Wipe and flexion reflexes of the frog. I. Kinematics and EMG patterns

1993 ◽  
Vol 69 (5) ◽  
pp. 1725-1735 ◽  
Author(s):  
J. L. Schotland ◽  
W. Z. Rymer
Keyword(s):  
Neural Control ◽  
Neural Circuits ◽  
Neural Circuit ◽  
Activity Patterns ◽  
Three Dimensional ◽  
Building Blocks ◽  
Lateral Position ◽  
Movement Trajectories ◽  
Ankle Joints ◽  
Emg Patterns

1. We evaluated the hypothesis that the neural control of complex motor behaviors is simplified by building movement sequences from a series of simple neural "building blocks." In particular, we compared two reflex behaviors of the frog, flexion withdrawal and the hindlimb-hindlimb wipe reflex, to determine whether a single neural circuit that coordinates flexion withdrawal is incorporated as the first element in a sequence of neural circuits comprising the wipe. The neural organization of these two reflexes was compared using a quantitative analysis of movement kinematics and muscle activity patterns [electromyograms (EMGs)]. 2. The three-dimensional coordinates of the position of the foot over time and the angular excursion of hip, knee, and ankle joints were recorded using a WATSMART infrared emitter-detector system. These data were quantified using principal-components analysis to provide a measure of the shape (eigenvalues) and orientation (eigen-vector coefficients) of the movement trajectories. The latencies and magnitudes of EMGs of seven muscles acting at the hip, knee, and ankle were analyzed over the interval from EMG onset to movement onset, and EMG magnitudes during the initial flexion of the limb. These variables were compared during flexion withdrawal and the initial flexion movement of the limb during the hindlimb-hindlimb wipe reflex (before the onset of the frequently rhythmic portion when the stimulus is removed) when the two reflexes were elicited from comparable stimulus locations. 3. In both the flexion reflex and the initial movement segment of the wipe reflex, the foot moves along a relatively straight line. However, the foot is directed to a more rostral and lateral position during flexion than during wipe. All three joints flex during flexion withdrawal, whereas during the wipe, the knee and ankle joints flex but the angular excursion of the hip joint may vary. The different orientations of the movement trajectories are associated with EMG patterns that differ in both timing and magnitude between the two reflexes. 4. The differences in the kinematics and EMG patterns of the two reflexes during unrestrained movements make it unlikely that the neural circuit that coordinates flexion withdrawal is incorporated as the first element in the sequence of neural circuits underlying the wipe reflex. 5. Unlike the wipe reflex, during flexion withdrawal there is no apparent constraint on the accuracy of placement at the end of the movement, yet the animals nevertheless achieved consistent final positions of both the foot and of each joint. The implications of these findings with respect to the controlled variables are discussed.

scholarly journals Neural control of behavioural choice in juvenile crayfish

2010 ◽  
Vol 277 (1699) ◽  
pp. 3493-3500 ◽  
Author(s):  
William H. Liden ◽  
Mary L. Phillips ◽  
Jens Herberholz
Keyword(s):  
Natural Selection ◽  
Empirical Evidence ◽  
Neural Control ◽  
Food Source ◽  
Neural Circuits ◽  
Neural Circuit ◽  
Costs And Benefits ◽  
Activation Patterns ◽  
Neuronal Mechanisms ◽  
Slow Moving

Natural selection leads to behavioural choices that increase the animal's fitness. The neuronal mechanisms underlying behavioural choice are still elusive and empirical evidence connecting neural circuit activation to adaptive behavioural output is sparse. We exposed foraging juvenile crayfish to approaching shadows of different velocities and found that slow-moving shadows predominantly activated a pair of giant interneurons, which mediate tail-flips that thrust the animals backwards and away from the approaching threat. Tail-flips also moved the animals farther away from an expected food source, and crayfish defaulted to freezing behaviour when faced with fast-approaching shadows. Under these conditions, tail-flipping, an ineffective and costly escape strategy was suppressed in favour of freezing, a more beneficial choice. The decision to freeze also dominated in the presence of a more desirable resource; however, the increased incentive was less effective in suppressing tail-flipping when paired with slow-moving visual stimuli that reliably evoked tail-flips in most animals. Together this suggests that crayfish make value-based decisions by weighing the costs and benefits of different behavioural options, and they select adaptive behavioural output based on the activation patterns of identifiable neural circuits.

scholarly journals Understanding neural circuit development through theory and models

2017 ◽  
Author(s):  
Leonidas M. A. Richter ◽  
Julijana Gjorgjieva
Keyword(s):  
Quantitative Methods ◽  
Computational Models ◽  
Neural Circuits ◽  
Neural Circuit ◽  
Activity Patterns ◽  
Data Sets ◽  
Topographic Map ◽  
Theoretical And Computational Models ◽  
Classical Models ◽  
Sets Theory

AbstractHow are neural circuits organized and tuned to achieve stable function and produce robust behavior? The organization process begins early in development and involves a diversity of mechanisms unique to this period. We summarize recent progress in theoretical neuroscience that has substantially contributed to our understanding of development at the single neuron, synaptic and network level. We go beyond classical models of topographic map formation, and focus on the generation of complex spatiotemporal activity patterns, their role in refinements of particular circuit features, and the emergence of functional computations. Aided by the development of novel quantitative methods for data analysis, theoretical and computational models have enabled us to test the adequacy of specific assumptions, explain experimental data and propose testable hypotheses. With the accumulation of larger data sets, theory and models will likely play an even more important role in understanding the development of neural circuits.

