the duration of a cycle of contraction and rest (Ttot) and 2) the possibility that impaired neural transmission contributed to the fatigue process. Alterations in the duty cycle of the diaphragm were simulated by varying the pattern of electrical stimuli applied cyclically to the phrenic nerve. Fatigue was assessed from the rate of fall of isometric tension when the muscle was made to contract 90 times/min. The contribution of neural element fatigue was assessed by comparing the tension during phrenic nerve stimulation to the tension developed when the muscle was stimulated directly. Increasing the duty cycle (Ti/Ttot) from 25 to 50 to 75% increased the rate of diaphragmatic fatigue progressively. Holding Ti/Ttot constant at 75%, while varying Ti and Ttot, did not affect the rate of fatigue. Increases in duty cycle appear to increase the rate of fatigue by increasing the number of times the contractile process was activated. In fatigued muscle strips diaphragmatic tension was greater in directly stimulated muscle than in muscle strips activated via the phrenic nerve. The results indicate that 1) when the breathing action of the diaphragm is simulated in vitro, increases in duty cycle accelerate the fatigue process and 2) failure of transmission of phrenic impulses to diaphragmatic muscle cells contributes to the fall in tension during fatigue.

Design of a Preventive Clearing Blocked System Using PLC Control

2014 ◽  
Vol 556-562 ◽  
pp. 1290-1293
Author(s):  
Xiang Lin Zhang
Keyword(s):  
High Pressure ◽  
Real Time ◽  
Film Coating ◽  
Neural Element ◽  
Bp Network ◽  
Network Training ◽  
Pharmaceutical Tablet ◽  
Rolling Surface ◽  
Key Factor ◽  
Bp Neural Network Model

Film coating machine by way of spraying the coating solution onto the drug is in a continuous rolling surface. The tablet tends to produce tape smaller even if the spray flow blockage. Then the tablet will crack due to high temperature. Therefore, pharmaceutical tablet coating spray flow rate is a key factor affecting the quality. This article first proposes preventive clearing blocked in the pipeline but not blocking the upcoming clogged. Air purge starts immediately. PLC real-time acquisition is carried out by the pressure at both ends of the pipeline, the pipeline flow liquid contents, when the pressure is detected. The flow reaches a critical point obtained by BP network training, immediately starting the high-pressure air purge. The value of real-time detection uses PLC gun pipeline pressure, flow, etc. It combined weights of the neural element BP neural network model that was trained by the PLC programming. Gun pipe blockage and promptly started high pressure alarm air purge, preventive clearing blocked. Experiments show that preventive clearing blocked pipe blockage can promptly remove the gun.

scholarly journals A common neural element receiving rhythmic arm and leg activity as assessed by reflex modulation in arm muscles

2016 ◽  
Vol 115 (4) ◽  
pp. 2065-2075 ◽  
Author(s):  
Syusaku Sasada ◽  
Toshiki Tazoe ◽  
Tsuyoshi Nakajima ◽  
Genki Futatsubashi ◽  
Hiroyuki Ohtsuka ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Motor Evoked Potentials ◽  
Cervical Spinal Cord ◽  
Voluntary Contraction ◽  
Reflex Modulation ◽  
Neural Element ◽  
Single Motor Unit ◽  
Arm Cycling ◽  
Leg Cycling ◽  
Arm Muscles

Neural interactions between regulatory systems for rhythmic arm and leg movements are an intriguing issue in locomotor neuroscience. Amplitudes of early latency cutaneous reflexes (ELCRs) in stationary arm muscles are modulated during rhythmic leg or arm cycling but not during limb positioning or voluntary contraction. This suggests that interneurons mediating ELCRs to arm muscles integrate outputs from neural systems controlling rhythmic limb movements. Alternatively, outputs could be integrated at the motoneuron and/or supraspinal levels. We examined whether a separate effect on the ELCR pathways and cortico-motoneuronal excitability during arm and leg cycling is integrated by neural elements common to the lumbo-sacral and cervical spinal cord. The subjects performed bilateral leg cycling (LEG), contralateral arm cycling (ARM), and simultaneous contralateral arm and bilateral leg cycling (A&L), while ELCRs in the wrist flexor and shoulder flexor muscles were evoked by superficial radial (SR) nerve stimulation. ELCR amplitudes were facilitated by cycling tasks and were larger during A&L than during ARM and LEG. A low stimulus intensity during ARM or LEG generated a larger ELCR during A&L than the sum of ELCRs during ARM and LEG. We confirmed this nonlinear increase in single motor unit firing probability following SR nerve stimulation during A&L. Furthermore, motor-evoked potentials following transcranial magnetic and electrical stimulation did not show nonlinear potentiation during A&L. These findings suggest the existence of a common neural element of the ELCR reflex pathway that is active only during rhythmic arm and leg movement and receives convergent input from contralateral arms and legs.

