scholarly journals ADrosophilalarval premotor/motor neuron connectome generating two behaviors via distinct spatio-temporal muscle activity

2019 ◽  
Author(s):  
Aref Arzan Zarin ◽  
Brandon Mark ◽  
Albert Cardona ◽  
Ashok Litwin-Kumar ◽  
Chris Q. Doe
Keyword(s):  
Motor Neurons ◽  
Muscle Activity ◽  
Recurrent Network ◽  
The Body ◽  
Temporal Muscle ◽  
Motor Circuits ◽  
Premotor Neurons ◽  
Spatio Temporal ◽  
Locomotor Behaviors

AbstractAnimals generate diverse motor behaviors, yet how the same motor neurons generate distinct behaviors remains an open question.Drosophilalarvae have multiple behaviors – e.g. forward crawling, backward crawling, self-righting and escape – and all of the body wall motor neurons (MNs) driving these behaviors have been identified. Despite impressive progress in mapping larval motor circuits, the role of most motor neurons in locomotion remains untested, the majority of premotor neurons (PMNs) remain to be identified, and a full understanding of proprioceptor-PMN-MN connectivity is missing. Here we report a comprehensive larval proprioceptor-PMN-MN connectome; describe individual muscle/MN phase activity during both forward and backward locomotor behaviors; identify PMN-MN connectivity motifs that could generate muscle activity phase relationships, plus selected experimental validation; identify proprioceptor-PMN connectivity that provides an anatomical explanation for the role of proprioception in promoting locomotor velocity; and identify a new candidate escape motor circuit. Finally, we generate a recurrent network model that produces the observed sequence of motor activity, showing that the identified pool of premotor neurons is sufficient to generate two distinct larval behaviors. We conclude that different locomotor behaviors can be generated by a specific group of premotor neurons generating behavior-specific motor rhythms.

scholarly journals A multilayer circuit architecture for the generation of distinct locomotor behaviors in Drosophila

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Aref Arzan Zarin ◽  
Brandon Mark ◽  
Albert Cardona ◽  
Ashok Litwin-Kumar ◽  
Chris Q Doe
Keyword(s):  
Motor Neurons ◽  
Activity Patterns ◽  
Recurrent Network ◽  
Neuronal Morphology ◽  
Motor Behaviors ◽  
Motor Circuits ◽  
Model Predictions ◽  
Premotor Neurons ◽  
Locomotor Behaviors ◽  
Open Question

Animals generate diverse motor behaviors, yet how the same motor neurons (MNs) generate two distinct or antagonistic behaviors remains an open question. Here, we characterize Drosophila larval muscle activity patterns and premotor/motor circuits to understand how they generate forward and backward locomotion. We show that all body wall MNs are activated during both behaviors, but a subset of MNs change recruitment timing for each behavior. We used TEM to reconstruct a full segment of all 60 MNs and 236 premotor neurons (PMNs), including differentially-recruited MNs. Analysis of this comprehensive connectome identified PMN-MN ‘labeled line’ connectivity; PMN-MN combinatorial connectivity; asymmetric neuronal morphology; and PMN-MN circuit motifs that could all contribute to generating distinct behaviors. We generated a recurrent network model that reproduced the observed behaviors, and used functional optogenetics to validate selected model predictions. This PMN-MN connectome will provide a foundation for analyzing the full suite of larval behaviors.

scholarly journals Anatomy and Neural Pathways Modulating Distinct Locomotor Behaviors in Drosophila Larva

Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 90
Author(s):  
Swetha B. M. Gowda ◽  
Safa Salim ◽  
Farhan Mohammad
Keyword(s):  
Motor Neurons ◽  
Model Systems ◽  
Neural Pathways ◽  
Animal Movements ◽  
Drosophila Larvae ◽  
The Central Nervous System ◽  
Drosophila Larva ◽  
Locomotor Behaviors ◽  
Basic Level

The control of movements is a fundamental feature shared by all animals. At the most basic level, simple movements are generated by coordinated neural activity and muscle contraction patterns that are controlled by the central nervous system. How behavioral responses to various sensory inputs are processed and integrated by the downstream neural network to produce flexible and adaptive behaviors remains an intense area of investigation in many laboratories. Due to recent advances in experimental techniques, many fundamental neural pathways underlying animal movements have now been elucidated. For example, while the role of motor neurons in locomotion has been studied in great detail, the roles of interneurons in animal movements in both basic and noxious environments have only recently been realized. However, the genetic and transmitter identities of many of these interneurons remains unclear. In this review, we provide an overview of the underlying circuitry and neural pathways required by Drosophila larvae to produce successful movements. By improving our understanding of locomotor circuitry in model systems such as Drosophila, we will have a better understanding of how neural circuits in organisms with different bodies and brains lead to distinct locomotion types at the organism level. The understanding of genetic and physiological components of these movements types also provides directions to understand movements in higher organisms.