Adductors, abductors, and the evolution of archosaur locomotion

Paleobiology ◽  
2000 ◽  
Vol 26 (4) ◽  
pp. 734-751 ◽  
Author(s):  
John R. Hutchinson ◽  
Stephen M. Gatesy
Keyword(s):  
Hip Joint ◽  
Neural Control ◽  
Activity Patterns ◽  
Three Dimensional ◽  
Dimensional Control ◽  
Hip Morphology ◽  
Phylogenetic Perspective ◽  
Axis Rotation ◽  
And Function ◽  
Stepwise Evolution

Living crocodilians (Crocodylia) and birds (Neornithes) differ in many aspects of hindlimb anatomy and locomotor function. How did this disparity evolve? We integrate information from fossils with functional descriptions of locomotion in living crocodilians and birds, using a phylogenetic perspective. We then outline the major changes in three-dimensional control of the hip joint along the line from the ancestral archosaur to birds. Our analysis reveals that most aspects of hip morphology and function in Alligator are ancestral for Archosauria. Femoral protractors and retractors are located cranial and caudal to the hip, respectively. Similarly, femoral adductors and abductors are located ventral and dorsal to the hip. Transformations of this ancestral pattern on the line to birds involved modifications in osteology, myology, and neural control. In some cases, homologous muscles changed function by acquiring new activity patterns. In others, activity was conserved, but origins and/or insertions were altered. Fossil theropods document the stepwise evolution of a novel mechanism of limb adduction/abduction involving long-axis rotation of the femur. This mechanism accounts for the conspicuous absence of significant musculature ventral and dorsal to the hip joint in extant birds.

Predicting spatial activity patterns in a neural map from a probabilistic atlas of 3-D reconstructed neurons

1995 ◽  
Vol 53 ◽  
pp. 812-813
Author(s):  
G. Jacobs ◽  
F. Theunissen
Keyword(s):  
Activity Patterns ◽  
Three Dimensional ◽  
Sensory System ◽  
Neural System ◽  
Probabilistic Atlas ◽  
Uniform Sample ◽  
Dimensional Reconstruction ◽  
The Time Domain ◽  
And Function ◽  
Visualization Techniques

In order to understand how the algorithms underlying neural computation are implemented within any neural system, it is necessary to understand details of the anatomy, physiology and global organization of the neurons from which the system is constructed. Information is represented in neural systems by patterns of activity that vary in both their spatial extent and in the time domain. One of the great challenges to microscopists is to devise methods for imaging these patterns of activity and to correlate them with the underlying neuroanatomy and physiology. We have addressed this problem by using a combination of three dimensional reconstruction techniques, quantitative analysis and computer visualization techniques to build a probabilistic atlas of a neural map in an insect sensory system. The principal goal of this study was to derive a quantitative representation of the map, based on a uniform sample of afferents that was of sufficient size to allow statistically meaningful analyses of the relationships between structure and function.

scholarly journals Lath Martensite Microstructure Modeling: A High-Resolution Crystal Plasticity Simulation Study

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 691
Author(s):  
Francisco-José Gallardo-Basile ◽  
Yannick Naunheim ◽  
Franz Roters ◽  
Martin Diehl
Keyword(s):  
High Resolution ◽  
Mechanical Behavior ◽  
Crystal Plasticity ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Building Blocks ◽  
Quantitative Agreement ◽  
Carbon Steels ◽  
Plastic Behavior ◽  
Austenitic Phase

Lath martensite is a complex hierarchical compound structure that forms during rapid cooling of carbon steels from the austenitic phase. At the smallest, i.e., ‘single crystal’ scale, individual, elongated domains, form the elemental microstructural building blocks: the name-giving laths. Several laths of nearly identical crystallographic orientation are grouped together to blocks, in which–depending on the exact material characteristics–clearly distinguishable subblocks might be observed. Several blocks with the same habit plane together form a packet of which typically three to four together finally make up the former parent austenitic grain. Here, a fully parametrized approach is presented which converts an austenitic polycrystal representation into martensitic microstructures incorporating all these details. Two-dimensional (2D) and three-dimensional (3D) Representative Volume Elements (RVEs) are generated based on prior austenite microstructure reconstructed from a 2D experimental martensitic microstructure. The RVEs are used for high-resolution crystal plasticity simulations with a fast spectral method-based solver and a phenomenological constitutive description. The comparison of the results obtained from the 2D experimental microstructure and the 2D RVEs reveals a high quantitative agreement. The stress and strain distributions and their characteristics change significantly if 3D microstructures are used. Further simulations are conducted to systematically investigate the influence of microstructural parameters, such as lath aspect ratio, lath volume, subblock thickness, orientation scatter, and prior austenitic grain shape on the global and local mechanical behavior. These microstructural features happen to change the local mechanical behavior, whereas the average stress–strain response is not significantly altered. Correlations between the microstructure and the plastic behavior are established.