scholarly journals Model of a bilateral Brown-type central pattern generator for symmetric and asymmetric locomotion

2018 ◽  
Vol 119 (3) ◽  
pp. 1071-1083 ◽  
Author(s):  
Anton Sobinov ◽  
Sergiy Yakovenko
Keyword(s):  
Analytical Solution ◽  
Central Pattern Generators ◽  
Analytical Description ◽  
Numerical Approach ◽  
Pattern Generation ◽  
Neural Element ◽  
Steering Control ◽  
Velocity Signal ◽  
Robust Model ◽  
Order Of Magnitude

The coordinated activity of muscles is produced in part by spinal rhythmogenic neural circuits, termed central pattern generators (CPGs). A classical CPG model is a system of coupled oscillators that transform locomotor drive into coordinated and gait-specific patterns of muscle recruitment. The network properties of this conceptual model can be simulated by a system of ordinary differential equations with a physiologically inspired coupling locus of interactions capturing the timing relationship for bilateral coordination of limbs in locomotion. Whereas most similar models are solved numerically, it is intriguing to have a full analytical description of this plausible CPG architecture to illuminate the functionality within this structure and to expand it to include steering control. Here, we provided a closed-form analytical solution contrasted against the previous numerical method. The evaluation time of the analytical solution was decreased by an order of magnitude when compared with the numerical approach (relative errors, <0.01%). The analytical solution tested and supported the previous finding that the input to the model can be expressed in units of the desired limb locomotor speed. Furthermore, we performed parametric sensitivity analysis in the context of controlling steering and documented two possible mechanisms associated with either an external drive or intrinsic CPG parameters. The results identify specific propriospinal pathways that may be associated with adaptations within the CPG structure. The model offered several network configurations that may generate the same behavioral outcomes. NEW & NOTEWORTHY Using a simple process of leaky integration, we developed an analytical solution to a robust model of spinal pattern generation. We analyzed the ability of this neural element to exert locomotor control of the signal associated with limb speeds and tested the ability of this simple structure to embed steering control using the velocity signal in the model’s inputs or within the internal connectivity of its elements.

Computational Aspects of the Respiratory Pattern Generator

1994 ◽  
Vol 6 (1) ◽  
pp. 56-68 ◽  
Author(s):  
Allan Gottschalk ◽  
Malcolm D. Ogilvie ◽  
Diethelm W. Richter ◽  
Allan I. Pack
Keyword(s):  
Network Model ◽  
Time Constant ◽  
Respiratory Rhythm ◽  
Network Connectivity ◽  
Pattern Generator ◽  
Continuous Variable ◽  
Respiratory Pattern ◽  
Neural Element ◽  
Respiratory Rhythmogenesis ◽  
Computational Aspects

To help evaluate the hypothesis that the central respiratory rhythm is generated by a network of interacting neurons, a network model of respiratory rhythmogenesis is formulated and examined computationally. The neural elements of the network are driven by tonic inputs and generate a continuous variable representing firing rate. Each neural element in the model can be described by an activation time constant, an adaptation time constant, and a step nonlinearity. Initial network connectivity was based on an earlier proposed model of the central respiratory pattern generator. These connections were adjusted interactively until the model trajectories resembled those observed electrophysiologically. The properties of the resulting network were examined computationally by simulation, determination of the phase resetting behavior of the network oscillator, and examination of the localized eigenstructure of the network. These results demonstrate that the network model can account for a number of diverse physiological observations, and, thus, support the network hypothesis of respiratory rhymogenesis.

Neurogenic expression of snail is controlled by separable CNS and PNS promoter elements

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 199-207 ◽  
Author(s):  
Y.T. Ip ◽  
M. Levine ◽  
E. Bier
Keyword(s):  
Regulatory Region ◽  
Neural Element ◽  
Proneural Gene ◽  
Lacz Expression ◽  
Proneural Genes ◽  
Growing Body ◽  
Mesoderm Formation ◽  
Separate Control ◽  
Early Neurogenesis ◽  
Developing Nervous System

The Drosophila snail (sna) gene is first expressed in cells giving rise to mesoderm and is required for mesoderm formation. sna is subsequently expressed in the developing nervous system. sna expression during neurogenesis evolves from segmentally repeated neuroectodermal domains to a pan-neural pattern. We have identified a 2.8 kb regulatory region of the sna promoter that drives LacZ expression in a faithful neuronal pattern. Deletion analysis of this region indicates that the pan-neural element is composed of separable CNS and PNS components. This finding is unexpected since all known genes controlling early neurogenesis, including the proneural genes (i.e. da and AS-C), are expressed in both the CNS and PNS. We also show that expression of sna during neurogenesis is largely independent of the proneural genes da and AS-C. The separate control of CNS and PNS sna expression and independence of proneural gene regulation add to a growing body of evidence that current genetic models of neurogenesis are substantially incomplete.

Sign in / Sign up

Export Citation Format

Share Document