MATHEMATICAL MODELLING OF CANCER CELL INVASION OF TISSUE: THE ROLE OF THE UROKINASE PLASMINOGEN ACTIVATION SYSTEM

2005 ◽  
Vol 15 (11) ◽  
pp. 1685-1734 ◽  
Author(s):  
M. A. J. CHAPLAIN ◽  
G. LOLAS
Keyword(s):  
Cancer Cells ◽  
Cancer Cell ◽  
Cell Invasion ◽  
The Body ◽  
Plasminogen Activation ◽  
Cancer Cell Invasion ◽  
Plasminogen Activation System ◽  
Activation System ◽  
Spatio Temporal

The growth of solid tumours proceeds through two distinct phases: the avascular and the vascular phase. It is during the latter stage that the insidious process of cancer invasion of peritumoral tissue can and does take place. Vascular tumours grow rapidly allowing the cancer cells to establish a new colony in distant organs, a process that is known as metastasis. The progression from a single, primary tumour to multiple tumours in distant sites throughout the body is known as the metastatic cascade. This is a multistep process that first involves the over-expression by the cancer cells of proteolytic enzyme activity, such as the urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs). uPA itself initiates the activation of an enzymatic cascade that primarily involves the activation of plasminogen and subsequently its matrix degrading protein plasmin. Degradation of the matrix then enables the cancer cells to migrate through the tissue and subsequently to spread to secondary sites in the body. In this paper we consider a mathematical model of cancer cell invasion of tissue (extracellular matrix) which focuses on the role of the plasminogen activation system. The model consists of a system of reaction-diffusion-taxis partial differential equations describing the interactions between cancer cells, urokinase plasminogen activator (uPA), uPA inhibitors, plasmin and the host tissue. The focus of the modelling is on the spatio-temporal dynamics of the uPA system and how this influences the migratory properties of the cancer cells through random motility, chemotaxis and haptotaxis. The results obtained from numerical computations carried out on the model equations produce rich, dynamic heterogeneous spatio-temporal solutions and demonstrate the ability of rather simple models to produce complicated dynamics, all of which are associated with tumour heterogeneity and cancer cell progression and invasion.

Kinematic and Electromyographic Analysis of the functional role of the body axis during Terrestrial and Aquatic Locomotion in the Salamander Ambystoma Tigrinum

1992 ◽  
Vol 162 (1) ◽  
pp. 107-130 ◽  
Author(s):  
LARRY M. FROLICH ◽  
ANDREW A. BIEWENER
Keyword(s):  
Muscle Activity ◽  
Functional Role ◽  
The Body ◽  
Ambystoma Tigrinum ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Wave Patterns ◽  
Axial Morphology ◽  
Electromyographic Analysis

Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs -- one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during theoriginal evolution of terrestriality in early tetrapods.

Mechanics of the fast-start: muscle function and the role of intramuscular pressure in the escape behavior of amia calva and polypterus palmas

1998 ◽  
Vol 201 (22) ◽  
pp. 3041-3055 ◽  
Author(s):  
MW Westneat ◽  
ME Hale ◽  
MJ Mchenry ◽  
JH Long
Keyword(s):  
Muscle Activity ◽  
Escape Response ◽  
Muscle Force ◽  
Escape Behavior ◽  
Pressure Change ◽  
The Body ◽  
Intramuscular Pressure ◽  
Fast Start ◽  
Amia Calva