Design and Optimization of a Shape Memory Alloy-Based Self-Folding Sheet

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Edwin Peraza-Hernandez ◽  
Darren Hartl ◽  
Edgar Galvan ◽  
Richard Malak
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Building Blocks ◽  
Passive Layer ◽  
Von Mises Stress ◽  
Maximum Temperature ◽  
Radius Of Curvature ◽  
Folding Angle ◽  
The Impact

Origami engineering—the practice of creating useful three-dimensional structures through folding and fold-like operations on two-dimensional building-blocks—has the potential to impact several areas of design and manufacturing. In this article, we study a new concept for a self-folding system. It consists of an active, self-morphing laminate that includes two meshes of thermally-actuated shape memory alloy (SMA) wire separated by a compliant passive layer. The goal of this article is to analyze the folding behavior and examine key engineering tradeoffs associated with the proposed system. We consider the impact of several design variables including mesh wire thickness, mesh wire spacing, thickness of the insulating elastomer layer, and heating power. Response parameters of interest include effective folding angle, maximum von Mises stress in the SMA, maximum temperature in the SMA, maximum temperature in the elastomer, and radius of curvature at the fold line. We identify an optimized physical realization for maximizing folding capability under mechanical and thermal failure constraints. Furthermore, we conclude that the proposed self-folding system is capable of achieving folds of significant magnitude (as measured by the effective folding angle) as required to create useful 3D structures.

A new three-dimensional anionic cadmium(II) dicyanamide network

2014 ◽  
Vol 70 (11) ◽  
pp. 1054-1056 ◽  
Author(s):  
Qiang Li ◽  
Hui-Ting Wang
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Unit Cell Volume ◽  
Three Dimensional ◽  
Building Blocks ◽  
The Other ◽  
Dimensional Structure ◽  
Cadmium Nitrate ◽  
Nitrate Tetrahydrate ◽  
Anionic Framework

A new cadmium dicyanamide complex, poly[tetramethylphosphonium [μ-chlorido-di-μ-dicyanamido-κ4N1:N5-cadmium(II)]], [(CH3)4P][Cd(NCNCN)2Cl], was synthesized by the reaction of tetramethylphosphonium chloride, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each CdIIatom is octahedrally coordinated by four terminal N atoms from four anionic dicyanamide (dca) ligands and by two chloride ligands. The dicyanamide ligands play two different roles in the building up of the structure; one role results in the formation of [Cd(dca)Cl]2building blocks, while the other links the building blocks into a three-dimensional structure. The anionic framework exhibits a solvent-accessible void of 673.8 Å3, amounting to 47.44% of the total unit-cell volume. The cavities in the network are occupied by pairs of tetramethylphosphonium cations.

scholarly journals Assembly of multicomponent structures from hundreds of micron-scale building blocks using optical tweezers

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jeffrey E. Melzer ◽  
Euan McLeod
Keyword(s):  
Optical Tweezers ◽  
Three Dimensional ◽  
Building Blocks ◽  
Optical Tweezer ◽  
Device Fabrication ◽  
Positional Accuracy ◽  
Component Structure ◽  
Material Development ◽  
Critical Process Parameters ◽  
Optical Positioning

AbstractThe fabrication of three-dimensional (3D) microscale structures is critical for many applications, including strong and lightweight material development, medical device fabrication, microrobotics, and photonic applications. While 3D microfabrication has seen progress over the past decades, complex multicomponent integration with small or hierarchical feature sizes is still a challenge. In this study, an optical positioning and linking (OPAL) platform based on optical tweezers is used to precisely fabricate 3D microstructures from two types of micron-scale building blocks linked by biochemical interactions. A computer-controlled interface with rapid on-the-fly automated recalibration routines maintains accuracy even after placing many building blocks. OPAL achieves a 60-nm positional accuracy by optimizing the molecular functionalization and laser power. A two-component structure consisting of 448 1-µm building blocks is assembled, representing the largest number of building blocks used to date in 3D optical tweezer microassembly. Although optical tweezers have previously been used for microfabrication, those results were generally restricted to single-material structures composed of a relatively small number of larger-sized building blocks, with little discussion of critical process parameters. It is anticipated that OPAL will enable the assembly, augmentation, and repair of microstructures composed of specialty micro/nanomaterial building blocks to be used in new photonic, microfluidic, and biomedical devices.

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