scholarly journals Spatiotemporal organization of Ca2+ dynamics: A modeling‐based approach

HFSP Journal ◽  
2010 ◽  
Vol 4 (2) ◽  
pp. 43-51 ◽  
Author(s):  
Geneviève Dupont ◽  
Huguette Croisier
Keyword(s):  
Spatiotemporal Organization

scholarly journals Motor Patterns During Walking on a Slippery Walkway

2010 ◽  
Vol 103 (2) ◽  
pp. 746-760 ◽  
Author(s):  
Germana Cappellini ◽  
Yuri P. Ivanenko ◽  
Nadia Dominici ◽  
Richard E. Poppele ◽  
Francesco Lacquaniti
Keyword(s):  
Motor Output ◽  
Emg Activity ◽  
Head Orientation ◽  
Cycle Duration ◽  
Horizontal Shear ◽  
Motor Patterns ◽  
Spatiotemporal Organization ◽  
Surface Conditions ◽  
Gait Kinematics ◽  
Slippery Surface

Friction and gravity represent two basic physical constraints of terrestrial locomotion that affect both motor patterns and the biomechanics of bipedal gait. To provide insights into the spatiotemporal organization of the motor output in connection with ground contact forces, we studied adaptation of human gait to steady low-friction conditions. Subjects walked along a slippery walkway (7 m long; friction coefficient ≃ 0.06) or a normal, nonslippery floor at a natural speed. We recorded gait kinematics, ground reaction forces, and bilateral electromyographic (EMG) activity of 16 leg and trunk muscles and we mapped the recorded EMG patterns onto the spinal cord in approximate rostrocaudal locations of the motoneuron (MN) pools to characterize the spatiotemporal organization of the motor output. The results revealed several idiosyncratic features of walking on the slippery surface. The step length, cycle duration, and horizontal shear forces were significantly smaller, the head orientation tended to be stabilized in space, whereas arm movements, trunk rotations, and lateral trunk inclinations considerably increased and foot motion and gait kinematics resembled those of a nonplantigrade gait. Furthermore, walking on the slippery surface required stabilization of the hip and of the center-of-body mass in the frontal plane, which significantly improved with practice. Motor patterns were characterized by an enhanced (roughly twofold) level of MN activity, substantial decoupling of anatomical synergists, and the absence of systematic displacements of the center of MN activity in the lumbosacral enlargement. Overall, the results show that when subjects are confronted with unsteady surface conditions, like the slippery floor, they adopt a gait mode that tends to keep the COM centered over the supporting limbs and to increase limb stiffness. We suggest that this behavior may represent a distinct gait mode that is particularly suited to uncertain surface conditions in general.

scholarly journals A Septin Double Ring Controls the Spatiotemporal Organization of the ESCRT Machinery in Cytokinetic Abscission

2019 ◽  
Vol 29 (13) ◽  
pp. 2174-2182.e7 ◽  
Author(s):  
Eva P. Karasmanis ◽  
Daniel Hwang ◽  
Konstantinos Nakos ◽  
Jonathan R. Bowen ◽  
Dimitrios Angelis ◽  
...  
Keyword(s):  
Spatiotemporal Organization ◽  
Double Ring ◽  
Escrt Machinery

Does the cerebellum shape the spatiotemporal organization of muscle patterns? Insights from subjects with cerebellar ataxias

2020 ◽  
Vol 123 (5) ◽  
pp. 1691-1710 ◽  
Author(s):  
Denise J. Berger ◽  
Marcella Masciullo ◽  
Marco Molinari ◽  
Francesco Lacquaniti ◽  
Andrea d’Avella
Keyword(s):  
Muscle Activity ◽  
Activity Patterns ◽  
Specific Role ◽  
Modular Organization ◽  
Healthy Controls ◽  
Spatiotemporal Organization ◽  
Motor Commands ◽  
Cerebellar Damage ◽  
Cerebellar Ataxias ◽  
First Time

In recent studies, the decomposition of muscle activity patterns has revealed a modular organization of the motor commands. We show, for the first time, that muscle patterns of subjects with cerebellar damage share with healthy controls spatial, but not temporal and spatiotemporal, modules. Moreover, changes in spatiotemporal organization characterize the severity of the subject’s impairment. These results suggest that the cerebellum has a specific role in shaping the spatiotemporal organization of the muscle patterns.

scholarly journals Spatiotemporal organization of exocytosis emerges during neuronal shape change

2018 ◽  
Vol 217 (3) ◽  
pp. 1113-1128 ◽  
Author(s):  
Fabio L. Urbina ◽  
Shawn M. Gomez ◽  
Stephanie L. Gupton
Keyword(s):  
Cortical Neurons ◽  
Developmental Stages ◽  
Spatial Clustering ◽  
Shape Change ◽  
Cell Types ◽  
Melanoma Cells ◽  
Vesicle Fusion ◽  
Spatiotemporal Organization ◽  
Neuronal Morphogenesis ◽  
Developing Neurons

Neurite elongation and branching in developing neurons requires plasmalemma expansion, hypothesized to occur primarily via exocytosis. We posited that exocytosis in developing neurons and nonneuronal cells would exhibit distinct spatiotemporal organization. We exploited total internal reflection fluorescence microscopy to image vesicle-associated membrane protein (VAMP)–pHluorin—mediated exocytosis in mouse embryonic cortical neurons and interphase melanoma cells, and developed computer-vision software and statistical tools to uncover spatiotemporal aspects of exocytosis. Vesicle fusion behavior differed between vesicle types, cell types, developmental stages, and extracellular environments. Experiment-based mathematical calculations indicated that VAMP2-mediated vesicle fusion supplied excess material for the plasma membrane expansion that occurred early in neuronal morphogenesis, which was balanced by clathrin-mediated endocytosis. Spatial statistics uncovered distinct spatiotemporal regulation of exocytosis in the soma and neurites of developing neurons that was modulated by developmental stage, exposure to the guidance cue netrin-1, and the brain-enriched ubiquitin ligase tripartite motif 9. In melanoma cells, exocytosis occurred less frequently, with distinct spatial clustering patterns.

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