The fast-start escape response is a rapid, powerful body motion used to generate high accelerations of the body in virtually all fishes. Although the neurobiology and behavior of the fast-start are often studied, the patterns of muscle activity and muscle force production during escape are less well understood. We studied the fast-starts of two basal actinopterygian fishes (Amia calva and Polypterus palmas) to investigate the functional morphology of the fast-start and the role of intramuscular pressure (IMP) in escape behavior. Our goals were to determine whether IMP increases during fast starts, to look for associations between muscle activity and elevated IMP, and to determine the functional role of IMP in the mechanics of the escape response. We simultaneously recorded the kinematics, muscle activity patterns and IMP of four A. calva and three P. palmas during the escape response. Both species generated high IMPs of up to 90 kPa (nearly 1 atmosphere) above ambient during the fast-start. The two species showed similar pressure magnitudes but had significantly different motor patterns and escape performance. Stage 1 of the fast-start was generated by simultaneous contraction of locomotor muscle on both sides of the body, although electromyogram amplitudes on the contralateral (convex) side of the fish were significantly lower than on the ipsilateral (concave) side. Simultaneous recordings of IMP, escape motion and muscle activity suggest that pressure change is caused by the contraction and radial swelling of cone-shaped myomeres. We develop a model of IMP production that incorporates myomere geometry, the concept of constant-volume muscular hydrostats, the relationship between fiber angle and muscle force, and the forces that muscle fibers produce. The timing profile of pressure change, behavior and muscle action indicates that elevated muscle pressure is a mechanism of stiffening the body and functions in force transmission during the escape response.

scholarly journals Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control

2019 ◽  
Author(s):  
Rebecca A. Callahan ◽  
Richard Roberts ◽  
Mohini Sengupta ◽  
Yukiko Kimura ◽  
Shin-ichi Higashijima ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Speed Control ◽  
Morphological Properties ◽  
Larval Zebrafish ◽  
Motor Circuits ◽  
Transgenic Lines ◽  
Left And Right ◽  
Specific Influence

AbstractThe spinal cord contains a diverse array of interneurons that govern motor output. Traditionally, models of spinal circuits have emphasized the role of inhibition in enforcing reciprocal alternation between left and right sides or flexors and extensors. However, recent work has shown that inhibition also increases coincident with excitation during contraction. Here, using larval zebrafish, we investigate the V2b (Gata3+) class of neurons, which contribute to flexor-extensor alternation but are otherwise poorly understood. Using newly generated transgenic lines we define two stable subclasses with distinct neurotransmitter and morphological properties. These two V2b subclasses make direct synapses onto motor neurons with differential targeting to slower and faster circuits. In vivo, optogenetic suppression of V2b activity leads to increases in locomotor speed. We conclude that V2b neurons exert speed-specific influence over axial motor circuits throughout the rostrocaudal axis. Together, these results indicate a new role for ipsilateral inhibition in speed control.

scholarly journals Approaches to the World

2021 ◽  
Author(s):  
Gesa Lindemann
Keyword(s):  
Social Order ◽  
Temporal Order ◽  
The Body ◽  
Spatial Turn ◽  
Linguistic Turn ◽  
Highly Sensitive ◽  
The Social ◽  
Material Turn ◽  
Spatio Temporal

Responding to the critique of methodological ethnocentrism, Lindemann develops a new general social theory that is also highly sensitive to socio-cultural differences. Drawing on Helmuth Plessner’s theory of excentric positionality, social order is understood as a symbolically and technically mediated spatio-temporal order that is integrated by an order of violence. Lindemann hereby brings together three significant aspects of recent debates: the debates on the necessity of a theoretical turn (such as the linguistic turn, the material turn, the body turn, the pictorial turn and the spatial turn); second, the debates on the actor status of non-humans and the borders of the social world, and third, the discussions about the role of violence in structuring social processes.

Three forms of the scratch reflex in the spinal turtle: central generation of motor patterns

1985 ◽  
Vol 53 (6) ◽  
pp. 1517-1534 ◽  
Author(s):  
G. A. Robertson ◽  
L. I. Mortin ◽  
J. Keifer ◽  
P. S. Stein
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Neuromuscular Blockade ◽  
Motor Neurons ◽  
Muscle Activity ◽  
Activity Patterns ◽  
Knee Extensor ◽  
The Body ◽  
Retractor Muscle ◽  
Neuron Activity

A turtle with a complete transection of the spinal cord, termed a spinal turtle, exhibits three types or “forms” of the scratch reflex: the rostral scratch, pocket scratch, and caudal scratch (21). Each scratch form is elicited by tactile stimulation of a site on the body surface innervated by afferents entering the spinal cord caudal to the transection. We recorded electromyographic (EMG) potentials from the hindlimb during each of the three forms of the scratch in the spinal turtle (see Fig. 1). Common to all scratch forms is the rhythmic alternation of the activity of the hip protractor muscle (VP-HP) and hip retractor muscle (HR-KF). Each form of the scratch displays a characteristic timing of the activity of the knee extensor muscle (FT-KE) with respect to the cycle of activity of the hip muscles VP-HP and HR-KF. In a rostral scratch, activation of FT-KE occurs during the latter portion of VP-HP activation. In a pocket scratch, activation of FT-KE occurs during HR-KF activation. In a caudal scratch, activation of FT-KE occurs after the cessation of HR-KF activation. The timing characteristics of these muscle activity patterns correspond to the timing characteristics of changes in the angles of the knee joint and the hip joint obtained with movement analyses (21). We recorded electroneurographic (ENG) potentials from peripheral nerves of the hindlimb during each of the three forms of the “fictive” scratch in the spinal turtle immobilized with neuromuscular blockade (see Fig. 4). Common to all forms of the fictive scratch is the rhythmic alternation of the activity of hip protractor motor neurons (VP-HP) and hip retractor motor neurons (HR-KF). Each form displays a characteristic timing of the activity of knee extensor motor neurons (FT-KE) with respect to the cycle of VP-HP and HR-KF motor neuron activity. The timing characteristics of these motor neuron activity patterns are similar to the timing characteristics of the muscle activity patterns obtained in the preparation with movement (cf. Figs. 1 and 4). The motor pattern for each scratch form is generated centrally within the spinal cord. In the spinal immobilized preparation, neuromuscular blockade prevents both limb movement and phasic sensory input, and complete spinal transection isolates the cord from supraspinal input.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Rebecca A Callahan ◽  
Richard Roberts ◽  
Mohini Sengupta ◽  
Yukiko Kimura ◽  
Shin-ichi Higashijima ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Speed Control ◽  
Morphological Properties ◽  
Larval Zebrafish ◽  
Motor Circuits ◽  
Transgenic Lines ◽  
Left And Right

The spinal cord contains a diverse array of interneurons that govern motor output. Traditionally, models of spinal circuits have emphasized the role of inhibition in enforcing reciprocal alternation between left and right sides or flexors and extensors. However, recent work has shown that inhibition also increases coincident with excitation during contraction. Here, using larval zebrafish, we investigate the V2b (Gata3+) class of neurons, which contribute to flexor-extensor alternation but are otherwise poorly understood. Using newly generated transgenic lines we define two stable subclasses with distinct neurotransmitter and morphological properties. These V2b subclasses synapse directly onto motor neurons with differential targeting to speed-specific circuits. In vivo, optogenetic manipulation of V2b activity modulates locomotor frequency: suppressing V2b neurons elicits faster locomotion, whereas activating V2b neurons slows locomotion. We conclude that V2b neurons serve as a brake on axial motor circuits. Together, these results indicate a role for ipsilateral inhibition in speed control.

scholarly journals A single neuron subset governs a single coactive neuron circuit in Hydra vulgaris, representing a prototypic feature of neural evolution

2020 ◽  
Author(s):  
Yukihiko Noro ◽  
Hiroshi Shimizu ◽  
Katsuhiko Mineta ◽  
Takashi Gojobori
Keyword(s):  
Nervous System ◽  
Motor Neurons ◽  
Common Ancestor ◽  
Model Organism ◽  
The Body ◽  
Neural Function ◽  
Last Common Ancestor ◽  
Longitudinal Contraction ◽  
Living Fossil ◽  
Motor Circuits

AbstractThe last common ancestor of Bilateria and Cnidaria is believed to be one of the first animals to develop a nervous system over 500 million years ago. Many of the genes involved in the neural function of the advanced nervous system in Bilateria are well conserved in Cnidaria1. Thus, Cnidarian representative species, Hydra, is considered to be a living fossil and a good model organism for the study of the putative primitive nervous system in its last common ancestor. The diffuse nervous system of Hydra consists of several peptidergic neuron subsets. However, the specific functions of these subsets remain unclear. Using calcium imaging, here we show that the neuron subsets that express neuropeptide, Hym-1762,3 function as motor neurons to evoke longitudinal contraction. We found that all neurons in a subset defined by the Hym-176 gene (Hym-176A) or its paralogs (Hym-176B) expression4 are excited simultaneously, which is then followed by longitudinal contraction. This indicates not only that these neuron subsets are motor neurons but also that a single molecularly defined neuron subset forms a single coactive motor circuit. This is in contrast with the Bilaterian nervous system, where a single molecularly defined neuron subset harbors multiple coactive circuits, showing a mixture of neurons firing with different timings5. Furthermore, we found that the two motor circuits, one expressing Hym-176B in the body column and the other expressing Hym-176A in the foot, are coordinately regulated to exert region-specific contraction. Our results demonstrate that one neuron subset is likely to form a monofunctional circuit as a minimum functional unit to build a more complex behavior in Hydra. We propose that this simple feature (one subset, one circuit, one function) found in Hydra is a fundamental trait of the primitive nervous system.

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